U.S. patent application number 09/848204 was filed with the patent office on 2001-09-06 for automotive impact energy absorbing structure.
This patent application is currently assigned to TOYOTA JIDOSHA KABUSHIKI KAISHA. Invention is credited to Takahara, Isamu.
Application Number | 20010019214 09/848204 |
Document ID | / |
Family ID | 27324281 |
Filed Date | 2001-09-06 |
United States Patent
Application |
20010019214 |
Kind Code |
A1 |
Takahara, Isamu |
September 6, 2001 |
Automotive impact energy absorbing structure
Abstract
An automotive impact energy absorbing structure has a structural
member having an inner panel, and an interior member spaced from
the inner panel by an interval extending therefrom toward the
inside of a compartment. A hollow body is disposed within the
interval. Impact energy applied to the hollow body from inside the
compartment is absorbed by deformation of the hollow body.
Inventors: |
Takahara, Isamu; (Nagoya,
JP) |
Correspondence
Address: |
OLIFF & BERRIDGE, PLC
P.O. Box 19928
Alexandria
VA
22320
US
|
Assignee: |
TOYOTA JIDOSHA KABUSHIKI
KAISHA
|
Family ID: |
27324281 |
Appl. No.: |
09/848204 |
Filed: |
May 4, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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09848204 |
May 4, 2001 |
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09069734 |
Apr 30, 1998 |
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6254172 |
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Current U.S.
Class: |
296/187.05 ;
296/203.02 |
Current CPC
Class: |
B60R 21/04 20130101;
B60R 2021/0435 20130101 |
Class at
Publication: |
296/189 ;
296/203.02 |
International
Class: |
B62D 025/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 18, 1997 |
JP |
HEI 9-176594 |
Jun 18, 1997 |
JP |
HEI 9-176590 |
Jun 19, 1997 |
JP |
HEI 9-177775 |
Claims
What is claimed is:
1. An automotive impact energy absorbing structure comprising: a
structural member extending in an upper portion of a vehicle body
in a front-and-rear direction relative to the vehicle body, the
structural member including a first panel; an interior member
spaced from the first panel by an interval extending from the first
panel toward an inside of a compartment of the vehicle body, the
interior member being formed so that a thickness of the interior
member in a section taken on a plane perpendicular to the
front-and-rear direction varies; and a hollow body made from metal
disposed in the interval and fixed to the interior member.
2. The automotive impact energy absorbing structure according to
claim 1, wherein the structural member further includes two
flange-connected portions whereby the first panel and a second
panel spaced from the first panel are connected, the hollow body is
disposed near one flange-connected portion of the two
flange-connected portions, and the interior member is formed so
that a portion of the interior member remote from the one
flange-connected portion is thinner than other portions of the
interior member.
3. The automotive impact energy absorbing structure according to
claim 1, wherein the interior member is formed so that two end
portions of the interior member in the section are thickest and a
portion of the interior member remote from the end portions is
thinnest.
4. The automotive impact energy absorbing structure according to
claim 1, wherein the interior member has two end portions in the
section and portions that become thinner from the end portions to
one portion of the interior member.
5. The automotive impact energy absorbing structure according to
claim 1, wherein the hollow body defines a lengthwise direction
with an axis and has an angular sectional shape in a section taken
on a plane perpendicular to the axis, the angular sectional shape
being formed by an outward wall portion extending substantially
along an inward side wall of the inner panel, an inward wall
portion extending substantially along an outward side surface of
the interior member, a first side wall portion and a second side
wall portion, the first side wall portion and the second side wall
portion connecting the outward wall portion to the inward wall
portion.
6. The automotive impact energy absorbing structure according to
claim 5, wherein the hollow body is fixed to the interior member,
and wherein the outward wall portion of the hollow body has a
contact portion that contacts the inner panel and a non-contact
portion spaced from the inner panel.
7. The automotive impact energy absorbing structure according to
claim 1, wherein the hollow body is adhered to the interior member
by an adhesive.
