U.S. patent application number 12/940680 was filed with the patent office on 2012-03-15 for energy absorber with lobes providing uniform pedestrian impact.
Invention is credited to Alexander Besch, Darin Evans, Yassine Ghozzi, Olaf Insel, Oliver Knoke, Amit Ashok Kulkarni, Ngoc-Dang Nguyen, Daniel Ralston, Vidya Revankar.
Application Number | 20120061978 12/940680 |
Document ID | / |
Family ID | 43970786 |
Filed Date | 2012-03-15 |
United States Patent
Application |
20120061978 |
Kind Code |
A9 |
Ralston; Daniel ; et
al. |
March 15, 2012 |
ENERGY ABSORBER WITH LOBES PROVIDING UNIFORM PEDESTRIAN IMPACT
Abstract
A bumper system includes an injection molded energy absorber of
polymeric material having hollow longitudinally-spaced lobes
configured to crush and absorb energy during a pedestrian impact,
and straps interconnecting adjacent lobes. The lobes are
particularly sized and dimensioned, including potentially external
ribs and/or apertures in corners, to provide a relatively uniform
impact energy absorption during an impact stroke during crush of
the shear walls of the lobes, such as within +/-30% or more
preferably within +/-20% of a desired amount regardless of a
specific location of impact, along a selected center portion of the
energy absorber. A reason for the uniformity is to promote
pedestrian safety regardless of the specific location where a
pedestrian's leg strikes the energy absorber.
Inventors: |
Ralston; Daniel; (Walker,
MI) ; Revankar; Vidya; (Grand Haven, MI) ;
Kulkarni; Amit Ashok; (Grand Haven, MI) ; Evans;
Darin; (Spring Lake, MI) ; Insel; Olaf;
(Rothemuhle, DE) ; Ghozzi; Yassine; (Wolfsburg,
DE) ; Besch; Alexander; (Gifhorn, DE) ; Knoke;
Oliver; (Braunschweig, DE) ; Nguyen; Ngoc-Dang;
(Wolfsburg, DE) |
Prior
Publication: |
|
Document Identifier |
Publication Date |
|
US 20110109105 A1 |
May 12, 2011 |
|
|
Family ID: |
43970786 |
Appl. No.: |
12/940680 |
Filed: |
November 5, 2010 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61258653 |
Nov 6, 2009 |
|
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Current U.S.
Class: |
293/132 |
Current CPC
Class: |
B60R 2021/343 20130101;
B60R 19/18 20130101; B60R 2019/1893 20130101; B60R 2019/1873
20130101 |
Class at
Publication: |
293/132 |
International
Class: |
B60R 19/34 20060101
B60R019/34 |
Claims
1. A bumper system for a vehicle having a longitudinal direction,
the bumper system having corners defined by vertical planes
oriented at 60.degree. to the longitudinal direction and engaging a
front of the bumper system, the bumper system further having a
"bumper test area" defined about 66 mm inboard of each of the
corners but excluding a center region of 250 mm of the bumper
system, comprising: a bumper reinforcement beam configured for
attachment to a vehicle frame; and an energy absorber positioned on
a face of the beam, the energy absorber including a plurality of
spaced-apart hollow crush lobes in the bumper test area that are
configured to crush and absorb energy during a pedestrian impact,
the lobes being configured to provide a uniform impact energy
absorption during crush of within +/-30% of a desired average
impact energy absorption force-deflection profile for impact
intrusions that crush the crush lobes at least 10 mm in
longitudinal locations along a length of the "bumper test area,"
whereby the bumper system provides for pedestrian safety regardless
of a specific location where a pedestrian's leg strikes the energy
absorber.
2. The bumper system defined in claim 1, wherein the lobes include
shear walls configured to crush and absorb a predictable amount of
energy when impacted.
3. The bumper system defined in claim 2, wherein the shear walls
include a pair of opposing vertical shear walls.
4. The bumper system defined in claim 2, wherein the shear walls
include a pair of opposing horizontal shear walls.
5. The bumper system defined in claim 2, wherein a force of
resistance provided by the shear walls remains relatively constant,
within +/-30%, during a working portion of the impact stroke, the
working portion being when the shear walls of the lobes are
crushing and folding in a manner absorbing energy.
6. The bumper system defined in claim 5, wherein a force of
resistance provided by the shear walls remains relatively constant,
within +/-20%, during the working portion of the impact stroke.
7. The bumper system defined in claim 1, wherein a force of
resistance provided by the lobes during the pedestrian impact is
relatively constant during an impact stroke in the range of 30 mm
to 60 mm intrusion.
8. The bumper system defined in claim 1, wherein the energy
absorber is made of a polymeric material.
9. The bumper system defined in claim 1, wherein the energy
absorber is injection molded.
10. The bumper system defined in claim 1, wherein the lobes include
lobe centerlines, and the lobe spacing between lobe centerlines is
between 90 mm to 132 mm.
11. The bumper system defined in claim 10, wherein the lobe spacing
between the lobe centerlines is between 100 mm and 120 mm.
12. The bumper system defined in claim 1, wherein each of the lobes
includes vertical shear walls that are spaced 65 mm to 90 mm apart,
and wherein each adjacent pair of the lobes include adjacent
vertical shear walls that are spaced 15 mm to 30 mm apart at a base
of the shear walls.
13. The bumper system defined in claim 1, wherein the lobes, when
in a vehicle-mounted position, have a lobe height of 60 mm
+/-30%.
14. The bumper system defined in claim 1, wherein the lobes, when
in a vehicle-mounted position, includes a depth of between about 40
mm and 100 mm.
15. The bumper system defined in claim 1, wherein the lobes, when
in a vehicle-mounted position, include vertical shear walls having
a crown of at least 200 mm radius curvature.
16. The bumper system defined in claim 1, wherein the lobes, when
in a vehicle-mounted position, include horizontal shear walls
having a crown of at least 200 mm radius curvature.
17. The bumper system defined in claim 1, wherein the lobes
includes walls having a thickness of 1.5 mm to 2.8 mm.
18. The bumper system defined in claim 1, wherein the lobes include
walls having at least one of undulations and ribs extending along
at least one of the walls.
19. The bumper system defined in claim 1, wherein the lobes include
radii of about 2 mm-10 mm along corners and at joints of the
walls.
