Note: Descriptions are shown in the official language in which they were submitted.
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AUTOMOTIVE COMPOSITE STRUCTURE PART WITH SPECIFICATED IMPACT
ENERGY ABSORPTION
BACKGROUND OF THE INVENTION
For many years the transportation industry has been concerned with designing
structural
members that do not add significantly to the weight of a vehicle. At the same
time, automotive
applications require structural members capable of providing reinforcement to
targeted portions
of the vehicle and permit ingress and egress to the passenger compartment in
the event of a
collision. While the devices found in the prior art may be advantageous in
some circumstances,
the prior art methods typically require the use of additional manufacturing
processes and steps
in either a supplier facility, a pre-production manufacturer stamping
facility, or the final vehicle
assembly planet which often increases labor demand, cycle time, capital
expense, and/or
required maintenance clean-up. Accordingly, there is needed a simple, low cost
structure or
system for reinforcing vehicle rails, such as a front rail or frame member,
which reinforces the
vehicle and controls deformation in any crash, enhances structural integrity,
and can be
efficiently incorporated into the vehicle manufacturing process. In addition,
there is also a need
for a relatively low cost system or structure which provides reinforcement and
inhibits distortion
to the frame or front rail structures in a vehicle, and which can serve to
manage energy in a
frontal/offset impact to the vehicle by reinforcing the frame member or front
rail to help target
applied loads and help redirect or tune energy management of deformation.
Furthermore there has been an increase in the need for selective reinforcement
of automotive
structures in order to control deformation and/or to meet various government
test standards. To
that end, structural foams and carriers have been developed for the purpose of
reinforcing
specific locations in vehicles. The primary focus of these reinforcements is
to add strength or
stiffness to a structure.
As will be appreciated by those skilled in the art, the three factors of
greatest general importance
in the evaluation of reinforcement effectiveness are stiffness, weight and
cost. With most prior
art techniques, increasing stiffness results in a corresponding penalty of
weight increase and/or
cost increase. For example, while using thicker gauges of metal increases
strength, it results in
an unwanted increase in weight. Similarly the use of exotic high-strength
alloys is effective to
increase strength, but this adds considerably to the cost of the vehicle.
Finally, it will be
recognised that the cost of resins is also a concern and thus structural foams
must be used
sparingly.
Another concern in the use of structural foams is the problem associated with
fully curing
material that is very thick. That is, in some prior art applications the
materials required to
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satisfactorily reinforce are so thick that it is difficult to achieve full
cure. Therefore, it will be
recognised that techniques for reinforcing hollow structures which do not
cause a substantial
weight and cost or curing problems have the potential to provide significant
advantages.
It is therefore an object of the present invention to provide a structural
reinforcement which
utilises structural foam in a manner which conserves resin.
It is a further object of the invention to provide such a reinforcement which
can be fully cured in
a short time.
It is still a further object to provide a low-cost, lightweight structural
reinforcement which provides
significant strength and stiffness to the reinforced region.
It is still a further object to provide localised structural reinforcement in
a manner that dissipates
impact energy causing any, at least, initial deformation, at a selected
location.
It is still a further object to provide a structural reinforcement which can
be transported easily to
the site of installation.
Yet a further object is to provide a structural member reinforced by a core
bonded to the
structural member by structural foam as previously described wherein channels
are provided
between the core and the structural member to allow the flow of moisture.
SUMMARY OF THE INVENTION
An object of the present invention is to redirect applied loads and manage
impact energy by
placing a reinforcement system in targeted areas of an automotive rail or
frame member. The
system generally employs at least one member or insert, which is attached or
adhered to the
chosen portion of the vehicle such as a frame or rail or any other portion of
an automotive
vehicle selected to inhibit deformation in the event of impact to the vehicle.
At least one of the
member or plurality of members are suitable for receiving an application of an
expandable
material coated over at least a portion of an exterior surface of the member.
The expandable
material disposed on the member is capable of activation and expansion when
exposed to heat
typically encountered in an automotive paint operation, such as e-coat and
other paint cycles in
a vehicle assembly plant. It is contemplated that the expandable material
disclosed in the
present invention, activates, expands, and adheres thereby structurally
reinforcing and
enhancing the strength and stiffness of the frame or front rail to redirect
applied loads and
energy. In one embodiment, the material is heat expandable and at least
partially fills a cavity
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defined by the rail, frame, or selected portion of the vehicle by structurally
adhering the rail and
the frame depending upon the size and shape of the cavity, during the e-coat
bake operation.
In another embodiment, the expandable material is a melt flowable material,
which upon the
application of heat will spread over a surface. The selected expandable
material may also
provide a variety of characteristics including structural reinforcement,
stress-strain reduction,
vibrational damping, noise reduction, or any combination thereof.
In a preferred embodiment the present invention therefore provides a
structural reinforcing
member to provide local reinforcement comprising a core to which is attached
one or more
pieces of structural foam the reinforcing member being provided with means for
attachment to
the member to be reinforced wherein the means for attachment is such that,
prior to foaming, a
channel is provided between the core, the structural foam and the internal
surface of the
member to be reinforced and that the foaming process enables the structural
foam to expand
and bond the core to the internal surface of the member to be reinforced.
In a preferred embodiment the structural foam is attached to the core as
several strips or spots.
In a further preferred embodiment the structural foam is provided in an amount
that a rigid bond
is formed between the core and the internal surface of the structure to be
reinforced and air
channels remain between the core and the internal surface for the flow of
moisture which may
be present due to condensation. We prefer that the structural foam cover from
20% to 45% of
the surface of the core.
The present invention further serves to manage crash energy typically
encountered during
frontal or rear impact testing of an automotive vehicle. More specifically,
the member or insert of
the present invention may be positioned such that it directs the energy of
impact and
furthermore in a preferred embodiment, may contain at least one and preferably
a plurality of
triggers consisting of notches, holes, or any other form of step change or
alteration to the
geometry of the member such as alterations to the geometry of an inner portion
or portions of
the member. The position of the reinforcing member within the automobile frame
may be such
that the reinforcement of one region deflects the energy on impact to another
second region
such that deformation takes place at the second region. Similarly where
internal triggers are
provided they can effectively target and direct axial bending to selected
portions of the system
and allow management of crash energy typically encountered during front offset
testing.
This is particularly useful in the reinforcement of vehicle rails which are
typically curved so that
greater reinforcement of one part of the curved structure can transfer energy
to a part of the
structure that is less reinforced so causing at least initial deformation at
the least reinforced
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PALL8Ai55NU0
area. This can be used to control rear or frontal deformation on impact
ensuring less
deformation at, for instance, door sills. The variation in degree of
reinforcement can be
accomplished by varying the strength and thickness of the reinforcing
material, such as the
gauge and type of materials, such as steel, used, providing foam reinforcement
around a core
member in some parts and not in others, or by the deliberate provision of
reinforcement in one
region coupled with non reinforcement at another region. This has been found
to be particularly
useful when reinforcing the S shaped section of the front ar rear rail of a
vehicle where greater
reinforcement in one, generally the lower bend of the S, can be used to ensure
that controlled
deformation takes place at the other bend of the S where there is less or in
some instances no
reinforcement.
