U.S. patent application number 11/162349 was filed with the patent office on 2007-03-08 for energy-absorbing device with a reduced initial peak load.
This patent application is currently assigned to FORD MOTOR COMPANY. Invention is credited to Ridha Baccouche, Jamal Bakkar, Hikmat Mahmood, Bill Stanko.
Application Number | 20070052258 11/162349 |
Document ID | / |
Family ID | 37829401 |
Filed Date | 2007-03-08 |
United States Patent
Application |
20070052258 |
Kind Code |
A1 |
Baccouche; Ridha ; et
al. |
March 8, 2007 |
ENERGY-ABSORBING DEVICE WITH A REDUCED INITIAL PEAK LOAD
Abstract
An energy-absorbing device (34) with a reduced initial peak load
(50) for enhancing the management of crash energy in an end
structure (30') for a vehicle (30). The energy-absorbing device
(34) has a deformable construction adapted for progressively
folding along a longitudinal axis (60) under an oscillating crash
load (34'). The oscillating crash load (34') is comprised of a mean
load (48) and a peak load (50) that is in close proximity to the
mean load (48).
Inventors: |
Baccouche; Ridha; (Ann
Arbor, MI) ; Stanko; Bill; (Canton, MI) ;
Bakkar; Jamal; (Dearborn, MI) ; Mahmood; Hikmat;
(Bloomfield Hills, MI) |
Correspondence
Address: |
ARTZ & ARTZ, P.C.
28333 TELEGRAPH ROAD, SUITE 250
SOUTHFIELD
MI
48034
US
|
Assignee: |
FORD MOTOR COMPANY
American Road
Dearborn
MI
|
Family ID: |
37829401 |
Appl. No.: |
11/162349 |
Filed: |
September 7, 2005 |
Current U.S.
Class: |
296/187.03 |
Current CPC
Class: |
B60R 19/34 20130101;
F16F 7/125 20130101; B62D 21/152 20130101 |
Class at
Publication: |
296/187.03 |
International
Class: |
B62D 25/08 20060101
B62D025/08 |
Claims
1-6. (canceled)
7. An energy-absorbing device for an end structure of a vehicle,
comprising: an outer tube attached to a vehicle frame; and an inner
tube within said outer tube and attached to said vehicle frame;
said outer tube and said inner tube having a deformable
construction; said outer tube adapted for progressively folding
along a longitudinal axis under a first oscillating sub-load; said
inner tube adapted for progressively folding along said
longitudinal axis under a second oscillating sub-load; each of said
first oscillating sub-load and said second oscillating sub-load
having a peak sub-load and a cyclic minimum sub-load with said
outer tube receiving said cyclic minimum sub-load when said inner
tube receives said peak sub-load: said first oscillating sub-load
and said second oscillating sub-load comprising a total oscillating
load absorbing crash energy.
8. The energy-absorbing device recited in claim 7 wherein at least
one of said outer tube and said inner tube is defined by a
substantially thin wall.
9. The energy-absorbing device recited in claim 7 wherein said
inner tube has a first end portion and said outer tube has a second
end portion offset from said first end portion of said inner tube
along said longitudinal axis.
10-11. (canceled)
12. The energy-absorbing device recited in claim 7 wherein said
first oscillating sub-load is offset from said second oscillating
sub-load by one-quarter of a wavelength.
13. The energy-absorbing device recited in claim 7 wherein at least
one of said outer tube and said inner tube is comprised of a
substantially lightweight metal.
14. The energy-absorbing device recited in claim 13 wherein said
substantially lightweight material is comprised of aluminum.
15-20. (canceled)
21. An end structure for a vehicle, comprising: a vehicle frame;
said energy-absorbing device recited in claim 7 and attached to
said vehicle frame.
22. The end structure recited in claim 21 wherein said vehicle
frame includes at least two sub-frames with said at least two
deformable members respectfully mounted thereon for providing at
least two load paths.