20. An energy absorber configured to be positioned on a face of a
structural member for absorbing energy during an impact against the
structural member, the energy absorber comprising: a base flange
configured to engage a reinforcement beam and including a plurality
of spaced-apart hollow lobes extending from a base flange, the
energy absorber defining a test area including at least three
adjacent hollow lobes but excluding end sections of the energy
absorber and excluding a center region of about 250 mm, the lobes
each having shear walls configured to crush and absorb energy when
impacted, the base flange including straps interconnecting adjacent
lobes, the lobes and straps in the test area being configured,
sized and spaced to provide a uniform impact energy absorption
during crush of within +/-30% of a desired average impact energy
absorption force-deflection profile for impact intrusions of at
least 10 mm in longitudinal locations along a length of the "test
area" for pedestrian safety regardless of the specific location
where an impactor strikes the energy absorber, the lobes in the
test area having centerlines spaced longitudinally between 90 mm to
132 mm apart.
21. The energy absorber defined in claim 20, wherein the lobes each
include opposing vertical shear walls.
22. The energy absorber defined in claim 21, wherein the lobes each
include opposing horizontal shear walls.
23. The energy absorber defined in claim 20, wherein the energy
absorber is made of a polymeric material.
24. The energy absorber defined in claim 20, wherein the energy
absorber is made of a metal material.
25. The energy absorber defined in claim 20, wherein the lobes have
centerlines spaced longitudinally between 100 mm to 120 mm
apart.
26. An energy absorber configured to be positioned on a face of a
beam, the energy absorber comprising: a base flange; at least one
hollow lobe extending from the base flange and having top and
bottom shear walls and vertical shear walls that join to define
four corners, and having at least one aperture strategically
located at a base of each corner, the at least one aperture
extending partially around each respective corner and into the
associated adjacent walls to reduce columnar strength of the
respective corner, the shear walls and apertures being shaped and
sized to cause a predictable and uniform impact resistance to a
pedestrian's leg regardless of a specific location where the
pedestrian's leg strikes the energy absorber, the impact resistance
being uniform to within +/-30% of a desired force deflection
profile during impacts crushing more than 10 mm the at least one
hollow lobe to absorb energy.
27. The energy absorber defined in claim 26, wherein the impact
resistance is relatively constant to within +/-30% of a constant
force of resistance during impact intrusions of 30 mm to 60 mm as
the at least one hollow lobe crushes during the impact.
28. The energy absorber defined in claim 26, wherein the lobes
include lobe centerlines, and where the lobe centerlines are
between 90 mm and 132 mm apart.
29. The energy absorber defined in claim 26, wherein the at least
one lobe includes at least two lobes, each being a same size and
shape.
30. The energy absorber defined in claim 26, wherein the at least
one lobe includes at least two lobes, each having an external rib
positioned on top and bottom walls in locations spaced inward from
sides of the at least two lobes.
31. The energy absorber defined in claim 26, wherein the at least
one lobe is made of polymeric material.
32. The energy absorber defined in claim 26, wherein the at least
one lobe is made of metal material.
33. An energy absorbing system for a vehicle, comprising: a
structural member configured for attachment to a vehicle; and an
energy absorber positioned on a face of the structural member, the
energy absorber having at least four hollow crush lobes defining a
test area and when impacted defining a working portion of a
force-deflection curve where the crush lobes collapse to absorb
energy, the crush lobes being longitudinally spaced apart and
configured to provide a uniform impact energy absorption during the
working portion of the force-deflection curve of within +/-30% of a
desired average impact energy absorption force-deflection profile
in locations along a length of the test area.
34. The energy absorbing system defined in claim 33, wherein the
crush lobes are configured to provide a uniform impact energy
absorption within 30% of a desired average impact energy absorption
value at a 30 mm to 60 mm impact intrusion in all longitudinal
locations along a length of the at least four hollow crush
lobes.
35. The energy absorbing system defined in claim 33, wherein the
structural member includes a bumper reinforcement beam.
36. The bumper system defined in claim 33, wherein the energy
absorber is made of a polymeric material.
37. A method comprising steps of: providing an energy absorber with
a base flange configured to engage a support structure and
including spaced-apart hollow lobes extending from the base flange
and defining a test area; the lobes each including shear walls
configured to crush and absorb energy along a force deflection
profile when impacted by a pedestrian-leg-simulating impactor for
an intrusion stroke causing collapse of the hollow lobes of at
least 10 mm; and tuning the crush lobes of the energy absorber to
improve uniformity of energy absorption to within +/-30% of a
desired average energy absorption profile regardless of a specific
location of impact by the impactor along the test area of the
energy absorber by forming at least one of apertures and external
ribs on the crush lobes, where the ribs, if present, are located on
shear walls of the crush lobes and where the apertures, if present,
are located at corners formed by adjacent ones of the shear walls,
to thus provide uniform performance and pedestrian safety
regardless of a specific location where a pedestrian's leg strikes
the energy absorber.
Description
[0001] This application claims benefit under 35 U.S.C. Section
119(e) of provisional application Ser. No. 61/258,653, filed Nov.
6, 2009, entitled ENERGY ABSORBER WITH LOBES REDUCING PEDESTRIAN
INJURY, the entire contents of which are incorporated herein in
their entirety.
BACKGROUND
[0002] The present invention relates to vehicle bumper systems
having energy absorbers, where the energy absorbers have hollow
crush lobes constructed to collapse upon impact at predetermined
rates of resistance and energy absorption.
[0003] Modern vehicle bumpers often include polymeric energy
absorbers positioned on a face of a metal reinforcement beam and
that are adapted to absorb impact energy. These energy absorbers
often have forwardly-projecting hollow lobes (also called "crush
boxes") that are elongated horizontally and where adjacent lobes
are interconnected by straps. The lobes are often hollow "box
shaped" structures that, when in a vehicle mounted position,
include top and bottom horizontal shear walls, right and left
vertical shear walls, and a front wall. However, this concept of
spaced-apart elongated box-shaped lobes leads to inconsistent
energy absorption across a length of the bumper system and thus
varied performance depending on where a pedestrian's leg strikes
the energy absorber.
[0004] For example, if a pedestrian's leg contacts the energy
absorber between lobes during an impact, it will likely encounter
two vertical shear walls (i.e. the two shear walls on either side
of a particular strap, see the left leg impactor in prior art in
FIG. 2), which generates a relatively higher force of impact
against the leg. Also, if the leg contacts the energy absorber at a
center of a lobe, the leg basically misses any vertical shear wall
(see the right leg impactor in prior art in FIG. 2), and hence the
rate of energy absorption during impact will be substantially
lower. Notably, it is not at all clear what spacing or position or
shape of the shear walls (i.e. walls that crush and absorb energy
during an impact) on an energy absorber will give a best result,
especially given the different densities and materials (i.e. bone,
flesh, skin) within a pedestrian's leg and the roundness of a
leg.
[0005] Notably, the impact against a pedestrian's leg is complex
and difficult to replicate, such that various government and
insurance companies have developed a standardized pedestrian leg
impacting device (also called "standardized leg impactor") for use
when conducting pedestrian impact testing. Specifically, a
committee of the United Nations called UNECE has propagated a
standard using a pedestrian-leg-simulating impactor 50 (see FIG.