The expandable material disposed over at least a portion of the member which
can be extruded,
molded, or "mini-application" bonded onto the member in either a pre-
production setting, such
as a stamping facility, or during the final assembly operation. The member,
and the selected
bonding or expandable material, is installed in the selected frame or rail
prior to the e-coat or
paint operation processing. Hence, the present invention provides flexibility
in the
manufacturing process since it can be utilized by either the frame or vehicle
component (front
rail) manufacturedsupplier or the final vehicle manufacturer with reduced
labor, capital expense,
maintenance requirements, and floor space demand. ante the expandable material
bonds and
cures to the selected rail or frame portion of the vehiGe, distortion of the
frame or rail, such as
front or rear rail, may be inhibited or managed during a frontaUoffset impact
event or any other
application of impact energy to the exterior of the vehicle. 8y absorbing
and/or transferring
certain impact energy and providing reinforcement to the frame or rail portion
of the vehicle, the
present invention provides a system for managing deformation to the vehide in
the event of a
frontal, offset or rear impact_
BRIEF DESCRIPTION OF THE DRAWINGS
The features and inventive aspects of the present invention will become more
apparent upon
reading the following detailed description, claims and drawings, of which the
following is a brief
description:
Figure 1 is an isometric view of a partially exploded automotive frame rail
showing the energy
management enhancement system in accordance with the teachings of the present
invention.
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_,...__ . , ~ . _
Figure 2 is an exposed view of a portion of the present invention depicted in
an automotive
space frame architecture or body-in-white design showing the position of the
at least one
member with the expandable material in the uncured state attached to a rail of
an automotive
vehicle.
Figure 3 is a portion of the system illustrated in Figure 1, showing an
alternative embodiment of
the at least one member of the present invention with the expandable material
in the uncured
state prior to attachment to the frame or rail of an automotive vehicle and
further showing an
attachment means of the present invention in the form of a clip assembly.
Figure 4 is a portion of the system described in Figure 1, showing an
alternative embodiment of
the at least one member of the present invention with the expandable material
in the uncured
state prior tc attachment to the frame or rail of an automotive vehicle.
Figure 5 is a portion of the system described in Figure 7, showing an
alternative embodiment of
the at least one member of the present invention with the expandable material
in the uncured
state prior to attachment to the frame or rail of an automotive vehiGe.
Figure 6 is a portion of the system described in Figure 1, showing an
alternative embodiment of
the at least one member of the present invention with the expandable material
in the uncured
state prior to attachment to the frame or rail of an automotive vehicle.
Figure 7 is an exploded perspective view, showing an aftemative embodiment of
the system
disposed within a closed form wherein the plurality of members are inter
locking and retained by
a third member also incorporating a self locking mechanism and a trigger of
the present
invention is depicted as a hole extending through the interior portion of the
member.
Figure 8 shows the reinforcing member of Figure 7.
Figure 9 is an exploded perspective view of the automotive rail reinforcement
system of the
present invention prior to the impact of energy typically encountered in
frontal impact testing of
an automotive vehicle.
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Figure 10 is an exploded perspective view of the automotive rail reinforcement
system of the
present invention after the impact of energy typically encountered in frontal
impact testing of an
automotive vehicle and the effect of axial bending to the system of the
present invention.
The invention is further illustrated by reference to the accompanying Figures
11 and 12 in which
Figure 11 shows a reinforcing member according to the present invention and
Figure 12 shows
the reinforcing member positioned inside the lower half of the front
longitudinal section of an
automobile.
Figure 13 is a schematic illustration of a vehicle front rail reinforced
according to one
embodiment of the present invention.
Figure 14 is a schematic illustration showing localised deformation of the
system illustrated in
Figure 13.
DETAILED DESCRIPTION OF THE INVENTION
The invention relates to methods and systems for managing energy and reducing
impact
deformation characteristics of automotive vehicles particularly to reduce
deformation in the
event of a frontal/offset impact event to the vehicle. More particularly, the
present invention
relates to a system for reinforcing, directing impact energy, and tuning the
management of said
impact energy to portions of an automotive vehicle, such as a frame or rail,
which effectuates
the reduction and inhibition of physical deformation or structural movement to
the occupant
compartment in the event of an impact to the exterior of the vehicle from
another object. The
system absorbs, dissipates and/or transfers the impact energy to reduce and
inhibit the resulting
deformation to the automotive vehicle. A reduction in impact deformation to
the vehicle may
serve to reduce occupant injury, allow continued passenger ingress and egress
to the vehicle
after an impact event, and reduce repair time and costs.
The automotive industry generally utilizes two primary modes for frontal
impact testing of
vehicles: full and offset. Full frontal impact testing is utilized for both
United States federal
compliance and assessment testing. While these tests are typically performed
at different
speeds (i.e. 30 mph for compliance and 35 mph for assessment), they both
relate to impact of a
barrier utilizing the full width of the front end structure of the tested
vehicle. The primary goal of
these tests is to assess occupant responses (femur loads, head injury
criteria, chest
deceleration, etc.) and validate the vehicle restraint systems (seatbelts,
airbags, etc.). The
offset impact test is performed at 40 mph with typically only 40% of the front
end of the tested
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vehicle impacting the barrier. One of the primary goals of the offset impact
test is to assess the
structural integrity of the vehicle structure itself.
Design for frontal crash energy management is a multidisciplinary process.
Crash energy
management is typically performed through a combination of the vehicle
structure and restraint
systems. Many automotive manufacturers seek vehicle structures that can be
designed to
absorb energy. Structural efficiency, defined as the ability to optimize
energy management as a
vehicle structure deforms upon impact, depends upon the configuration of the
design. For
purposes of frontal impact testing, the severe crush loads created by the
impact of energy
managing structures tend to decelerate the occupant compartment. The ability
of the energy
managing structures to transfer manageable loads to an occupant compartment,
coupled with
the ability of the restraint systems) to effectively dissipate such loads, may
help dictate how well
the occupant compartment responds to extreme loading, as well as how the
compartment
sustains minimal deformation and intrusion under certain conditions. For these
reasons, the
prior art focuses on at least two major considerations in the design of
vehicle structures for
crash energy management: (1 ) the absorption of kinetic energy of the vehicle,
and (2) the crash
resistance or strength needed to sustain the crush process inherent to the
testing process and
maintain passenger compartment integrity.