23. An energy-absorbing device for an end structure of a vehicle,
comprising: an outer tube attached to a vehicle frame; and an inner
tube within said outer tube and attached to said vehicle frame;
said outer tube and said inner tube having a deformable
construction; said outer tube adapted for progressively folding
along a longitudinal axis under a first oscillating sub-load; said
inner tube adapted for progressively folding along said
longitudinal axis under a second oscillating sub-load; each of said
first oscillating sub-load and said second oscillating sub-load
having a peak sub-load and a cyclic minimum sub-load with said
outer tube receiving said cyclic minimum sub-load when said inner
tube receives said peak sub-load; said first oscillating sub-load
and said second oscillating sub-load comprising a total oscillating
crash load for absorbing crash energy; said inner tube adjacent to
said outer tube and reinforcing said outer tube when said outer
tube progressively folds.
24. The energy-absorbing device recited in claim 23 wherein each of
said first oscillating sub-load and said second oscillating
sub-load has a cyclic maximum sub-load with said outer tube
receiving said cyclic maximum sub-load when said inner tube
receives said cyclic minimum sub-load.
25. The energy-absorbing device recited in claim 23 wherein said
inner tube has a first end portion and said outer tube has a second
end portion offset from said first end portion of said inner tube
along said longitudinal axis.
26. The energy-absorbing device recited in claim 23 wherein said
first oscillating sub-load is offset from said second oscillating
sub-load by one-quarter of a wavelength.
27. The energy-absorbing device recited in claim 23 wherein at
least one of said outer tube and said inner tube is defined by a
substantially thin wall.
28. The energy-absorbing device recited in claim 23 wherein at
least one of said outer tube and said inner tube is comprised of a
substantially lightweight metal.
29. The energy-absorbing device recited in claim 28 wherein said
substantially lightweight material is comprised of aluminum.
Description
TECHNICAL FIELD
[0001] The present invention relates generally to energy-absorbing
devices, and more particularly to an energy-absorbing device having
a reduced initial peak load for enhancing the management of crash
energy in a vehicle.
BACKGROUND
[0002] Vehicles having crush zones with one or more
energy-absorbing devices therein have significantly improved the
safety of transportation.
[0003] With attention to FIGS. 1 through 3, there is shown one
known energy-absorbing device comprised of a hollow metal tube 10
adapted for progressively folding in a collision. In particular,
the tube 10 typically yields under an oscillating load with the
formation of successive local buckles 12 along its longitudinal
axis 14. This relationship is exemplified by the load-displacement
curve 16 shown in FIG. 4.
[0004] The load-displacement curve 16 can be generally
characterized by three stages, which include an initial response
18, a primary energy-absorption response 20, and a final response
22.
[0005] In the initial response 18, the tube 10 is elastically
deformed until it receives a peak load 24. Typically, these tubes
10 deform under a sufficiently low peak load 24 for preventing
injuries to the vehicle occupants while safely maximizing the crash
load transferred to them and also maintaining the structural
integrity of the vehicle frame upon which the tubes 10 are
mounted.
[0006] Thereafter, during the primary energy-absorption response
20, the typical tube 10 is plastically deformed under an
oscillating load 26. Each oscillation corresponds to the formation
of one complete buckle 12 in the tube 10. The total displacement of
the tube 10 and the mean value 28 of the oscillating load 26
typically comprise a substantial portion of the crash energy
absorbed by the tube 10. Then, in the final response 22, the tube
10 typically is fully crushed with the load rapidly increasing
therein.
[0007] As shown in FIG. 4, existing tubes 10 typically deform under
a mean load 28 that is substantially lower than the peak load 24,
e.g. less than half of the peak load 24. It is understood that a
tube 10 crushed under a higher mean load can absorb more crash
energy than a tube crushed under a lower mean load.
[0008] Furthermore, existing tubes 10 typically have a somewhat
long construction with a relatively wide cross-section that is
defined by a generally thick wall. In this way, the tubes 10
typically occupy a large space within an end structure of the
vehicle.