Description
INCORPORATION BY REFERENCE
[0001] The disclosures of Japanese Patent Application Nos. Hei
9-176594 filed on Jun. 18, 1997, Hei 9-176590 filed on Jun. 18,
1997, and Hei 9-177775 filed on Jun. 19, 1997, each including the
specification, drawings and abstract, are incorporated herein by
reference in their entirety.
BACKGROUND OF THE INVENTION
[0002] 1. Field of Invention
[0003] The present invention relates to an automotive impact energy
absorbing structure and, more particularly, to an impact energy
absorbing structure for absorbing impact energy applied to an upper
portion of a body of a motor vehicle from inside a compartment,
using an energy absorbing member that deforms to absorb the impact
energy applied thereto.
[0004]
[0005] 2. Description of Related Art
[0006] Japanese patent application laid-open Nos. Hei 8-119047 and
Hei 8-127298 propose automotive energy absorbing structures for
absorbing impact energy using a resin-made energy absorbing body
(for example, a grating-like rib) that is disposed in a space
between a pillar having an inner panel and a pillar garnish
disposed at a passenger compartment interior side and separated
from the inner panel by the space.
[0007] If the energy absorbing body is formed as a resin-made
grating-like rib member, the amount of energy absorbed by the
member during an initial period of application of impact energy is
relatively small since plastic deformation of the resin-made
grating-like rib member starts late relative to the amount of
deformation. Furthermore, the resin-made grating-like rib member is
subject to changes in load bearing strength due to temperature or
humidity changes and, in some environments, tends to deteriorate
over time, thus resulting in a decreased capacity for energy
absorption. Therefore, in designing energy absorbing resin-made
grating-like rib members, the dimensions thereof are determined so
that the members remain able to absorb desired amounts of energy
even when they deteriorate. Thus, the energy-absorbing members
inevitably become large in size.
SUMMARY OF THE INVENTION
[0008] Accordingly, it is an object of the present invention to
provide an automotive impact energy absorbing structure in which
the time until the start of plastic deformation relative to the
amount of deformation during an initial period of application of
impact energy is shortened while retaining an intended energy
absorption capacity, and which allows a size reduction of an energy
absorbing member.
[0009] It is another object of the invention to provide an
automotive impact energy absorbing structure that allows adjustment
of an energy absorbing characteristic.
[0010] It is still another object of the invention to provide an
automotive impact energy absorbing structure that allows the
deforming direction of the energy absorbing structure to be
forcibly determined by an interior member disposed at a compartment
interior side of the energy absorbing member.
[0011] According to a first aspect of the invention, there is
provided an automotive impact energy absorbing structure including
a structural member provided in an upper part of a vehicular body.
The structure member has an inner panel. An interior member is
spaced from the inner panel by an interval extending therefrom
toward the inside of a compartment. A hollow body made from metal
is disposed in the interval.
[0012] According to a second aspect of the invention, there is
provided an automotive impact energy absorbing structure including
a structural member extending in an upper portion of a vehicle
body, in a lengthwise direction, and an interior member spaced from
the structure member by an interval extending therefrom toward an
inside of a compartment. A hollow body made from metal is disposed
in the interval. The hollow body is adhered to the interior member
so that an axis of the hollow body extends in a lengthwise
direction relative to the structural member.
[0013] According to a third aspect of the invention, there is
provided an automotive impact energy absorbing structure including
a structural member extending in an upper portion of a vehicle body
in a front-and-rear direction relative to the vehicle body. The
structural member includes a panel. An interior member is spaced
from the panel by an interval extending therefrom toward an inside
of a compartment. The interior member is formed so that the
thickness of the interior member in a section taken on a plane
perpendicular to an axis extending in a lengthwise direction
relative to the structural member varies locally. A hollow body
made from metal is disposed in the interval and fixed to the
interior member.
[0014] According to the first aspect of the invention, if a load
equal to or greater than a predetermined value is applied to the
hollow body, the hollow body deforms, thereby absorbing impact
energy.
[0015] According to the first aspect of the invention, the hollow
body has a greater ductility than a grating rib, and starts to
plastically deform at an earlier timing relative to an amount of
displacement. Therefore, the hollow body can sufficiently absorb
impact energy during an initial period of load application.