Traditional frontal energy management structures of automotive vehicles
generally consist of
three distinct crush zones. First, there will be a soft zone, typically the
bumper area or other
exterior fascia, followed by two stiffer zones. As defined and discussed
herein, the two stiffer
zones shall be referred to as primary and secondary. The primary crush zone is
traditionally
located immediately behind or adjacent to the soft crush zone, such as the
bumper system of a
vehicle, but in front of the powertrain compartment of a vehicle. The
secondary crush zone is
typically defined as the region bridging or tying the primary crush zone to
the occupant
compartment of the vehicle. For framed vehicles, such as trucks and larger
automobiles, the
secondary crush zone typically extends to the front body mount, as shown in
Figure 1 a. For
smaller vehicles, the frame can be integrated into the body-in-white design.
This type of design
is known in the art as space-frame architecture as shown in Figure 2. In the
case of space-
frame vehicle structures, the secondary crush zone extends rearward bridging
or tying the
primary crush zone to the vehicle firewall and toe-board areas of the occupant
compartment.
Due to the proximity of the secondary crush zone to the occupant compartment
of the vehicle,
design requirements and energy management control techniques need to be
utilized to minimize
potential intrusion into the occupant compartment.
Accordingly, a main goal of the crush zone technology known in the art, is to
manage the
maximum amount of energy without compromising the integrity of the occupant
compartment.
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In one embodiment, the present invention addresses these needs through an
energy
management system and structure which provides a stable platform or system for
the
progressive collapsing of the primary crush zone. Namely, as shown at Figures
8 and 9, the
present invention provides stability to the secondary crush zone which
inhibits buckling or
deformation while the primary crush zone is being crushed so that the overall
structure is
progressively collapsed in a predetermined and managed manner. As depicted in
Figures 8 and
9, the present invention may comprise a plurality of triggers to effectuate
axial collapse by
creating opposing or dual bending modes. As illustrated in Figures 10 to 13,
the invention may
create local collapsing by reinforcing the lower part of the front rail but
not the upper part. The
system or structure of the present invention further serves to manage crash
energy by
attempting to control the deformation characteristics of either or both of the
primary and
secondary crush zones in such a way to minimize occupant compartment
intrusion.
As is well known in the art, energy management structures deform (collapse) in
a combination of
axial and bending modes. Many existing energy management systems utilize the
bending mode
which results in lower energy management capabilities. For instance, since the
bending mode
is less efficient from an energy management standpoint, it typically requires
much heavier
designs or reinforcement configurations to manage the same amount and type of
energy as an
axially collapsing design. In most,designs where weight is a criteria in
vehicle design and
performance, the axial mode is the preferred method of energy management. The
bending
mode, which involves the formation of localized hinge mechanisms and linkage
type kinematics,
is also a lower energy mode. For example, a structure will have a tendency to
collapse in a
bending mode due to the lower energy mode. Based upon this, even a structure
specifically
designed for axial collapse will default to the bending mode unless other
structural features are
provided in the design to enhance stability and resistance to off-angle
loading.
Axial folding is also considered to be the most effective mechanism of energy
absorption. It is
also the most difficult to achieve due to potential instability and the lower
energy default to the
bending mode. Accordingly, in a preferred embodiment the energy management
system or
structure of the present invention seeks to maximize axial collapse of
portions of an automotive
vehicle, while minimizing bending, through the use of at least one, and
preferably a plurality of
triggers designed within either or both of the primary and secondary crush
zones. The trigger or
triggers of the present invention are defined as a change or discontinuity in
the part geometry of
either or both of the primary and secondary crush zones forming the structure
of the present
invention designed to create stress risers to cause localized bending. A
plurality of triggers, or
combinations of different geometrically designed triggers, are preferably
utilized in the present
invention to initiate folds in the structure inducing axial collapse in
targeted portions of at least
one of the three distinct crush zones of the frontal energy management
structure shown in
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Figures 1 and 2. When the triggers of the present invention are used they are
sized and
designed to ensure that axial collapse of the structure shown at Figures 1 and
2 can occur at
sufficiently high loads in order to maximize the amount of energy managed by
the structure or
the amount of energy typically encountered in frontal impact testing.
Triggers currently found in the prior art have generally been modifications to
the exterior portions
of metal structural reinforcement members or inserts used to reinforce a
chosen body portion or
cavity of an automotive vehicle, such as a rail, pillar, cross-member, etc.,
as well as any other
area immediately adjacent to the occupant compartment of an automotive
vehicle. These prior
art triggers typically consist of holes or part contours to the exterior
portion of the structural
reinforcement member or insert. However, in a preferred embodiment, through
modifications to
the internal portion of a structural reinforcement member or insert, the
present invention
provides at least one, and preferably a plurality of internal triggers for use
in managing energy
typically encountered by an automotive vehicle during frontal impact testing.
When used, the
internal triggers of the present invention effectively target and direct axial
bending to selected
portions of the structure and can comprise notches, holes, or any other form
of step change or
alteration to the geometry of an inner portion or portions of the structural
reinforcement member
or insert. For example, the structural reinforcement member or insert of the
present invention,
serves a plurality of purposes and provides a method for managing impact
energy. First, the
member or insert acts as a stabilizer which reinforces the secondary crush
zone thereby
allowing the primary crush zone to maximize axial crush. Once the primary
crush zone has
achieved maximum ability to absorb impact energy, the secondary crush zone of
the structure of
the present invention must be designed to absorb some additional energy as a
means to reduce
deformation to the occupant compartment of the vehicle. The structure of the
present invention,
utilizing a plurality of triggers such as notches or a cut-away section of the
member or insert,
serves to initiate bending of the structure based upon its existing geometry.
In one embodiment of the present invention, at least one member 12 or insert
is placed within,
attached, affixed, or adhered to at least a portion of a frame or rail of an
automotive vehicle
wherein at least one member 12 includes an expandable or foamable material 14
supported by,
and disposed along portions of the member 12. The member 12 has an interior
and an exterior
portion and may be configured in any shape, design, or thickness corresponding
to the
dimensions of the selected frame or rail of the vehicle and may further
comprise a plurality of
triggers integrated within an interior portion of the member 12, which are
designed and
incorporated to specifically tune or target impact energy for either
absorption or redirection to
other portions of the vehicle. The expandable material 14 extends along at
least a portion of the
length of the exterior portion of the member 12, and may fill at least a
portion of a cavity or
space defined within the frame or rail.