[0009] It would therefore be desirable to provide an
energy-absorbing device having an efficiently packaged construction
for improving the management of crash energy.
SUMMARY OF THE INVENTION
[0010] An energy-absorbing device with a reduced initial peak load
for enhancing the management of crash energy in vehicle is
provided. The energy-absorbing device has a deformable construction
adapted for progressively folding along a longitudinal axis under
an oscillating crash load. The oscillating crash load is comprised
of a mean load and a peak load that is in close proximity to the
mean load.
[0011] One advantage of the invention is that an energy-absorbing
device is provided that absorbs a substantial amount of crash
energy in a vehicle and increases the safety of vehicle
occupants.
[0012] Another advantage of the invention is that an
energy-absorbing device is provided that minimizes a peak load
transferred to a vehicle frame and remains securely mounted thereto
during a collision.
[0013] Yet another advantage of the invention is that an
energy-absorbing device is provided that has a substantially
efficient construction for use in small packaging constraints, such
as a front end portion of a compact vehicle.
[0014] Still another advantage of the invention is that an
energy-absorbing device is provided that is sufficiently
lightweight for enhancing the fuel economy of a vehicle having the
energy-absorbing device therein.
[0015] Yet another advantage of the invention is that an
energy-absorbing device is provided that deforms without
conventional triggering mechanisms and thus decreases the
manufacturing cycle time, as well as the costs associated
therewith.
[0016] Other advantages of the present invention will become
apparent upon considering the following detailed description and
appended claims, and upon reference to the accompanying
drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] For a more complete understanding of this invention,
reference should now be made to the embodiments illustrated in
greater detail in the accompanying drawings, namely FIGS. 5 through
13, and described below by way of the examples of the
invention.
[0018] FIG. 1 is a cross-sectional view of a known metal tube for
absorbing crash energy prior to contact with a vehicle or other
barrier.
[0019] FIG. 2 is a cross-sectional view of the tube shown in FIG.
1, illustrating the tube progressively folding during a collision
with a vehicle or other crash barrier.
[0020] FIG. 3 is a cross-sectional view of the tube shown in FIG.
2, illustrating the tube fully crushed.
[0021] FIG. 4 is a graph exemplifying a load-to-displacement
relationship for the conventional metal tube shown in FIGS. 1
through 3.
[0022] FIG. 5 is a perspective view of a vehicle having a front-end
structure with an energy-absorbing device therein, according to one
advantageous embodiment of the claimed invention.
[0023] FIG. 6 is an enlarged perspective view of the
energy-absorbing device shown in FIG. 5.
[0024] FIG. 7 is a lateral cross-sectional view of the
energy-absorbing device shown in FIG. 6.
[0025] FIG. 8A is a longitudinal cross-sectional view of the
energy-absorbing device shown in FIG. 6.
[0026] FIG. 8B is a longitudinal cross-sectional view of the
energy-absorbing device shown in FIG. 6, according to another
advantageous embodiment of the claimed invention.
[0027] FIG. 9 is a cross-sectional view of the energy-absorbing
device shown in FIG. 8A, illustrating the initial impact of a
vehicle or other crash barrier on an outer tube of the
energy-absorbing device.
[0028] FIG. 10 is a cross-sectional view of the energy-absorbing
device shown in FIG. 9, illustrating the outer tube plastically
deforming and being reinforced by an inner tube of the
energy-absorbing device.
[0029] FIG. 11 is a cross-sectional view of the energy-absorbing
device shown in FIG. 10, illustrating further deformation of the
outer tube and the inner tube.
[0030] FIG. 12 is a graph exemplifying a load-to-displacement
relationship for the energy-absorbing device shown in FIGS. 9
through 11.
[0031] FIG. 13 is an enlarged view of the energy-absorbing device
shown in FIG. 10, as taken from within circle 13, illustrating the
inner tube reinforcing the outer tube.
DETAILED DESCRIPTION OF THE INVENTION
[0032] In the following figures, the same reference numerals are
used to identify the same components in the various views.