2). The impactor 50 has a center core 51 that is a 70 mm diameter
steel rod (which represents "bone"), surrounded by a 25 mm thick
foam layer 52 (which represents "flesh"), and that is then wrapped
in a 6 mm thick neoprene sleeve 53 (which represents "skin"),
producing a total diameter of 132 mm. Since different densities are
included through its interior, it is not at all clear what size or
shape of lobe, nor spacing of shear walls or lobes, should be
optimally provided in energy absorbers for a most uniform "best"
resistance profile.
[0006] For the above reasons, improvements in energy absorbers with
hollow crush lobes are needed to provide both reliable and
predictable pedestrian impact characteristics across a length of
the energy absorber as well as to provide desired impact
characteristics for more severe impacts.
SUMMARY OF THE INVENTION
[0007] In one aspect of the present invention, a bumper system is
provided for a vehicle having a longitudinal direction, the bumper
system having corners defined by vertical planes oriented at
60.degree. to the longitudinal direction and engaging a front of
the bumper system, the bumper system further having a "bumper test
area" defined about 66 mm inboard of each of the corners but
excluding a center region of 250 mm of the bumper system. The
bumper system includes a bumper reinforcement beam configured for
attachment to a vehicle frame, and an energy absorber positioned on
a face of the beam. The energy absorber includes a plurality of
spaced-apart hollow crush lobes in the bumper test area that are
configured to crush and absorb energy during a pedestrian impact.
The lobes are configured to provide a uniform impact energy
absorption during crush of within +/-30% of a desired average
impact energy absorption force-deflection profile for impact
intrusions that crush the crush lobes at least 10 mm in
longitudinal locations along a length of the "bumper test area". By
this arrangement, the bumper system provides for pedestrian safety
regardless of a specific location where a pedestrian's leg strikes
the energy absorber.
[0008] In another aspect of the present invention, an energy
absorber is configured to be positioned on a face of a structural
member for absorbing energy during an impact against the structural
member, the energy absorber including a base flange configured to
engage a reinforcement beam and including a plurality of
spaced-apart hollow lobes extending from a base flange. The energy
absorber defines a test area including at least three adjacent
hollow lobes but excluding end sections of the energy absorber and
excluding a center region of about 250 mm. The lobes each have
shear walls configured to crush and absorb energy when impacted,
and the base flange includes straps interconnecting adjacent lobes.
The lobes and straps in the test area are configured, sized and
spaced to provide a uniform impact energy absorption during crush
of within +/-30% of a desired average impact energy absorption
force-deflection profile for impact intrusions of at least 10 mm in
longitudinal locations along a length of the "test area" for
pedestrian safety regardless of the specific location where an
impactor strikes the energy absorber. The lobes in the test area
have centerlines spaced longitudinally between 90 mm to 132 mm
apart.
[0009] In another aspect of the present invention, an energy
absorber is configured to be positioned on a face of a beam. The
energy absorber comprises a base flange, and at least one hollow
lobe extending from the base flange and having top and bottom shear
walls and vertical shear walls that join to define four corners.
There is at least one aperture strategically located at a base of
each corner, the at least one aperture extending partially around
each respective corner and into the associated adjacent walls to
reduce columnar strength of the respective corner. The shear walls
and apertures are shaped and sized to cause a predictable and
uniform impact resistance to a pedestrian's leg regardless of a
specific location where the pedestrian's leg strikes the energy
absorber, the impact resistance being uniform to within +/-30% of a
desired force deflection profile during impacts crushing more than
10 mm the at least one hollow lobe to absorb energy.
[0010] In another aspect of the present invention, an energy
absorbing system for a vehicle includes a structural member
configured for attachment to a vehicle; and an energy absorber
positioned on a face of the structural member. The energy absorber
has at least four hollow crush lobes defining a test area and when
impacted defining a working portion of a force-deflection curve
where the crush lobes collapse to absorb energy. The crush lobes
are longitudinally spaced apart and configured to provide a uniform
impact energy absorption during the working portion of the
force-deflection curve of within +/-30% of a desired average impact
energy absorption force-deflection profile in locations along a
length of the test area.
[0011] In another aspect of the present invention, a method
comprising steps of providing an energy absorber with a base flange
configured to engage a support structure and including spaced-apart
hollow lobes extending from the base flange and defining a test
area; the lobes each including shear walls configured to crush and
absorb energy along a force deflection profile when impacted by a
pedestrian-leg-simulating impactor for an intrusion stroke causing
collapse of the hollow lobes of at least 10 mm. The method further
includes tuning the crush lobes of the energy absorber to improve
uniformity of energy absorption to within +/-30% of a desired
average energy absorption profile regardless of a specific location
of impact by the impactor along the test area of the energy
absorber by forming at least one of apertures and external ribs on
the crush lobes, where the ribs, if present, are located on shear
walls of the crush lobes and where the apertures, if present, are
located at corners formed by adjacent ones of the shear walls, to
thus provide uniform performance and pedestrian safety regardless
of a specific location where a pedestrian's leg strikes the energy
absorber.
[0012] These and other aspects, objects, and features of the
present invention will be understood and appreciated by those
skilled in the art studying the following specification, claims and
appended drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] FIGS. 1-3 show a prior art bumper system, FIG. 1 being a top
view, FIG. 2 being a fragmentary top view minus fascia and also
showing a pedestrian-leg-simulating impactor 50, and FIG. 3 being a
cross sectional view.
[0014] FIGS. 4-9 are perspective, enlarged fragmentary perspective,
top, front, rear perspective and bottom views of a bumper system
embodying the present invention, FIGS. 4 and 6 showing the
reinforcement beam and energy absorber, and FIGS. 4-9 showing the
energy absorber constructed to provide uniform pedestrian impact
resistance across its pedestrian impact area.
[0015] FIGS. 10-12 are cross sectional views, FIG. 10 being an
enlarged cross section in the circled area X in FIG. 9, FIGS. 11-12
being cross sections taken along lines XI-XI and XII-XII in FIG.
10.
[0016] FIG. 13 is an enlarged cross section similar to FIG. 11 but
showing the energy absorber attached to the beam like I shown in
FIG. 4.
[0017] FIG. 14 is a top view similar to FIG. 6 but showing the
energy absorber attached to a beam and being struck in three
different locations by a pedestrian-leg-simulating test
impactor.
[0018] FIG. 15 is a graph showing force versus displacement curves
for a bumper system embodying the present invention at six
different locations spaced longitudinally 11 mm from each other,
the bumper system being the system shown in FIGS. 4-14.