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The system 10 generally employs at least one member 12 adapted for stiffening
the structure to
be reinforced, such as a frame or front or rear rail found in automotive
vehicles, and helping to
better manage impact energy typically encountered in a frontaUoffset impact to
the vehicle. In
use, the member or members are disposed within or mechanically attached, snap-
fit, affixed, or
adhered by adhesive onto at least a portion of the chosen frame or front or
rear rail with the heat
activated expandable material serving as a load transferring, energy absorbing
medium
disposed along at least one exterior surface of the member. In one embodiment,
the member or
members 12 are comprised of an injection molded polymeric carrier, an
injection molded
polymer, graphite, carbon, or a molded metal such as aluminum, magnesium, or
titanium as well
as an alloy derived from the materials or a foam derived from the materials or
other metallic
foam and is at least partially coated with an expandable material 14 on at
least one of its sides,
and in some instances on four or more sides.
In addition, it is contemplated that the member could comprise a nylon or
other polymeric
material as set forth in commonly owned U.S. Patent No. 6,103,341, expressly
incorporated by
reference herein, as well as injection molded, extruded, die cast, or machined
member
comprising materials such as nylon, PBI, or PEI. The member or members may
also be
selected from materials consisting of extruded aluminum, aluminum foam,
magnesium,
magnesium alloys, molded magnesium alloys, titanium, titanium alloys, molded
titanium alloys,
polyurethanes, polyurethane composites, low density solid fillers, and formed
SMC and BMC.
Still further, the member adapted for stiffening the structure to be
reinforced could comprise a
stamped and formed cold-rolled steel, a stamped and formed high strength low
alloy steel, a roll
formed cold rolled steel, or a roll formed high strength low alloy steel.
A number of structural reinforcing foams are known in the art and may also be
used to produce
the expandable material of the present invention. A typical structural foam
includes a polymeric
base material, such as an epoxy resin or ethylene-based polymer which, when
compounded
with appropriate ingredients (typically a blowing agent, a curing agent, and
perhaps a filler),
typically expands and cures in a reliable and predictable manner upon the
application of heat or
another activation stimulus. The resulting material has a low density and
sufficient stiffness to
impart desired rigidity to a supported article. From a chemical standpoint for
a thermally
activated material, the structural foam is usually initially processed as a
thermoplastic material
before curing. After curing, the structural foam typically becomes a thermoset
material that is
fixed and incapable of flowing.
The expandable material is generally a thermoset material, and preferably a
heat-activated
epoxy-based resin having foamable characteristics upon activation through the
use of heat
CA 02467259 2004-05-14
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typically encountered in an e-coat or other automotive paint oven operation.
As the expandable
material is heated, it expands, cross-links, and structurally bonds to
adjacent surfaces. An
example of a preferred formulation is an epoxy-based material that may include
polymer
modificis such as an ethylene copolymer or terpolymer that is commercially
available from L&L
Products, Inc. of Romeo, Michigan, under the designations L-5204, L-5206, L-
5207, L-5208, L-
5209, L-5214, and L-5222. One advantage of the preferred structural foam
materials over prior
art materials is the preferred materials can be processed in several ways.
Possible processing
techniques for the preferred materials include injection molding, blow
molding, thermoforming,
direct deposition of pelletized materials, extrusion or extrusion with a mini-
applicator extruder.
This enables the creation of part designs that exceed the design flexibility
capability of most
prior art materials. In essence, any foamable material that imparts structural
reinforcement
characteristics may be used in conjunction with the present invention. The
choice of the
expandable material used will be dictated by performance requirements and
economics of the
specific application and requirements. Generally speaking, these automotive
vehicle
applications may utilize technology and processes such as those disclosed in
U.S. Patent Nos.
4,922,596, 4,978,562, 5,124,186, and 5,884,960 and commonly owned, co-pending
U.S.
Application Serial Nos. 09/923,138, and PCT Application Nos. and W002/14109
filed 08 August
2001, W001/58741 filed 18 January 2001, W001/68394 filed 01 March 2001,
W002/26550 filed
26 September 2001, W002/26551 filed 26 September 2001, W002/26549 filed 26
September
2001, and particularly, W001141950 filed 07 December 2000, all of which are
expressly
incorporated by reference.
The structural foam may be applied to the surface of the core in any suitable
manner and the
preferred manner will depend upon the nature of the core material. For example
if the core is of
a plastic such as glass reinforced polyamide and produced by injection
moulding then the
structural foam may be applied by two shot injection moulding or over
moulding.
Alternatively if the core is of metal produced, for example, by stamping, the
structural foam may
be applied by melt bonding or through use of an adhesive. In a further
alternative irrespective of
the nature of the core the structural foam may be mechanically attached to the
core. Examples
of means of mechanical attachment include pins or grooves as described in
United States
Patent 6,311,452. A preferred means of attachment is pushpins which may be
pushed through
holes formed in the core to receive the pins. In this preferred embodiment the
need for special
moulding and/or adhesion of the structural foam is avoided.
The invention provides a way to reduce cost, improve stiffness, and increase
the possibility of
achieving full cure of the structural foam all through the use of a composite
construction. The
surface of the reinforcement member may be keyed to permit uncured resin to be
applied such
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that mechanical interlocking between the member and the applied uncured resin
occurs. This
interlocking permits the resin to be positioned on the reinforcement member
without the
necessity of heating the reinforcement member, using a secondary adhesive,
heating the
uncured structural foam, or using a pressure sensitive uncured structural
foam. Similar benefits
may be achieved if the structural foam is attached to the core with push pins.
In addition to
processing ease, the keyed surface push pins produce a structure that is
strongly resistant to
damage during shipping or handling in an assembly plant. In one aspect the
primary uncured
heat expandable material attached to the reinforcing member is not pressure
sensitive. This
enables packaging such that adjacent performed parts do not adhere to each
other during
shipping (i.e., the material does not behave as a pressure sensitive
adhesive).
The construction of the present invention enables a number of different
options for the preferred
use of the invention the installation in a hollow structural part of a motor
vehicle. One possibility
is to attach end caps (not shown) to the reinforcing structure. These end caps
may have an
integral fastener or be spring loaded to enable installation and positioning
in a vehicle. Another
option is to form a part that has the near net shape of the structure that it
is intended to reinforce
such that when installed into a hollow cavity it becomes trapped and is
thereby positioned. This
would typically be a vehicle area that requires a reinforcement that is not
linear and involves
laying a part into a partial cavity that is later capped with another piece of
sheet metal. An
additional method of installation is to apply a pressure sensitive adhesive to
some surface of the
composite reinforcing structure. Depending on goats of the reinforcement, the
pressure
sensitive adhesive may or may not also have structural characteristics
following cure.
In a preferred embodiment the structural reinforcing member of this invention
is used to
reinforce the front longitudinal section of an automobile sub frame. The front
longitudinal section
of an automobile form is the structural member which helps support the engine
and which also
carries fuel pipes to the engine. The front longitudinal section of an
automobile is typically a
bending box shaped tube and the reinforcement member is one that fits into the
box shaped
tube and reduces deformation of the section through bending upon end impact
onto the section
during a frontal crash of the vehicle. In this embodiment the reinforcing
member preferably
extends at least some way through the length of the longitudinal member most
likely to undergo
deformation upon frontal crash. In this instance the reinforcing member is
preferably U or D
shaped with strips of structural foam along the majority of the length of part
of the walls of the
member. Alternatively the structural foam may be spotted onto the reinforcing
core.