Furthermore, the hollow body may have a closed configuration in a
section taken on a plane perpendicular to the axis of the hollow
body. Then, it becomes easier to adjust the size of the area that
receives load or the size of the area that transmits load imposed
on the hollow body to the inner panel.
[0016] The hollow body may also be formed by extrusion forming, and
can easily be formed into a desired configuration or desired
dimensions. Therefore, it becomes possible to reduce changes in the
energy absorbing characteristics depending on the direction of load
application by forming an entire configuration of the hollow body
that is optimal in accordance with the interval between the
structure member and the inner panel, by locally changing the
thickness of the hollow body, or by forming a rib standing in the
hollow of the hollow body.
[0017] Since the hollow body is not substantially affected by
atmosphere temperature or humidity, there is only a small change in
load bearing strength due to temperature or humidity and
substantially no deterioration over time due to the environment. If
the hollow body is formed from aluminum by extrusion forming, it is
possible to re-process or reshape a hollow body deformed for
absorption of impact energy, for reuse, since aluminum is suitable
for recycling or reuse.
[0018] According to the second aspect of the invention, the
interior member and the hollow body have different ductilities.
Therefore, if a load equal to or greater than a predetermined value
is transmitted to the hollow body by the interior member, a
relative displacement occurs at adhering portions between the two
members so that the sheering force based on the relative
displacement acts on the adhesive. The reaction force to the
sheering force at the adhering portions between the interior member
and the hollow body also absorbs impact energy, thereby achieving
energy absorbing characteristics different from the original energy
absorbing characteristics of the hollow body. Furthermore, a change
in the adhering manner can also change the energy absorbing
characteristics.
[0019] Since the hollow body can be formed into any desired
sectional shape, the hollow body can easily be adapted to the
interval between the structure member and the interior member.
Furthermore, because it is possible to select a location of
adhesion to the interior member and an adhesion area from a wide
range of choices, and because it is possible to achieve various
characteristics by selecting a wall thickness or a sectional shape
of the hollow body, the degree of freedom in selecting energy
absorbing characteristics is high.
[0020] The interior member may be attached to the structural member
as follows. First, an adhesive is applied to required portions of
the interior member, and then the hollow body is adhered to the
interior member by the adhesive. Alternatively, after the hollow
body is placed on a required location on the interior member, an
adhesive is applied to adhere the hollow body to the interior
member. After that, the interior member, together with the hollow
body, can easily be attached to the structural member.
[0021] According to the third aspect of the invention, if a load
equal to or greater than a predetermined value is applied so that
the interior member deforms, the hollow body fixed to the interior
member is displaced together with the interior member in the
direction of the load. When the hollow body contacts the panel of
the structure member, the hollow body starts to plastically deform,
absorbing impact energy.
[0022] According to the third aspect of the invention, the
thickness of the interior member locally varies. If a load is
applied to a portion of the interior member that is remote from the
thinnest portion of the interior member, the interior member
deforms with the thinnest portion acting like a fulcrum. As the
interior member thus deforms, the hollow body is displaced toward
the panel of the structure member. Therefore, it is possible to
forcibly restrict a portion of the hollow body that deforms, by
using the interior member. If a load is applied to the thinnest
portion of the interior member, the entire interior member is
displaced in the direction of the load, thereby deforming the
hollow body. Therefore, it is easy to provide an energy absorbing
body with an amount of displacement, a shape and the like which are
required for energy absorption. Thereby, a sufficient amount of
energy absorption can be secured. Furthermore, since there is no
need to provide a hollow body with deforming characteristics in
accordance with various load directions in order to secure a
required amount of energy absorption, the configuration and
structure of the energy absorbing body can be simplified.