[0019] FIGS. 16-17 are graphs showing force versus displacement
curves for two prior art bumper systems, each having a prior art
energy absorber on a prior art reinforcement beam, FIG. 16 being an
injection molded energy absorber and FIG. 17 including a metal
energy absorber.
[0020] FIGS. 18-20 are graphs showing force versus displacement
curves for bumper systems of the present invention having an
identical reinforcement beam and a similar energy absorber with
identical shaped, spaced lobes, but where the walls of the lobes in
FIGS. 18-20 have different thicknesses and/or different apertures
at corners to improve consistency of impact strength across their
front section and to cause a different max impact-resistive force
over an impact stroke of 30 mm to 70 mm, the lobes in each of FIGS.
18-20 being 60 mm deep, and each graph showing two impacts where a
greatest difference is expected in force of resistance.
[0021] FIGS. 21-23 and 24-26 are graphs similar to FIGS. 18-20, but
in FIGS. 21-23 the depth of lobes is 70 mm, and in FIGS. 24-26 the
depth of lobes is 80 mm.
[0022] FIG. 27 is a perspective view of a section of a modified
energy absorber with holes and
[0023] FIG. 28 is a force versus displacement curve for a bumper
system including the energy absorber of FIG. 27.
[0024] FIG. 29 is a perspective view of a section of a modified
energy absorber similar to FIG. 27 but with apertures at
corners.
[0025] FIG. 30 is a perspective view of a section of a modified
energy absorber similar to FIG. 29 (i.e. no corner apertures) and
including exterior ribs to stabilize top and bottom side walls of
the crush lobes, and FIG. 31 is a force versus displacement curve
for a bumper system including the energy absorber of FIG. 27.
[0026] FIG. 32 is a cross-sectional view similar to FIG. 13 but
including a modified energy absorber.
DESCRIPTION OF PRIOR ART
[0027] FIGS. 1-3 illustrate one type of prior art bumper system
including a bumper reinforcement beam 100 (see FIGS. 2-3) and a
polymeric energy absorber 101 on its face surface, covered by an
aesthetically colored fascia 102 (e.g. RRIM, injection molded TPO
or other material). The energy absorber 101 abuts the face surface
and includes energy-absorbing crush lobes 103 with walls configured
to crush and absorb energy upon impact. The walls include vertical
shear walls 104. The illustrated lobes 103 are elongated parallel a
length of the beam, and have a length significantly longer than
that of a pedestrian's leg (illustrated by a standard leg impactor
50), such that their impact resistance varies widely depending on a
location of impact. When a pedestrian's legs (illustrated by
impactor 50) is impacted at location M (FIG. 2) (i.e. where the
impact is centered between adjacent lobes), the leg receives a
relatively higher impact resistance from two vertical shear walls
104. However, when impacted at location N (i.e. the impact is
centered on a single lobe), the leg receives a relatively lower
impact resistance (i.e. virtually no impact resistance from any
vertical shear wall). This is because the lobe is elongated, such
that there is no close vertical shear wall to location N. This
condition results in inconsistent and unpredictable impact energy
absorption when a pedestrian is impacted.
[0028] One organization that evaluates pedestrian impact is the
UNECE, a committee in the United Nations (UN), which has released
Global Technical Regulation (GTR) No. 9. This is in the process of
being adopted by member nations and once adopted in each individual
country, this will be a regulation. The pedestrian impact criteria
primarily apply to a front section of a bumper system located
between corners of the vehicle, because that is where pedestrian
impacts are often struck and cause greatest injury.
[0029] In UNECE's Global Technical Regulation No. 9, a "corner of a
bumper" is established by the vehicle's point of contact with a
vertical plane which makes an angle of 60 degrees with the vertical
longitudinal plane of the vehicle and is tangential to the outer
surface of the bumper. (See FIGS. 1 and 6.) A "bumper test area"
BTA (also called herein "pedestrian-impact bumper test area" as
used for assessing pedestrian impact) is then established in a zone
between locations 66 mm inboard of the "corners." Specifically, the
"bumper test area" means the frontal surface of the bumper limited
by two longitudinal vertical planes VP intersecting the corners of
the bumper and moved 66 mm parallel and inboard of the corners of
the bumper.
[0030] The standardized test fixture (impactor 50) (see FIGS. 2 and
14) (also called a "pedestrian leg impactor") is used in bumper
impact testing under Regulation No. 9 to simulate impacts against a
"typical" pedestrian's leg. It includes an internal steel rod 51
(i.e. "bone") of 70 mm diameter, a cylinder of foam 52 (i.e.
"flesh") forming a tube of 25 mm thickness around the rod 51 to
thus form an outer diameter of 120 mm, and a sleeve 53 (i.e.
"skin") forming a tube of 6 mm thickness around the foam 52 to thus
form an outer diameter of about 132 mm.
[0031] FIGS. 16-17 illustrate force versus deflection curves for
two prior art bumper systems with prior art energy absorbers tested
to define a benchmark for uniformity of their resistive forces
across their length in the "bumper test area" defined above, one
being polymeric material and the other being made of metal. As
shown, the resistive forces varied by as much as about 150% to 400%
at a crush/intrusion of about 30 mm, depending on where the impact
occurred along the bumper system. For example, in the prior art
bumper system with energy absorber tested in FIG. 16, at 30 mm
intrusion, the resistive force (depending on where struck) was as
little as about 1000 N or as high as about 5000 N. Further in FIG.
16, noticeable significant differences in the amount of resistive
forces become apparent as low as 10 mm intrusion, and dramatic
differences were noted above 30 mm to 60 mm intrusion. In the prior
art bumper system with energy absorber tested in FIG. 17, at 30 mm
intrusion, the resistive force was as little as about 1700 N or up
to about 4300 N. Again, the amount of resistive forces starts to be
significant and different as low as 10 mm intrusion or lower, and
significant at intrusions above 30 mm to 60 mm.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENT
[0032] In the present description, various terms are used to
facilitate a description, such as height, width, length, upper,
lower, right, left, and etc. These terms are used to facilitate the
description, but are not intended to be unnecessarily limiting.
Further, it is noted that sometimes the terms refer to the part in
a vehicle-mounted orientation (where the lobes face
horizontally/forwardly), while other times the terms are used to
refer to the energy absorber laying on a rest surface such as a
table (with the lobes facing upwardly).
[0033] A vehicle bumper system 20 (FIGS. 4-6) includes a
reinforcement beam 21 mounted to a vehicle frame by mounts 22, and
an energy absorber 23 on its face, covered by a fascia (see the
fascia 23A in FIG. 2). The illustrated energy absorber 23 (FIGS.