Typically the front rail contains at least two bends, sometimes forming an S
shape. It is often
desired that the initial deformation of the front rail on impact occurs at the
bend of the rail
nearest the front of the vehicle. This can be accomplished by having a
different degree of
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reinforcement in the two bends with a greater degree of reinforcement at the
bend further from
the front of the vehicle. This may be accomplished by the use of a single
reinforcement member
with different reinforcing ability at the two bends, this may be accomplished
through the use of
materials of different strengths and stiffnesses, the provision of less
reinforcing foam or the
absence of any reinforcement a the bend nearest the front of the vehicle.
Alternatively it may be
accomplished by reinforcing the first bend and not the second bend.
The resin whether it be as strips or spots are normally expandable. That is,
upon the application
of heat they will expand, typically by a foaming reaction, and preferably to
at least 150% the
volume of the unexpanded state, but more preferably twice. In a preferred
embodiment, the
resin used to form the resin strips or spots is an epoxy-based material.
Resin preferably forms about 5% to about 75% by weight and more preferably
from about 15%
to 65% by weight of the composition. Filler preferably forms from about 0% to
about 70% by
weight and more preferably from about 20% to about 50% by weight of the
composition.
Blowing agent preferably forms from about 0% to about 10% by weight and more
preferably
from about 0.2% to 5% by weight of the composition. Curing agent preferably
forms from about
0% to about 10% by weight and more preferably from about 0.5% to 5% by weight
of the
composition. Accelerator preferably forms from about 0% to about 10% by weight
and more
preferably from about 0.3% to 5% by weight of the composition. One preferred
formulation is
set forth in Table 1 below.
Ingredient % by weight
Epoxy Resin 15% to 65%
Ethylene Copolymer 0% to 20%
Blowing Agent 0.2% to 5%
Curing Agent 0.5% to 5%
Accelerator 0.3% to 5%
Filler 20% to 50%
As stated, the heat expandable material is most preferably a heat-activated,
substantially epoxy-
based material. However, other suitable materials may also be used. These
include polyolefin
materials, copolymers, and terpolymers with at least one monomer type an alpha-
olefin,
phenol/formaldehyde materials, phenoxy materials, polyurethane materials with
a high glass
transition and others. In general the desired characteristics of this heat
expandable material will
be high stiffness, high strength, high glass transition temperature, good
corrosion resistance,
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ability to adhere to contaminated metallic and polymer surfaces, fast cure
upon activation, good
handling characteristics, low cure density, low cost, and long shelf life.
The core of the reinforcing member may be of any suitable material that has
the strength/weight
balance to provide the desired degree of reinforcement at minimum weight. The
core may be of
plastic material in which case it may be produced by injection moulding or
extrusion. Where
plastic is used glass filled polyamide (nylon) is a preferred material.
Alternatively the core may
be of a metal where steel or aluminium, are preferred. Where the core is of
metal is may be
formed by extrusion, die casting of stamping, extrusion and stamping being
preferred.
In the preferred embodiment where the invention is used to provide structural
reinforcement in
automobiles the foamable material is such that it is activated to foam at a
temperature above the
temperatures employed in the anti-corrosion coating process (known as a coat).
The foamable
material is preferably activated at the temperature employed to bake the
coating material which
is typically 149°C or higher although there is a trend towards the use
of lower temperatures.
The core material, on the other hand, should be such that it is largely
unaffected by the
conditions, particularly temperature, to which the automobile is subjected
during manufacture.
In a preferred embodiment the invention is used to reinforce the format
longitudinal section of an
automobile. In this embodiment the reinforcing member should be such that
pipes and wires
and particularly fuel pipes can be pushed through the longitudinal section
including the
reinforcing member, prior to foaming. Accordingly it is preferred that the
reinforcing member be
channel shaped and be free from internal protuberances, such as ribs, which
could inhibit the
passage of such wires and pipes.
Additional foamable or expandable materials that could be utilized in the
present invention
include other materials which are suitable as bonding, energy absorbing, or
acoustic media and
which may be heat activated foams which generally activate and expand to fill
a desired cavity
or occupy a desired space or function when exposed to temperatures typically
encountered in
automotive e-coat curing ovens and other paint operation ovens. Though other
heat-activated
materials are possible, a preferred heat activated material is an expandable
or flowable
polymeric formulation, and preferably one that can activate to foam, flow,
adhere, or otherwise
change states when exposed to the heating operation of a typical automotive
assembly painting
operation. For example, without limitation, in one embodiment, the polymeric
foamable material
may comprise an ethylene copolymer or terpolymer that may possess an alpha-
olefin. As a
copolymer or terpolymer, the polymer is composed of two or three different
monomers, i.e.,
small molecules with high chemical reactivity that are capable of linking up
with similar
molecules. Examples of particularly preferred polymers include ethylene vinyl
acetate, EPDM,
or a mixture thereof. Without limitation, other examples of preferred foamable
formulations
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commercially available include polymer-based materials available from L&L
Products, Inc. of
Romeo, Michigan, under the designations as L-2018, L-2105, L-2100, L-7005, L-
7101, L-7102,
L-2411, L-2420, L-4141, etc. and may comprise either open or closed cell
polymeric base
material.
Further, it is contemplated that the expandable material of the present
invention may comprise
acoustical damping properties which, when activated through the application of
heat, can also
assist in the reduction of vibration and noise in the overall automotive
frame, rail, and/or body of
the vehicle. In this regard, the now reinforced and vibrationally damped frame
or front rail will
have increased stiffness which will reduce natural frequencies, that resonate
through the
automotive chassis thereby reducing transmission, blocking or absorbing noise
through the use
of the conjunctive acoustic product. By increasing the stiffness and rigidity
of the frame or front
rail, the amplitude and frequency of the overall noise/vibration that occurs
from the operation of
the vehicle and is transmitted through the vehicle can be reduced.