BRIEF DESCRIPTION OF THE DRAWINGS
[0023] The foregoing and further objects, features and advantages
of the present invention will be described in or apparent from the
following description of preferred embodiments with reference to
the accompanying drawings, wherein like numerals are used to
represent like elements and wherein:
[0024] FIG. 1 is a sectional view of a first preferred embodiment
of the automotive impact energy absorbing structure taken on line
1-1 of FIG. 3;
[0025] FIG. 2 is a sectional view of the first preferred embodiment
of the automotive impact energy absorbing structure taken on line
2-2 of FIG. 3;
[0026] FIG. 3 is a perspective view of an interior member and a
hollow body in the first embodiment of the invention viewed from
outside the compartment;
[0027] FIG. 4 is a sectional view of a second embodiment of the
automotive impact energy absorbing structure of the invention taken
on an imaginary plane perpendicular to a lengthwise axis of a
structural member,
[0028] FIG. 5 is a sectional view of a third embodiment of the
automotive impact energy absorbing structure of the invention taken
on an imaginary plane perpendicular to a lengthwise axis of a
structural member,
[0029] FIG. 6 is a perspective view of a hollow body in the third
embodiment of the invention viewed from outside the
compartment;
[0030] FIG. 7 is a sectional view of a fourth embodiment of the
automotive impact energy absorbing structure of the invention taken
on an imaginary plane along a lengthwise axis of a structural
member,
[0031] FIG. 8 is a sectional view of the fourth embodiment of the
automotive impact energy absorbing structure of the invention taken
on an imaginary plane perpendicular to the lengthwise axis of the
structural member,
[0032] FIG. 9 is a sectional view of a fifth embodiment of the
automotive impact energy absorbing structure of the invention taken
on an imaginary plane perpendicular to a lengthwise axis of a
structural member,
[0033] FIG. 10 is a sectional view of a sixth embodiment of the
automotive impact energy absorbing structure of the invention taken
on an imaginary vertical plane that perpendicular to a center axis
extending in a front-to-rear direction relative to a vehicular
body,
[0034] FIG. 11 is a sectional view of a seventh embodiment of the
automotive impact energy absorbing structure of the invention taken
on an imaginary vertical plane that includes a center axis
extending in a front-to-rear direction relative to a vehicular
body,
[0035] FIG. 12 shows an impact energy absorbing characteristic
curve indicating the relationship between acceleration and time
regarding the first and second embodiments,;
[0036] FIG. 13 shows an impact energy absorbing characteristic
curve indicating the relationship among acceleration, load and
displacement regarding the first embodiment;
[0037] FIG. 14 shows an impact energy absorbing characteristic
curve indicating the relationship between acceleration and time
regarding a comparative example;
[0038] FIG. 15 shows an impact energy absorbing characteristic
curve indicating the relationship among acceleration, load and
displacement regarding a comparative example;
[0039] FIG. 16 shows impact energy absorbing characteristic curves
indicating the relationship between load and displacement regarding
the fourth embodiment of the invention;
[0040] FIG. 17 shows impact energy absorbing characteristic curves
indicating the relationship between load and displacement regarding
the fourth embodiment and a comparative example;
[0041] FIG. 18 is a sectional view of an eighth embodiment of the
automotive impact energy absorbing structure of the invention,
taken on an imaginary plane perpendicular to a lengthwise axis of a
structure member,
[0042] FIG. 19 is another sectional view of the eighth embodiment
of the automotive impact energy absorbing structure of the
invention, taken on a different imaginary plane perpendicular to a
lengthwise axis of a structure member,
[0043] FIG. 20 is a sectional view of a ninth embodiment of the
automotive impact energy absorbing structure of the invention,
taken on an imaginary plane perpendicular to a lengthwise axis of a
structure member,
[0044] FIG. 21 is a sectional view of a tenth embodiment of the
automotive impact energy absorbing structure of the invention,
taken on an imaginary plane perpendicular to a lengthwise axis of a
structure member,
[0045] FIG. 22 is a perspective view of an interior member and a
hollow body in the eight, ninth and tenth embodiments, viewed from
outside a compartment;
[0046] FIG. 23 shows impact energy absorbing characteristic curves
indicating the relationship between load and displacement regarding
the eight embodiment and a comparative example;
[0047] FIG. 24 shows impact energy absorbing characteristic curves
indicating the relationship between load and displacement regarding
the ninth and tenth embodiments;
[0048] FIG. 25 shows an impact energy absorbing characteristic
curve indicating the relationship between load and displacement
regarding a modification according to the invention;
[0049] FIG. 26 is a sectional view of an eleventh embodiment of the
automotive impact energy absorbing structure of the invention,
taken on an imaginary plane perpendicular to a lengthwise axis;
[0050] FIG. 27 is another sectional view of the eleventh
embodiment, taken on a different imaginary plane perpendicular to a
lengthwise axis, the imaginary plane being different from the plane
used in FIG. 26;
[0051] FIG. 28 is still another sectional view of the eleventh
embodiment, taken on a different imaginary plane perpendicular to a
lengthwise axis, the imaginary plane being different from the
planes used in FIGS. 26 and 27;
[0052] FIG. 29 shows an impact energy absorbing characteristic
curve indicating the relationship between load and displacement
regarding the eleventh embodiment;
[0053] FIG. 30 shows another impact energy absorbing characteristic
curve indicating the relationship between load and displacement
regarding the eleventh embodiment; and
[0054] FIG. 31 shows still another impact energy absorbing
characteristic curve indicating the relationship between load and
displacement regarding the eleventh embodiment.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
[0055] Preferred embodiments of the present invention will be
described in detail hereinafter with reference to the accompanying
drawings.