6-10) is injection molded of polymeric material and includes hollow
longitudinally-spaced energy-absorbing lobes 24 (also called "crush
boxes") and co-planar straps 25 (coplanar with and forming part of
base flange 27) interconnecting the lobes 24 that abut the face. We
have found that if the energy absorber 23 includes energy-absorbing
crush lobes 24 having a lobe longitudinal spacing (dimension DLS)
set between a centerline spacing of about 90 mm to about 132 mm
(and more preferably 100 mm to 120 mm, and most preferably about
110 mm), and strap widths (measured in a longitudinal direction of
the bumper beam) of between about 15 mm and 50 mm (and more
preferably about 20 mm to 45 mm, or most preferably between 30 mm
to 40 mm), that the performance is significantly more consistent,
independent of an impact location.
[0034] For example, an energy absorber (such as energy absorber 23
with lobes 24) made using the present innovation can be constructed
to provide a uniform impact force of resistance in a range of
within +/-30% (or more preferably within a range of 25%, and most
preferably within a range of 20% to as low as 10% variation) of a
desired average impact energy-absorption profile across its bumper
impact area for an impact stroke of greater than 10 mm up to 40 mm
or more. One optimal energy absorber range would be where a spacing
between lobe centers is a dimension A, and where a depth of a given
lobe is a dimension B, and where a ratio of A:B is equal to about
110:65 within a range of +/-20%.
[0035] It is noted that, in the present innovation, the entire
bumper test area may have a uniform impact energy-absorption
profile. However, it is also contemplated that many times the
energy absorber will not have uniformity across a center region of
the bumper test area, and therefore a scope of the present
invention is contemplated to include this possibility.
Specifically, the absence of uniformity in a center region of an
energy absorber in a bumper system may be due to a variety of
different reasons. For example, pedestrians are not usually struck
by a center of the bumper test area due to their effort to get out
of the way of the vehicle immediately prior to impact. Further, a
license plate attached to the center region of the bumper system
may change the impact result, such that a requirement of uniformity
is nonsensical. Also, other structural features may be located at a
center of the bumper system that may make a requirement of
uniformity in the center region nonsensical. Thus, the requirement
of uniformity of impact energy absorption profile may exclude a
center region of an energy absorber in the present innovative
bumper system for a distance of about 250 mm, or more preferably
for a distance of about 200 mm.
[0036] Our testing shows us that a depth of the crush lobes 24
(measured from the base flange at the bumper beam's face surface to
a tip of the crush lobe when in a vehicle-mounted position) can be
varied as required by package space on the vehicle and as allowed
by the OEM vehicle manufacturer for impact stroke. For example, a
depth of the crush lobes can be about 50-90 mm, or more preferably
about 55 mm-80 mm. The present innovation allows the uniformity to
be extended to different crush strokes, as shown in FIGS. 16-24 and
discussed below.
[0037] Our testing shows us that a vertical height of the crush
lobes (24) (i.e. a vertical dimension when the energy absorber is
in a vehicle-mounted position) is not as important as lobe spacing
and lobe width. However, generally stated, a preferred lobe height
(measured in a fore-aft direction when in a vehicle-mounted
position and measured at a middle point on the exterior surface of
the shear walls) is about 50 mm to 90 mm, and more preferably about
60 mm-80 mm.
[0038] Our testing shows that a wall thickness of shear walls and
front (face) wall in lobes 24 affects a strength and uniformity of
impact resistance. Preferably, the energy absorber 23 is made of
injection molded polypropylene or TPO material, and made to include
a top and bottom (horizontal) shear wall (45,46) having a wall
thickness of about 1.5 mm-2.8 mm (or more preferably a wall
thickness of about 1.75 mm-2.4 mm), and to include vertical shear
walls (47,48) having a wall thickness of about 1.5 mm-2.8 mm (or
more preferably a wall thickness of about 1.75 mm-20 mm), and to
include a front (face) wall (49) having a wall thickness of about
1.5 mm-2.8 mm (or more preferably a wall thickness of about 1.75
mm-2.0 mm). It is noted that the shear walls (47,48) (top, bottom
and sides) may vary in wall thickness due to a draft angle that
facilitates molding. Notably, the illustrated shear walls (45-48)
have a slight crown or curvature (in a fore-aft direction when
mounted to a vehicle), such as 200 mm to 350 mm radius (also called
a "crown"). However, it is contemplated that the shear walls can
have an infinite radius crown (i.e. a flat wall), or can have
another non-linear shape. As used herein, a "crown" in a vertical
shear wall means a radius about a vertical axis spaced a radial
distance from the shear wall and on the concave side of the wall. A
"crown" in a horizontal shear wall means a radius about a
horizontal axis spaced a radial distance from the shear wall and on
the concave side of the wall.
[0039] The corners formed by lobe walls (45-49) can adversely
affect localized energy absorption during lobe crush due to their
columnar strength, thus causing spikes in loading at impact
locations aligned with one of the vertical shear walls 47 or 48.
Concurrently, a shape of corners also affects uniformity of energy
absorption across the energy absorber in the bumper impact area.
The illustrated lobes 24 are radiused along all corners to
facilitate injection molding, as evidenced by the curved corners
found at the juncture along/between any two of the walls 45-49 and
base flange 27 and straps 25. A cross section transversely through
the preferred shape of corners typically defines a radius of about
2 mm-8 mm, or more preferably a radius of about 3 mm-6 mm radius,
or most preferably a radius of about 3 mm-5 mm. Nonetheless, it is
noted that the present invention can be used on lobe
structures/corners having narrower or greater radii or curvilinear
shapes, or corners with other shapes. It is noted that in the data
referring to a width of straps (e.g. for example "20 mm width"),
the strap width includes the flat portion (i.e. for example about
15 mm) of the strap and also includes about half of the radiused
corner on each side (i.e. about an additional 3 mm on each side,
based on the procedure that we used to measure same). A remainder
of the corner radius becomes part of the side wall (45-48) for
purposes of the present discussion, although it is noted that the
discussion herein primarily refers to centerline spacing of the
lobes, and usually does not refer to spacing of vertical shear
walls on a given lobe nor between lobes 24.
[0040] A uniformity of the frontal impact can be improved by
reducing "columnar" stiffness in specific areas where the impact
force is undesirably high above the desired average impact
strength, including providing a weakening structure (sometimes
called a "crush initiator"), such as an aperture 60 (FIG. 5) or
opening at a bottom of the corners of each lobe 24 or at junctures
of walls, or at an apertures 61 at a top of the vertical shear
walls 47-48, as described below. In other words, apertures 60,61
act to reduce columnar and wall stiffness at locations having an
undesirably high stiffness, and that otherwise would cause a
location-specific load spike. For example, the aperture 60 is
included at the bottom of each of the four corners defined by four
shear walls 45-48 and the beam-abutting strap 25/base flange 27.