[0033] The present invention is particularly suited for an
energy-absorbing device for use within a front-end structure of a
vehicle. To that end, the embodiments described herein employ
features where the context permits. However, various other
embodiments are contemplated having different combinations of the
described features, having additional features other than those
described herein, or even lacking one or more of those features.
For instance, it is contemplated that the energy-absorbing device
can be integrated in other portions of a vehicle, in a roadside
barrier, or various other constructions as desired.
[0034] Referring to FIGS. 5 and 6, there is shown a vehicle 30
having a front-end portion 30' comprised of a vehicle frame 32 and
an energy-absorbing device 34, according to one advantageous
embodiment of the claimed invention. As best shown in FIG. 6, the
energy-absorbing device 34 has a substantially compact construction
mounted to the vehicle frame 32 within small packaging constraints.
This feature is beneficial for increasing the available space for
an engine compartment, passenger cabin, or a variety of systems
integrated within the vehicle 30. Moreover, as detailed below, this
construction is also advantageous for absorbing a substantial
amount of crash energy.
[0035] Referring now to FIGS. 7 and 8A, the energy-absorbing device
34 is comprised of an outer tube 36 and an inner tube 38. As
detailed in the description for FIGS. 10 through 12, each tube 36,
38 has an axially-deformable construction adapted for forming
successive local buckles 40 therein under an oscillating crash
load.
[0036] In the embodiment shown in FIG. 8A, the outer tube 36 and
the inner tube 38 provide two load paths. Specifically, the vehicle
frame 32 has a first sub-frame 42 and a second sub-frame 44, which
are independent load-bearing structures. The first sub-frame 42 has
the outer tube 36 attached thereon, and the second sub-frame 44 has
the inner tube 38 attached thereon. Accordingly, the front-end
portion 30' of the vehicle 30 provides two load paths for enhancing
the management of crash energy.
[0037] However, as exemplified in the embodiment shown in FIG. 8B,
it is contemplated that the outer tube 36 and the inner tube 38 can
instead be mounted to the same integral portion of the vehicle
frame 32 as desired.
[0038] Referring now to FIGS. 9 through 11, there is sequentially
illustrated the axial deformation of the energy-absorbing device
34, according to one advantageous embodiment of the claimed
invention. This axial deformation is represented by the
load-displacement graph schematically shown in FIG. 12.
[0039] As shown in FIG. 12, the outer tube 36 and the inner tube 38
deform under respective oscillating sub-loads 36', 38', which
together comprise the total oscillating crash load 34' that axially
collapses the energy-absorbing device 34. In addition, as explained
in the description for FIG. 11, the total oscillating load is
further comprised of a reinforcement load (not shown) that is
provided by the inner tube 38 reinforcing the outer tube 36.
[0040] The oscillating sub-loads 36', 38' in the tubes 36, 38 are
sufficiently out-of-phase for producing the total oscillating crash
load 34' with a substantially high overall mean load 48, e.g. about
15,000 lbf, and an overall peak load 50 in close proximity to the
mean load 48. The high mean load 48 is beneficial for absorbing a
substantial amount of the crash energy. In addition, the overall
peak load 50 is sufficiently low, e.g. only about 25% larger than
the overall mean load 48, for preventing injuries to the vehicle
occupants and maintaining the structural integrity of the vehicle
frame 32.
[0041] However, it is contemplated that the overall peak load 50
can be more or less than twenty-five percent (25%) larger than the
overall mean load 48. Additionally, the overall mean load 48 can be
higher or lower than 15,000 lbf as desired.
[0042] Each oscillating sub-load 36', 38' in the respective tubes
36, 38 has an overall peak sub-load 52a, 54a followed by a cyclic
minimum sub-load 52b, 54b and a cyclic maximum sub-load 52c, 54c.