[0056] A first embodiment of the automotive impact energy absorbing
structure of the invention will be described with reference to the
sectional views of FIGS. 1 and 2 and the perspective view of FIG. 3
showing an interior member viewed from outside a vehicular body. In
an automotive impact energy absorbing structure according to the
first embodiment, impact energy applied from a compartment interior
is absorbed in an upper portion of the vehicle body provided with a
structural member 20 and an interior member 22. The automotive
impact energy absorbing structure includes a hollow body 24 for
absorbing energy.
[0057] The structural member 20 in the first embodiment shown in
FIGS. 1, 2 and 3 is, for example, a steel-made front pillar
extending generally in a top-to-bottom direction relative to the
vehicle body. The structural member 20 is formed of an inner panel
26 and an outer panel 28 spaced from the inner panel 26, toward the
outside of the compartment. Furthermore, a reinforcing panel 30 is
disposed between and spaced from the inner panel 26 and the outer
panel 28. The structural member 20 has two flange-connected
portions 32, 33 at which two flanges of the inner panel 26 and two
corresponding flanges of the outer panel 28 are placed over and
spot-welded to two corresponding flanges of the reinforcing panel
30. The structural member 20 has a closed configuration in a
section taken on an imaginary plane perpendicular to a lengthwise
axis of the structural member 20.
[0058] The interior member 22 is, for example, a pillar garnish
formed from a hard resin, such as acrylonitrile butadiene styrene
(ABS) or polypropylene (PP). The interior member 22 is spaced from
the inner panel 26 of the structural member 20, in a direction
R.sub.1 toward the inside of the compartment, by an interval 36
needed for energy absorption. The interior member 22 extends along
the length of the inner panel 26. The interval 36 varies in size
depending at locations in the section, but may, for example, be
determined within the range of 5 to 40 mm.
[0059] The hollow body 24 is disposed within the interval 36. The
hollow body 24 is, for example, formed from aluminum by extrusion.
Aluminum alloys, titanium, titanium alloys, magnesium or magnesium
alloys may instead be used to form the hollow body 24. However,
aluminum is preferred because it is relatively easy to form and is
recyclable. In the first embodiment, as shown in FIGS. 1 through 3,
the hollow body 24 is positioned near the flange-connected portion
33. In a case where the structural member 20 is used as a front
pillar, a front windshield pane 38 is disposed near the other
flange-connected portion 32. Loads imposed on the impact energy
absorbing structure of the invention by an occupant will not be
applied to the structural member at the flange-connected portion
32. Therefore, there is no need to dispose a hollow body in a
portion of the interval 36 that is near the flange-connected
portion 32. A opening trim 39 is attached to the flange-connected
portion 33 to maintain the air-tightness of a door (not shown).
[0060] In the first embodiment, as shown in FIG. 1, the hollow body
24 has a generally angular shape in a section taken on a plane
perpendicular to the lengthwise axis of the hollow body 24. The
generally angular sectional shape is formed by an outward wall
portion 40 extending substantially along an inward surface 27 of
the inner panel 26, an inward wall portion 41 extending
substantially along an outward surface of the interior member 22,
and two side wall portions 42, 43 connecting the outward wall
portion 40 and the inward wall portion 41.