Also, apertures 61 (FIG. 5) may be advantageously included at the
outer edges of the front face wall 49 at a center location on each
of the vertical shear walls 47,48. It is contemplated that the
apertures 60 and 61 can be any size or shape, but our testing shows
that rectangular apertures work well, with the aperture extending
across the corner and into the two or three adjacent walls forming
the corner.
[0041] Often a uniformity of the frontal impact can be improved by
increasing stiffness of the lobes 24 in specific areas where the
impact force is undesirably low compared to the desired average
impact strength. For example, this can be done by providing
external ribs 62 on the top and bottom shear walls 47, 48 (FIG.
30), thus stiffening the top and bottom shear walls 47,48, as
discussed below in regard to energy absorber 23D (FIG. 30).
[0042] The illustrated energy absorber 23 (FIGS. 6-10) includes a
base flange 27 from which the lobes 24 extend forwardly, and
further include rearwardly-extending top and bottom attachment
flanges 28 spaced along top and bottom edges of the base flange 27.
In some energy absorbers 23, testing suggests it would be
beneficial to include an aperture 60 at each of the four corners of
the lobes adjacent the base flange 27 (and extending onto the base
flange 27/strap 25). The lobes 24 are box-shaped with relatively
flat walls except at corners. Each lobe 24 includes top and bottom
walls 45, 46, and also vertical shear walls 47, 48 (which form ends
of the "box" in a longitudinal direction) and also include a front
wall 49 "closing" a front side of the box shape. The walls 45-48
are slightly crowned or curved for providing a softer impact (i.e.
less of a load spike prior to beginning to crush and collapse).
[0043] Some corners referred to extend top to bottom of the lobes
and are formed by material connecting adjacent walls 45-49 of the
lobes and the straps 25/base flange 27. These corners form radiused
structures extending at about a "90 degree" angle to a bumper beam
face (in an expected direction of impact), but include draft angles
to facilitate molding. The corners can provide significant
localized impact stiffness, adding to the inconsistency of impact
resistance against a pedestrian's leg along a length of the energy
absorber. By weakening these corners, such as by providing
apertures 60, 61 the high load spike that would occur from an
impact centered over a vertical shear wall is reduced to be more
consistent with other locations along the energy absorber. The
illustrated corners formed by joindure of any of the walls 45-49
and straps 25 and base flange 27 are typically about 2 mm-8 mm
radius, or more preferably about 3 mm-6 mm radius, and most
preferably about 3 mm-5 mm, although the present invention can be
used on narrower or greater radiused lobe wall structures.
[0044] It is contemplated that the energy absorber 23 can be
attached to the reinforcement beam 21 by different means. The
illustrated energy absorber 23 includes top and bottom attachment
flanges 28 spaced along a length of the energy absorber. The
illustrated bottom attachment flanges 28 include sets of three
adjacent bottom flanges 33-35 (FIG. 8), and the top attachment
flanges 28 include a single extra-wide opposing top flange 36. The
center bottom flange 34 and top flange 36 can include a tooth 37 or
pad 40, respectively, for frictionally engaging a mating feature
(or hole) in the top and bottom walls of the mating reinforcement
beam 21. The flanges 33-36 may also include exterior stiffener ribs
38,41 for added strength. The flanges 33-36 may include a friction
generating pad (instead of a tooth) for temporary retention to the
reinforcement beam (e.g. until a fascia is attached). The
illustrated top flange 36 includes an enlarged raised pad 40 and
also outside stiffener ribs 41. The tooth 37 and pad 40 are
configured with inclined lead-in surfaces that define a ramped
throat to facilitate attaching the energy absorber onto a bumper
reinforcement beam 21. It is contemplated that the energy absorber
23 could also (or instead) be configured for attachment to a RIM
fascia that covers the bumper system.
[0045] It is noted that FIGS. 2 and 6 illustrate the prior art
standardized test fixture 50 that simulates (i.e. "represents") a
pedestrian's leg (also called the "pedestrian's leg" or "pedestrian
leg impactor" herein). The leg 50 includes a steel rod 51 (i.e.
"bone"), foam 52 (i.e. "flesh"), and sleeve 53 (i.e. "skin"), as
noted above.
[0046] As shown in FIG. 14, the leg 50 may impact the energy
absorber 23 at different locations, illustrated as locations A, B,
or C in the figure, each being located in the pedestrian-impacting
bumper test area. At impact location A, the vertical shear walls X
and Y are engaged evenly, and at location C, the vertical shear
walls Y and Z are engaged evenly. As a center of the impact
location shifts from a center-of-lobe impact location "A" to an
edge-of-lobe impact location "C," there is a transition including
one position (see impact location B) aligned directly with one of
the vertical shear walls 47,48. It is noted that the preferred
crush lobe 24 has a centerline spacing (dimension DLS) of 110 mm.
This leads to a longitudinal spacing between vertical shear walls
47,48 in a given lobe in energy absorber 23 of about 65 mm-70 mm
(keeping in mind that draft angles for molding must be accounted
for, as well as radiused corners), while the longitudinal spacing
between vertical shear walls 47,48 of adjacent lobes is about 40
mm-45 mm. Considering the standardized leg impactor 50 has an outer
dimension of 132 mm, it is counter-intuitive that this spacing and
lobe width would provide a relatively constant impact resistance
across the entire pedestrian-impacting bumper test area. (See FIG.
6.) Thus, this is a surprising and unexpected result to us,
providing unexpected and unanticipated benefits.
[0047] FIG. 15 shows a force deflection curve (also called a "force
deflection profile") for a bumper system 20 like that shown in
FIGS. 4 and 6, where the energy absorber 23 included identical
lobes 24 across a pedestrian-impacting bumper test area "BTA", the
lobes 24 being centerline spaced at 110 mm longitudinally and
having straps of about 35 mm-40 mm width separating adjacent lobes.
The vertical shear walls 47,48, and also the top and bottom shear
walls 45,46, in the illustrated energy absorber 23 had a curvature
of about 150 mm-300 mm radius. The lobes 24 had a depth of 65 mm,
and a wall thickness of about 1.5 mm-2.5 mm, and included an
aperture 60 at each corner of the lobe adjacent the base flange,
and further included an aperture 61 centered on a tip of the
vertical shear walls 47,48 extending onto the front wall 49. The
lobes 24 did not include any ribs (66) nor undulations in the top
and bottom shear walls 47,48.
[0048] FIG. 15 is data from a test conducted at six impact
locations, each being located 11 mm apart from the previous impact
location. As shown in FIGS. 6 and 10, the first impact location A
was directed between the lobes in a center location (over a strap).