Still further, it will be appreciated that the carrier of the reinforcing
member used in the present
invention, as well as the material forming the geometric step-changes or
triggers found in the
carrier or member of the present invention, may comprise a reactive or non-
reactive material,
which yields high compressive strength and moduli and may either form the
carrier or member
itself or be capable of filling or coating the carrier or member. Generally
speaking, a desired
material, which exhibits such higher compressive strength and moduli may be
selected from the
group consisting of a syntactic foam, syntactic-type foam, or low density
fillers, such as spheres,
hollow spheres, ceramic spheres, including pelletized and extruded
formulations thereof. In
addition, the carrier or member may comprise a concrete foam, syntactic foam,
aluminum foam,
aluminum foam pellets, or other metallic foam, as well as alloys thereof. An
example of such
materials include commonly assigned U.S. Provisional Patent Application Serial
No. 60/398,411
for "Composite Metal Foam Damping/Reinforcement Structure" filed July 25, 2002
and hereby
incorporated by reference. Other materials suitable for use as the carrier or
member in the
present invention include polysulfone, aluminum and other metal foams,
concrete, polyurethane,
epoxy, nylon, phenolic resin, thermoplastic, PET, SMC, carbon fillers
including materials sold
under the trade name ICEVLAR. In addition, it is also contemplated that the
carrier or member of
the present invention, or portions of the carrier or member of the present
invention, may utilize
or comprise a material sold under the trade name ISOTRUSS, as described and
set forth in U.S.
Patent No. 5,921,048 for a Three-Dimensional Iso-Truss Structure issued July
13, 1999,
WO/0210535 for Iso-Truss Structure published by the World Intellectual
Property Organization
on February 7, 2002, and a pending U.S. provisional patent application before
the U.S. Patent &
Trademark Office entitled: Method And Apparatus For Fabricating Complex,
Composite
CA 02467259 2004-05-14
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Structures From Continuous Fibers, all of which have been commonly-assigned to
Brigham
Young University and are hereby incorporated by reference herein.
It is further contemplated that any number of the suitable materials disclosed
and set forth
herein for use as the carrier or member of the present invention may be
formed, delivered, or
placed into a targeted or selected portion of a transportation vehicle (i.e.
land, rail, marine, or
aerospace vehicle) through a variety of delivery mechanisms and systems that
are known in the
art. For example, the material may be poured, pumped, extruded, casted, or
molded into any
number of desired shapes or geometry depending upon the selected application
or area to be
reinforced. Further, the material may be reactive, non-reactive, expandable,
or non-expandable
and may be further utilized, incorporated, or filled into a hollow core,
shell, or blow-molded
carrier for later placement within a selected portion of the vehicle during
any phase of the pre-
manufacturing or manufacturing process.
Although the use of such impact absorbing materials and members are directed
to an
automotive frame, it is contemplated that the present invention can be
utilized in other areas of
an automotive vehicles that are used to ensure ingress and egress capability
to the vehicle by
both passengers as well as cargo, such as closures, fenders, roof systems, and
body-in-white
(BIW) applications which are well known in the art.
In addition to the use of an acoustically damping material along the member,
the present
invention could comprise the use of a combination of an acoustically damping
material and a
structurally reinforcing expandable material along different portions or zones
of the member
depending upon the requirements of the desired application. Use of acoustic
expandable
materials in conjunction with structural material may provide additional
structural improvement
but primarily would be incorporated to improve NVH characteristics.
While several materials for fabricating the impact absorbing or expandable
material have been
disclosed, the material can be formed of other materials provided that the
material selected is
heat-activated or otherwise activated by an ambient condition (e.g. conductive
materials,
welding applications, moisture, pressure, time or the like) and expands in a
predictable and
reliable manner under appropriate conditions for the selected application. One
such material is
the epoxy based resin disclosed in U.S. Patent Application Serial No.
09/268,810, the teachings
of which are incorporated herein by reference, filed with the United States
Patent and
Trademark Office on March 8, 1999 by the assignee of this application. Some
other possible
materials include, but are not limited to, polyolefin materials, copolymers
and terpolymers with at
least one monomer type an alpha-olefin, phenol/formaldehyde materials, phenoxy
materials,
polyurethane materials with high glass transition temperatures, and mixtures
or composites that
16
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may include even metallic foams such as an aluminum foam composition. See
also, U.S.
Patent Nos. 5,766,719; 5,755,486; 5,575,526; 5,932,680 (incorporated herein by
reference). In
general, the desired characteristics of the expandable material include high
stiffness, high
strength, high glass transition temperature (typically greater than 70 degrees
Celsius), and good
adhesion retention, particularly in the presence of corrosive or high humidity
environments.
In applications where a heat activated, thermally expanding material is
employed, an important
consideration involved with the selection and formulation of the material
comprising the
structural foam is the temperature at which a material reaction or expansion,
and possibly
curing, will take place. In most applications, it is undesirable for the
material to activate at room
temperature or the ambient temperature in a production line environment. More
typically, the
structural foam becomes reactive at higher processing temperatures, such as
those
encountered in an automobile assembly plant, when the foam is processed along
with the
automobile components at elevated temperatures. While temperatures encountered
in an
automobile assembly body shop ovens may be in the range of 148.89 °C to
204.44 °C (300 °F
to 400 °F), and paint shop oven temps are commonly about 93.33
°C (215 °F) or higher. If
needed, various blowing agents activators can be incorporated into the
composition to cause
expansion at different temperatures outside the above ranges.
Generally, prior art expandable acoustic foams have a range of expansion
ranging from
approximately 100 to over 1000 percent. The level of expansion of the material
may be
increased to as high as 1500 percent or more, but is typically between 0% and
300%. In
general, higher expansion will produce materials with lower strength and
stiffness properties.
It is also contemplated that the foamable or expandable material could be
delivered and placed
into contact with the member through a variety of delivery systems which
include, but are not
limited to, a mechanical snap fit assembly, extrusion techniques commonly
known in the art as
well as a mini-applicator technique as in accordance with the teachings of
commonly owned
U.S. Patent No. 5,358,397 ("Apparatus For Extruding Flowable Materials"),
hereby expressly
incorporated by reference. In another embodiment, the expandable material is
provided in an
encapsulated or partially encapsulated form, which may comprise a pellet,
which includes an
expandable foamable material, encapsulated or partially encapsulated in an
adhesive shell,
which could then be attached to the member in a desired configuration. An
example of one
such system is disclosed in commonly owned, co-pending U.S. Application Serial
No.
09/524,298 ("Expandable Pre-Formed Plug"), hereby incorporated by reference.
In addition,
preformed patterns may also be employed such as those made by extruding a
sheet (having a
flat or contoured surface) and then die cut in accordance with a predetermined
configuration.
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As stated, the reinforcement parts of the present invention are particularly
useful for the purpose
of structural reinforcement of a hollow vehicle cavity. When the vehicle is
heated, the heat
expandable material (structural foam) expands to contact the surface of the
hollow cavity that it
is intended to reinforce. It is not necessary that the space between the
member and the inner
surface of the hollow cavity or other surface being reinforced be fully filled
with expanded heat
expandable material for substantial reinforcement to occur. It is often
preferred that the hollow
cavity not be fully filled to allow channels for the flow of moisture derived
from condensation.
A particular additional benefit of the present invention is that it permits
large sections to be
reinforced with full confidence that the structural foam material will fully
cure. Because the
material must be heated to cure, it is important that full cure occur to
obtain optimum properties.