[0061] The hollow body 24 is fixed to the interior member 22 by,
for example, inserting a plurality of fitting protrusions 48
protruding from the interior member 22 toward the outside of the
compartment into corresponding holes in the hollow body 24, and
then thermally riveting the fitting protrusions 48. An adhesive may
instead be used to fix the hollow body 24 to the interior member
22.
[0062] The interior member 22 has two fitting seats 50 as shown in
FIG. 3. Known resin-made clips (not shown) are fitted to the
fitting seats 50, and then inserted into corresponding holes in the
inner panel 26. The interior member 22 is thus attached to the
inner panel 26.
[0063] Preferably, the hollow body 24 extends substantially over
the entire length of the interior member 22. In the first
embodiment, as shown in FIG. 3, the hollow body 24 substantially
overlaps the fitting seats 50 in the direction of the length of the
interior member 22, so that the hollow body 24 is formed of two
sections separated by one of the fitting seats 50 that is provided
in a central portion of the interior member 22. However, it is
possible to use a single-body hollow body if the positions of the
fitting seats are changed.
[0064] In the first embodiment, as shown in FIGS. 1 and 2, the
outward wall portion 40 of the hollow body 24 has a contact portion
44 that contacts the inner panel 26, and a non-contact portion 45
spaced from the inner panel 26. The contact portion 44 of the
outward wall portion 40 of the hollow body 24 contacting the inner
panel 26 is near the flange-connected portion 33, and the
non-contact portion 45 of the outward wall portion 40 is relatively
remote from the flange-connected portion 33. The lengths a.sub.1,
a.sub.2 of the contact portion 44 and the intervals b.sub.1,
b.sub.2 between the non-contact portion 45 and the inner panel 26
vary depending on sections taken on planes perpendicular to an axis
in the lengthwise direction of the structural member 20 as
indicated in FIGS. 1 and 2. Such dimensional variations are largely
based on the variation of the sectional shape of the structural
member 20, for example, a front pillar, along the length
thereof.
[0065] The hollow body 24 may be formed such that the wall
thickness in a section taken on a plane perpendicular to an axis in
the lengthwise direction of the structural member 20 varies locally
in a peripheral direction. In the first embodiment, as shown in
FIGS. 1 and 2, the contact portion 44 of the outward wall portion
40 of the hollow body 24 and a portion 46 of the inward wall
portion 41 of the hollow body 24 substantially facing the contact
portion 44 are thicker than the other wall portions of the hollow
body 24. The thickness of the side wall portions 42, 43 is equal to
the thickness of angled portions 47, and is the thinnest. For
example, the greatest thickness of the inward wall portion 41 may
be about 3 mm, and the greatest thickness of the outward wall
portion 40 may be about 2 mm, and the thickness of the two side
wall portions 42, 43 may be about 1 mm.
[0066] A side wall portion 43, that is, one of the two side wall
portions 42, 43 closer to the flange-connected portion 33, is
inclined to a direction of a load f.sub.1 that is expected to be
applied from an occupant 52. More specifically, the side wall
portion 43 is inclined so that when the load f.sub.1 is applied,
the side wall portion 43 can fall or bend away from the
flange-connected portion 33. Although no particular structure is
provided in the hollow of the hollow body 24 in the first
embodiment, it is also possible to provide a rib 54 and/or a rib 55
inside the hollow body 24 as indicated by broken lines in FIG. 1.
The rib 55 extends in the direction of the load f.sub.1, whereas
the rib 54 extends in a different direction of a load f.sub.2 that
is also expected to be applied from the occupant 52.
[0067] In the first embodiment of the invention, the hollow body 24
deforms to absorb impact energy if at least a predetermined load is
applied to the hollow body 24 by way of the interior member 22.