The next impact location B was directed 11 mm to one side, the next
impact location C was directed 11 mm still further toward one side,
and similarly for impact locations D, E, and F. The impact location
F was directed into a center of a lobe 24. Since all lobes 24 are
symmetrical and identical in size and shape, the impact locations
A-F represent the impact resistance for all locations across the
bumper test area, since the underlying structure of each lobe and
its relation to the impactor 50 is repeated as one continues across
a length of the energy absorber 23 in the bumper test area
dimension BTA. As shown in the graph of FIG. 13, the force of
resistance for all six locations A-F is virtually identical up to
25 mm intrusion, and is similar to within about +/-5% impact
resistance at 30 mm intrusion, and is still similar to within about
+/-10% impact resistance at about 60 mm intrusion. (Compare FIG. 15
which represents the test results on an energy absorber of the
present invention, to FIGS. 16-17 which represent two known/prior
art parts used as benchmarks, one being plastic, one being
metal.)
[0049] During an impact against a pedestrian's leg, a force
deflection curve (also called a force-deflection profile" or
"impact-force-versus-intrusion profile") results where the force of
resistance to the impact increases from zero, and then levels off,
and then again dramatically increases. Specifically, a first
portion of the force-deflection curve of an impact is greatly
influenced by deformation, flexure and compressing of the
pedestrian leg's flesh and skin (herein called "initial impact and
compression portion" of the force-deflection curve). This is
followed by a second portion (herein called the "working portion"
of the force-deflection curve during an impact crush stroke) where
the energy absorber is doing its work by the shear walls of crush
lobes crushing to absorb energy. (During this phase, the shear
walls "crinkle" and form multiple irregular bends and folds,
causing significant energy absorption via material deformation).
This is followed by a third portion (herein called the "stacked
flat portion" of the force-deflection curve, or in other words the
"reinforcement beam resistance portion") where the energy absorber
has basically crushed flat and thus the force of resistance is
primarily that of the underlying support structure (which in the
case of a bumper system is a reinforcement beam that is usually
metal and is very stiff). For example, in FIG. 15, the first
portion (i.e. "initial impact and compression portion" in the force
deflection curve) is from zero intrusion to about 30 mm intrusion;
the econd portion (i.e. the "working portion") is from 30 mm to
about 63 mm intrusion (with the force of resistance staying
relatively constant within a small range of variability), and the
third portion (i.e. the "beam resistance portion") is above 63 mm
intrusion (where the force of resistance increases dramatically).
Contrastingly, in FIG. 18, the first portion (i.e. "initial impact
and compression portion") is from zero to about 25 mm intrusion;
the second portion (i.e. the "working portion") is from 25 mm to
about 60 mm intrusion), and the third portion (i.e. the "beam
resistance portion") is above 60 mm intrusion. Contrastingly, in
FIG. 21, the first portion (i.e. "initial impact and compression
portion") is from zero to about 25 mm intrusion; the second portion
(i.e. the "working portion") is from 25 mm to about 70 mm
intrusion), and the third portion (i.e. the "beam resistance
portion") is above 70 mm intrusion.
[0050] We conducted several studies to determine a sensitivity of
energy absorber lobe dimensions and optimal ranges. Our studies
suggest that good ranges for a particular bumper system ("vehicle
application") as follows. It is noted that in our opinion, the
present dimensions are significant, unobvious, and provide
surprising and unexpected results since, for example, a 110 mm
spacing between lobe centerlines is unexpectedly different than any
dimension of the impactor 50 and unexpectedly different than any
dimension of a typical human leg. [0051] Lobe Width Spacing 90 mm
to 132 mm (more preferably 100 mm-120 mm, optimal 110 mm) [0052]
Lobe Height 60 mm +/-20% or more preferably +/-10% [0053] Depth 50
mm to 80 mm (influenced significantly by styling) [0054] Wall Crown
planar to crowned, or more preferably 150 mm and 300 mm [0055]
Thickness 1.5 mm to 2.25 mm +/-10% [0056]
Corrugations/stiffening-ribs along walls (as needed) [0057]
Radii/Holes along Corners and at Joints (vary as needed) [0058]
Strap widths 15 mm to 50 mm (vary as needed in combination with
holes, ribs)
[0059] It is contemplated that the present energy absorber 23 can
be made to mate with a linear reinforcement beam, or can be made to
mate with a longitudinally swept reinforcement beam (21) (see FIGS.
6 and 14). In the case of a swept beam, the lobes of the energy
absorber can be oriented to face parallel a direction of expected
impact, and/or oriented to face directly forwardly, and/or oriented
at slight angles to forwardly depending on their relation to a
corner of a vehicle, and depending on vehicle design. For example,
the lobes 24 could extend perpendicular to the adjacent portion of
the front face of the reinforcement beam (in which case, the end
lobes would potentially not extend parallel to the center lobes due
to a curved sweep of the beam), or the end lobes could be slightly
tilted inwardly at an angle (so that all the lobes extend parallel
and forwardly from the vehicle parallel a direction of travel of
the vehicle even though ends of the reinforcement beam are curved
rearwardly). Also, it is noted that the beam can be made of
different materials and formed by different processes, such a beam
that is roll formed of steel, or extruded of aluminum, or molded of
reinforced polymer.
[0060] The illustrated energy absorber is injection molded of
polymeric material adapted for absorbing energy, which materials
are well known and commercially available. The illustrated energy
absorber has enough longitudinal flexibility at its straps 25 to
flexibly wrap around and engage a face of a reinforcement beam,
even when the ends of the beam had a considerable sweep or an
increasing sweep (i.e. increasing rearward curvature near ends).
However, it is contemplated that a scope of the present innovation
includes energy absorbers made of steel or other metal, and that
the energy absorber can be longitudinally non-flexible and made to
nest against a particular beam face's profile).
[0061] FIGS. 18-20 are graphs showing force versus displacement
curves for bumper systems 20 of the present invention having an
identical reinforcement beam 21 and an energy absorber very similar
to the energy absorber 23. Specifically, the three energy absorbers
for FIGS. 18-20 each have identically shaped lobes and lobes
spacing (i.e. 110 mm at lobe centerline centers), but the walls
45-49 of the lobes in the energy absorbers of FIGS. 18-20 have
slightly different thicknesses and/or different apertures at
corners. Specifically, the lobes in each of FIGS. 18-20 were 60 mm
deep and each had a centerline spacing of lobes of 110 mm. (i.e.
The lobes were about 88 mm-90 mm at a base of the (side-located)
vertical shear walls, and the strap widths were about 20 mm-22 mm.)
A thickness of the shear walls 45-48 were changed between the
energy absorber of FIGS. 18-20 and apertures 60-61 were added at
corners of the shear walls 45-48 as needed to optimize uniformity
of impact resistive force at all longitudinal locations across the
beam impact area of the bumper systems.