If very large sections are filled with structural foam alone, then the
difficulty of obtaining sufficient
heat transfer through the material can be difficult. Use of a composite
reinforcing member
greatly increases the probability that full cure will occur. This is possible
both because it permits
the possibility of using less heat activated foam and the rigid reinforcement
provides a heat
transfer conduit to the inner surface of the heat-activated material. An
additional benefit is that a
reinforcement with less weight and lower cost can be provided for certain
design types. A
further additional benefit is that it permits the possibility of producing a
part that is highly
resistant to damage during transport owing to the support that the keyed
reinforcing member
provides to the heat expandable material.
Composite reinforcing structure may be constructed by dispensing heat
activated expandable
material onto the reinforcing member using an extruder, including an extruder
that is articulated
by a robot. This process relies on the extruder being positioned such that
molten heat
expandable material is dispensed into the reinforcement member. Upon cooling,
the heat
expandable material will stiffen and resist deformation while being
transported. Upon sufficient
reheating (a temperature necessarily higher than the temperature used to shape
the heat
expandable material), the heat expandable material will be activated such that
it will expand and
cure in the hollow vehicle cavity and thereby provide the desired
reinforcement. A particularly
preferred way of dispensing material onto a reinforcing member is to use a
robot articulated
extruder to press the molten heat expandable material into the sections. An
additional method
is to insert injection mould this material onto the reinforcing structure.
Another way of
constructing this kind of reinforcement is to separately extrude the heat
expandable material into
a shape that mimics the section of a keyed location and then slide or snap the
heat expandable
material into the keyed section of a keyed reinforcing member. A further
additional way of
making the composite construction is to press molten of deformable heat
expandable material
into the keyed section of the reinforcing member.
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Alternatively the foamable material may be fastened to the reinforcing member
by, for example,
pins.
The present invention is graphically represented in Figure 1 and includes of
an automotive
frame or rail energy management enhancement system 10 formed in accordance
with the
teachings of the present invention. The system 10 imparts an increased
capability redirect
applied loads and impact energies to a preferred portion of an automotive
vehicle and, thus,
may be used in a variety of applications and areas of an automotive or other
moving vehicle.
For instance, the energy management enhancement system 10 may be used to
inhibit
deformation and distortion to targeted portions of an automotive vehicle,
including the frame,
rail, door, or other structural members used in vehicles, in the event of an
impact to the exterior
of the vehicle by an outside body. The system 10 serves to target, tune, or
manage energy for
absorption and/or transfer to other portions of the vehicle. As shown in
Figures 1 and 2, the
present invention comprises at least one member 12 having an interior portion
and an exterior
portion composed of an injection molded carrier provided with a suitable
amount of an
expandable material 14 molded on its sides which can be placed, geometrically
constrained,
attached, or adhered to at least a portion of an automotive structural rail or
frame 16 through an
attachment means 18 (not shown) used to place the member 12 within the rail or
frame 16. The
attachment means 18 may consist of a self-interlocking assembly,
gravity/geometrically
constrained placement, adhesive, a molded in metal fastener assembly such as a
clip, push pins
or snaps, integrated molded fasteners such as a clip, push pins, or snaps as
well as a snap-fit
assembly which is well known in the art. As shown in Figures 3 and 4, the
attachment means
18 may consist of a clip. The automotive frame or rail 16 imparts structural
integrity to the
vehicle and may serve as the carrier of certain body panels of the automotive
vehicle which may
be viewable, and capable of receiving impact energy, from the exterior of the
vehicle. By
attaching the member 12 having the expandable material 14 to the frame or rail
16, additional
structural reinforcement is imparted to the targeted portion of the frame or
rail 16 where the
member 12 is attached.
The present invention serves to place this targeted reinforcement in selected
areas of a frame or
rail 16 and provides the capability to absorb, direct, or manage impact energy
typically
encountered during an impact event from an external source or body, such as
that typically
encountered during a frontal/offset impact or collision. It is contemplated
that the member 12
and the expandable material 14, after expansion, create a composite structure
whereby the
overall system 10 strength and stiffness are greater than the sum of the
individual components.
In the event of an impact to the exterior of the vehicle, the impact energy is
managed by either
energy absorption/dissipation or targeted direction of the energy to specific
areas of the vehicle.
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The energy management features of the present invention may also utilize
targeted placement
of a plurality of triggers 20 incorporated within the interior portion of the
member 12 or outside of
the member 12 along the frame or rail 16, as shown in Figure 1. The triggers
20 are targeted or
otherwise tuned for placement along either or both of selected areas of the
frame or rail 16
S andlor the plurality of members 12 to direct the placement of energy to
targeted areas of the
vehicle during an impact and initiate folds in the structure inducing axial
collapse. As shown in
Figures 2-6, the system 10 of the present invention can be integrated within
vehicle cavities
utilizing a plurality of members 12 in a variety of predetermined shapes,
forms, and thicknesses
corresponding to the size, shape, and form of the cavity of the specific
automotive application
selected for energy management without compromising the visual appearance,
functionality, or
aesthetic quality of the exterior portions and paintable surfaces of the
vehicle. The trigger or
plurality of triggers 20 are incorporated and integrated within an interior
portion of the member
12 and designed as notches, holes, or any other step change in the geometry of
the interior
portion of the member. In some cases the triggers 20 may simply consist of a
segment of the
interior portion of the member that is specifically not coated with an
expandable material as
shown in Figure 2. In other applications, a plurality of triggers 20 may be
utilized such as a
notch as shown in Figure 1 or a cut-out hole of a portion of the member 12, as
also shown in
Figure 1. As graphically shown in Figures 3 and 4, a trigger 20 of the present
invention may
also comprise a hole or other step change in the geometry of member 12
comprising a varying
wall thickness of the trigger 20.
The expandable material 14 includes an impact energy absorbing, structural
reinforcing
material, which results in either a rigid or semi-rigid attachment to at least
one member 12
having at least one trigger 20. It is contemplated that the material 14 could
be applied to at least
one member 12 in a variety of patterns, shapes, and thicknesses to accommodate
the particular
size, shape, and dimensions of the cavity to be filled by the expandable
material after activation.