In this embodiment, the oscillating sub-load 36' in the outer tube
36 is one-quarter of a wavelength out of phase with the oscillating
sub-load 38' of the inner tube 38. In this way, the outer tube 36
deforms under the cyclic minimum sub-load 52b concurrently as the
inner tube 38 deforms under its peak sub-load 54a. It will be
appreciated that this feature is beneficial for providing the
higher overall mean load 48 and minimizing the overall peak load
50.
[0043] As best shown in FIG. 8A, this out-of-phase relationship is
accomplished by offsetting respective end portions 56, 58 of the
outer tube 36 and the inner tube 38 along a longitudinal axis 60 of
the device 34. In particular, the end portion 56 of the outer tube
36 is positioned for receiving the initial crash load before the
end portion 58 of the inner tube 38. Referring back to FIG. 12, the
inner tube 38 is offset a sufficient distance for synchronizing the
peak sub-load 54a of the inner tube 38 with the first cyclic
minimum sub-load 52b of the outer tube 36. Accordingly, the
energy-absorbing device 34 deforms under a reduced overall peak
load 50 and absorbs a substantial amount of the crash energy.
[0044] Also, this offset construction is further beneficial for
deforming without conventional triggering mechanisms therein.
Examples of the conventional triggering mechanisms include
indentations, deep wrinkles, and other known stress risers formed
in the tube's perimeter. For this reason, the device 34 eliminates
the need for the manufacturing processes, which would otherwise be
required for forming the triggering mechanisms in the tubes 36, 38.
Accordingly, the offset construction of the device 34 decreases the
manufacturing cycle time and the costs associated therewith.
However, it is understood that the tubes 36, 38 can instead have
stress risers as desired.
[0045] It is contemplated that the outer tube 36 can instead be
offset from the inner tube 38 in a variety of other suitable ways
for reducing the overall peak load 50 and/or triggering deformation
therein. Also, it is understood that the outer tube 36 and/or the
inner tube 38 can have various other suitable constructions that
deform under a peak load 50 in close proximity to the mean load 48.
Moreover, it will be appreciated that more than two tubes 36, 38 or
equivalents thereof can be utilized as desired and otherwise
positioned as desired.
[0046] Furthermore, with attention to the embodiment shown in FIGS.
10 and 13, the inner tube 38 is sufficiently offset inwardly from
the outer tube 36 for contacting and strengthening the outer tube
36 as the outer tube 36 progressively folds. Namely, as best shown
in FIG. 13, the inner tube 38 can sufficiently support the outer
tube 36 and minimize deep-stage collapse 62 in each successive
buckle 40 or fold. In this regard, the inner tube 38 minimizes the
valley amplitude of the overall crash load 34' and strengthens the
overall energy-absorbing device 34.
[0047] With attention to FIG. 8A, each tube 36, 38 has a
substantially thin-wall box construction for progressively folding
along the longitudinal axis 60. For example, the wall of each tube
36, 38 is one (1) to three (3) millimeters thick. However, the wall
of each tube 36, 38 can be higher or lower than this range so long
as the purposes of the claimed invention are accomplished.
[0048] It will be appreciated that an otherwise sufficiently
thicker wall may not progressively fold and therefore may absorb
less crash energy. For instance, a sufficiently thicker wall may
peel outwardly instead of folding with successive bellows similar
to an accordion. However, it is contemplated that the
energy-absorbing device 34 can have various other suitable
constructions for deforming in a variety of ways.
[0049] Also, in this embodiment, the outer tube 36 and the inner
tube 38 are comprised of aluminum. In this respect, the
energy-absorbing device 34 is sufficiently strong for absorbing a
high amount of crash energy and also significantly lightweight for
enhancing the fuel economy of the vehicle 30. It is understood that
the outer tube 36 and the inner tube 38 can be comprised of a
variety of other suitable materials.
[0050] While particular embodiments of the invention have been
shown and described, it will be understood, of course, that the
invention is not limited thereto since modifications may be made by
those skilled in the art, particularly in light of the foregoing
teachings. Accordingly, it is intended that the invention be
limited only in terms of the appended claims
* * * * *