[0062] The graphs of FIGS. 18-20 each show two impacts, one being
at a location on a lobe 24 aligned with a vertical shear wall 47
(or 48) such that a relatively higher impact resistance force is
expected, and one being centered over a lobe 24 where a relatively
lower impact resistance force is expected. The energy absorbers
tested in FIGS. 18-20 were each optimized to provide a consistent
impact resistance regardless of where a particular impact location,
by adjusting wall thickness and/or placement of apertures 60,61. As
illustrated, the force deflection curve for each of the energy
absorbers in FIGS. 18-20 are virtually identical up to an impact
stroke ("intrusion") of 30 mm. Notably, the energy absorbers of
FIGS. 18-20 also included walls adjusted for optimal wall
thickness, in order to cause a different level of impact resistance
force in the range between 30 mm intrusion to 65 mm. For example,
in FIG. 18, the desired force of resistance between 30 mm-65 mm
intrusion is 3 kN. Contrastingly, in FIG. 17, the desired force of
resistance between 30 mm-65 mm intrusion is 4 kN, and in FIG. 18,
the desired force of resistance between 30 mm-65 mm intrusion is 5
kN.
[0063] A similar test to that shown in FIGS. 18-20 was performed on
bumper systems with an energy absorber having a deeper lobe (24).
The results are shown in FIGS. 21-23 for an energy absorber having
a 70 mm depth lobe. FIGS. 24-26 show the results of a similar test
but using an energy absorber having an 80 mm depth lobe. The
results are believed to be self-explanatory, given the discussion
above. In each case, the impact resistance force was maintained
relatively close to the desired level of impact force resistance,
such as to within about +/-20% at 30 mm intrusion. It is noted that
consistency of impact resistance can be further improved by tuning
the energy absorbers using different "customized" apertures 60,61
as well as exterior ribs 62, as noted below.
[0064] In the following modified bumper systems and energy
absorbers, identical and similar components, features, and
characteristics are identified using the same numbers. Where there
is a significant change, the same identification number is used,
but a letter is added, such as "A," "B," "C," and etc. This is done
to reduce redundant discussion.
[0065] The energy absorbers shown in FIG. 27 (and test result shown
in FIG. 28) and FIG. 29 and FIG. 30 (and test result shown in FIG.
31) and FIG. 32 provide a further understanding of a scope of the
present invention. FIG. 27 (and the test result shown in the graph
of FIG. 28) shows that the present concept can embodied in an
energy absorber 23B without resorting to apertures and external
ribs. FIG. 29 shows an energy absorber 23C including only base
apertures 60 (and not apertures 61 at an outer corner on the face
of the lobes). FIG. 30 shows that the present concept can be
extended by tuning an energy absorber 23D using apertures 60,61 as
well as also using external ribs 62 (and FIG. 31 shows a graph of
data from same). In FIG. 30, the external ribs 62 form T-shaped
cross sections with adjacent portions of the associated (top or
bottom) walls.
[0066] FIG. 32 shows that the present concept can be used on
different beams and different support structures. For example, the
bumper reinforcement beam 21E in FIG. 31 is the same as that shown
in FIG. 13 but is used in a reversed orientation such that a center
channel 65 on the beam 21E faces forwardly (away from a vehicle) as
opposed to facing toward the vehicle. The energy absorber 23E
includes locater tabs 66 that extend into the channel 65 in the
beam 21E, such that the tabs 66 help to retain the energy absorber
23E on a face of the beam 21E during an impact.
[0067] Specifically, FIG. 27 illustrates a modified energy absorber
23B with lobe dimensions the same as those of energy absorber 23 in
FIG. 4, but characteristically the energy absorber 23B does not
have any corner apertures 60,61 for weakening corners, nor external
ribs 62 for stiffening the top and bottom shear walls 45,46. The
lobes 24B have a depth of 50 mm, and a longitudinal spacing of 100
mm. FIG. 28 is a force versus displacement curve for a bumper
system including the energy absorber 23B of FIG. 27. Notably, the
energy absorption is very consistent regardless of a location of
impact, as shown by the four impacts charted: one impact being
between adjacent lobes, one impact being on the edge of a lobe, one
impact being at a mid-center of a lobe, and another impact being on
a center of a lobe. Specifically, the impact resistive force is
very similar (within about +/-5% of an average number) up to a 30
mm intrusion, and further is similar (within about +1-10%) up to a
45 mm intrusion.
[0068] FIG. 29 shows an energy absorber 23C identical to that in
FIG. 27, but including base apertures 60. The illustrated energy
absorber 23C does not include apertures 61 at an outer corner on
the face of the lobes 24C.
[0069] FIG. 30 illustrates a modified energy absorber 23D with
dimensions as shown, but characteristically does have both corner
apertures 60 for weakening the corners and external ribs 62 for
stiffening the top and bottom walls 45, 46. The illustrated lobes
24D have a depth of 65 mm, and a longitudinal spacing of 100 mm.
FIG. 31 is a force versus displacement curve for a bumper system
including the energy absorber 23D of FIG. 30. Notably, the energy
absorption is very consistent regardless of a location of impact,
as shown by the four impacts charted: one impact being between
adjacent lobes, one impact being on the edge of a lobe, one impact
being at a mid-center of a lobe, and another impact being on a
center of a lobe. Specifically, the impact resistive force is very
similar (within about +/-5% of an average number) up to a 30 mm
intrusion, and further is similar (within about +/-10%) up to a 45
mm intrusion.
[0070] FIG. 31 shows a bumper system including a beam 21E and
energy absorber 23E similar to those shown in FIG. 13. However, the
beam 21E in FIG. 31, though the same as the beam 21 shown in FIG.
13, is used in a reversed orientation such that a center channel 65
on the beam 21E faces forwardly (away from a vehicle). (In FIG. 13,
the channel faced inwardly toward the vehicle.) The energy absorber
23E in FIG. 31 includes locater tabs 66 that extend into the
channel 65 in the beam 21E to retain the energy absorber 23E on a
face of the beam 21E during an impact.
[0071] The illustrated energy absorbers are injection molded from
polymer, but it is specifically contemplated that energy absorbers
can be made of other materials (such as deformable steel, other
metal and non-metal materials), and made by other methods of
manufacture (such as thermoforming, compression molding, stamping)
and still be within a scope of the present invention. It is
contemplated that the present innovation can be used in locations
on a vehicle other than just on vehicle bumpers, inside and/or
outside the vehicle, such as for door side impact, A-pillar impact,
and under-the-dash impacts, and still be within a scope of the
present invention.
[0072] It is to be understood that variations and modification can
be made on the aforementioned structure without departing from the
concepts of the present invention, and further it is to be
understood that such concepts are intended to be covered by the
following claims unless these claims by their language expressly
state otherwise.
* * * * *