The placement of the member 12 along the selected frame or rail 16 as well as
placement of the
material 14 along the surfaces of the member 12 itself, and particularly
either or both of the
interior portion and exterior portion of the member 12, can be applied in a
variety of patterns and
thicknesses to target or tune energy management enhancement or deformation
reduction in
selected areas of the vehicle where a reduction or redirection of impact
energy would serve to
limit damage to the vehicle passenger compartment and permit ingress and
egress to the
vehicle for passengers. The material 14 is activated to accomplish expansion
through the
application of heat typically encountered in an automotive e-coat oven or
other heating operation
in the space defined between the member 12, now attached to the frame or rail
16 in either or
pre-production facility or the final vehicle assembly operation. The resulting
composite structure
includes a wall structure formed by the rail or frame 16 joined to the at
least one member 12 with
the aid of the material 14. It has been found that structural attachment
through the use of the
CA 02467259 2004-05-14
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member 12 and the material 14 is best achieved when the material 14 is
selected from materials
such as those offered under product designations L-5204, L-5205, L-5206, L-
5207, L-5208, L-
5209, L-5214, and L-5222 sold by L&L Products, Inc. of Romeo, Michigan. For
semi-structural
attachment of the frame or rail 16 through the use of the member 12 and the
material 14, best
results were achieved when the material 14 is selected from materials such as
those offered
under product designations L-4100, L-4200, L-4000, L-2100, L-1066, L-2106, and
L-2108 sold
by L&L Products, Inc. of Romeo, Michigan. '
The properties of the expandable material include structural foam
characteristics, which are
preferably heat-activated to expand and cure upon heating, typically
accomplished by gas
release foaming coupled with a cross-linking chemical reaction. The material
14 is generally
applied to the member 12 in a solid or semi-solid state. The material 14 may
be applied to the
outer surface of the member 12 in a fluid state using commonly known
manufacturing
techniques, wherein the material 14 is heated to a temperature that permits
the foamable
material to flow slightly to aid in substrate wetting. Upon curing the
material 14 hardens and
adheres to the outer surface of the member 12. Alternatively, the material 14
may be applied to
the member 12 as precast pellets, which are heated slightly to permit the
pellets to bond to the
outer surface of the member 12. At this stage, the material 14 is heated just
enough to flow
slightly, but not enough to cause the material 14 to thermally expand.
Additionally, the material
14 may also be applied by heat bonding/thermoforming or by co-extrusion. Note
that other
stimuli activated materials capable of bonding can be used, such as, without
limitation, an
encapsulated mixture of materials that, when activated by temperature,
pressure, chemically, or
other by other ambient conditions, will become chemically active. To this end,
one aspect of the
present invention is to facilitate a streamlined manufacturing process whereby
the material 14
can be placed along the member 12 in a desired configuration wherein the
member 12 is then
attached by the attachment means 18 or geometrically constrained to the frame
or rail 16
without attachment means at a point before final assembly of the vehicle. As
shown in Figures 3
and 4, the attachment means 18 of the present invention may comprise a clip
which is well
known in the art. In this regard, the system 10 of the present invention
provides at least one, but
possibly a plurality of, members 12 which are placed along and attached to the
selected frame
or rail 16 such that adequate clearance remains for existing and necessary
hardware that may
be located inside a traditional automotive body cavity to provide window
movement, door trim,
etc. As shown in Figure 7, the system 10 may also be used in hydroform
applications wherein a
plurality of interlocking members 12 are shaped for placement within a closed
and then
restrained by an attachment means 18 consisting of a self-interlocking
retention piece. In the
particular hydroform embodiment shown in Figure 7, the trigger 20 of the
present invention
consists of a hole or deformation extending through the interior portion of
the interlocking
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members 12 and may further comprise step change in the geometry of the wall
thickness of the
interlocking members 12.
The energy management enhancement system 10 disclosed in the present invention
may be
used in a variety of applications where reinforcement is desired to transfer,
direct, and/or absorb
impact energy that may be applied to structural members of an automotive
vehicle through an
external source or collision to the vehicle. As shown in Figure 9 in a pre-
impact state, the
system 10 may be used to control and direct energy management in frontal
impact testing of
automotive vehicles through targeted bending, buckling, and collapsing of the
system in a
progressive manner while still providing some reinforcement stability in the
bending process
resulting in the system shown in a post-impact state in Figure 10. Namely, as
shown in Figures
9 and 10, axial collapse may be created by opposing or dual bending modes
through the use of
a plurality of triggers 20. The system 10 has particular application in
automotive frame or rail
applications where the overall weight of the structure being reinforced is a
critical factor and
there is a need for reinforcement and/or inhibition of deformation and
distortion resulting from an
impact to the vehicle. For instance, the system 10 may be used to reduce or
inhibit structural
distortion of portions of automotive vehicles, aircraft, marine vehicles,
building structures or
other similar objects that may be subject to an impact or other applied
structural force through
either natural or man-made means. In the embodiment disclosed, the system 10
is used as part
of an automobile frame or rail assembly to inhibit distortion of selected
areas of an automobile
through the transfer and/or absorption of applied energy, and may also be
utilized in conjunction
with rockers, cross-members, chassis engine cradles, roof systems, roof bows,
lift gates, roof
headers, roof rails, fender assemblies, pillar assemblies, radiator/rad
supports, bumpers, body
panels such as hoods, trunks, hatches, cargo doors, front end structures, and
door impact bars
in automotive vehicles as well as other portions of an automotive vehicle
which may be adjacent
to the exterior of the vehicle. The skilled artisan will appreciate that the
system may be
employed in combination with or as a component of a conventional sound
blocking baffle, or a
vehicle structural reinforcement system, such as is disclosed in commonly
owned co-pending
U.S. Application Serial Nos. 09/524,961 or 09/502,686, hereby incorporated by
reference.
Figure 11 shows the U shaped metal reinforcing core 21 to which strips of
structural foam 22, 23
and 24 are attached to the exterior walls by the push pins 25. Also provided
are push pins 26
which can be used to attach the reinforcing member to the internal surface of
the channel to be
reinforced.
Figure 12 shows the part illustrated in Figure 11 located in the lower piece
of the front
longitudinal section 27. When the upper piece of the front longitudinal
section is provided and
welded to the section 27, the pin 26 will attach the reinforcement to the
upper piece whilst
22
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providing a space between the metal 22 and the structural foam 24 and the
inner surface of the
upper piece to allow effective flow of the anticorrosion a coat fluid. After
application of the a coat
fluid the section is baked to cure the coating and the structural foam expands
during the coating
to bond the core to the inner surfaces of the front longitudinal section.
Figure 13 is a schematic illustration of the front rail longitudinal section
shown in Figure 12
showing the rail 27 with two curved sections 28 and 29. The first curved
section being the
curved section furthest away from the front of the vehicle. In this embodiment
no reinforcement
is provided in the second curved section of the front rail, the second curved
section being the
curved section nearer to the front of the vehicle. The reinforcing core member
21 is shown
reinforcing the curved section 28 whereas the curved section 29 has no
reinforcement. Figure
14 shows how, on impact, the reinforcement at section 28 directs the energy so
that deformation
occurs at the curved point 29 rather than also at point 28.
The preferred embodiment of the present invention has been disclosed. A person
of ordinary
skill in the art would realize however, that certain modifications would come
within the teachings
of this invention. Therefore, the following Claims should be studied to
determine the true scope
and content of the invention.
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