[0068] Since the hollow body 24 has a greater ductility than
resin-made grating ribs, the hollow body 24 starts to plastically
deform sooner relative to the amount of displacement than the
conventional resin-made grating ribs. Therefore, the hollow body 24
can sufficiently absorb impact energy during an initial period of
reception of a load. Furthermore, since the hollow body 24 has a
closed configuration in a section taken on a plane perpendicular to
the lengthwise axis of the hollow body 24, it is easy to adjust the
extent of the area that receives load and the extent of the area
that transmits load from the hollow body 24 to the inner panel
26.
[0069] The configuration and the dimensions of the hollow body 24
can be freely determined through extrusion forming. Therefore, it
is possible to reduce the changes in energy absorbing
characteristics depending on the direction of load application, by
forming an optimal configuration of the entire hollow body 24 in
accordance with the interval 36 between the inner panel 26 of the
structural member 20 and the interior member 22, by locally varying
the thickness of the hollow body 24 or by providing the ribs 52, 55
in the hollow of the hollow body 24.
[0070] The hollow body 24 is not substantially affected by
atmospheric temperature or humidity. That is, the changes in the
load bearing strength of the hollow body 24 depending on
temperature or humidity are small, and the hollow body 24 does not
undergo substantial deterioration over time due to the environment
of use. Therefore, the hollow body 24 can retain intended impact
energy absorbing characteristics.
[0071] If the hollow body 24 is formed from aluminum by extrusion,
it is possible to re-process or reshape a deformed hollow body 24
for reuse since aluminum is suitable for recycling or reuse. The
hollow body 24 can be made from materials other than metal, so long
as the selected material plastically deforms sooner as compared,
e.g., to conventional resin-made grating ribs, while at the same
time maintains a predetermined impact energy absorbing capacity
against the impact energy created by the impact.
[0072] Furthermore, the hollow body 24 has an angular shape. The
inward wall portion 41 serves as a load-receiving area, and the
outward wall portion 40 serves as an area through which the load
transmitted to the hollow body 24 is transmitted to the inner panel
26. The two side wall portions 42, 43 maintain load. Since the
angled portions 47 of the hollow body 24 are deformed to displace
the hollow body 24 upon receiving a load, the maximum deformation
displacement of the hollow body 24 can be increased.
[0073] If a load is applied to the hollow body 24 in a direction
substantially perpendicular to the contact portion 44, the hollow
body 24 undergoes deformation during which the non-contact portion
45 is displaced so as to contact the inner panel 26, with the
contact portion 44 being the movement pivot. Therefore, a
deformation displacement greater than the interval between the
inner panel 26 and the interior member 22 can be secured, such that
sufficient impact energy absorption can be achieved even if the
interval is relatively small.
[0074] If a load is applied to the hollow body 24 in a direction
substantially perpendicular to the non-contact portion 45, the
hollow body 24 deforms without being substantially displaced,
thereby absorbing impact energy.
[0075] If a load is applied to the hollow body 24 in a direction
substantially perpendicular to the contact portion 44, the load
acts on the hollow body 24 at a position relatively close to the
flange-connected portion 33. The hollow body 24 thereby deforms
and, simultaneously, the non-contact portion 45 is displaced so as
to contact the inner panel 26, with the contact portion 44 being
the movement pivot. Since the non-contact portion 45 is remote from
the flange-connected portion 33, the hollow body 24 becomes
displaced away from the flange-connected portion 33. The
flange-connected portion 33 has a great rigidity, so that the
flange-connected portion 33 of the structural member 20 produces a
great reaction force to a load thereon. However, since the hollow
body 24 is displaced away from the flange-connected portion 33, the
influence of a reaction force from the flange-connected portion 33
is substantially avoided.
[0076] The hollow body 24 having different wall thicknesses in
different positions in a peripheral direction can easily be
produced by extrusion forming of a hollow body. Thereby it is
possible to properly determine the magnitude of an initial load,
the magnitude of load to be maintained, the extend of displacement
of the hollow body 24, and so on.
[0077] If a load is applied to the hollow body 24 in a direction
substantially perpendicular to the contact portion 44, a thick wall
portion of the inward wall portion 41 receives the load so that
deformation of the inward wall portion 41 in the direction of the
load can be prevented during an initial period of the load
application. Furthermore, since the contact portion 44 of the
outward wall portion 40 has a relatively great thickness,
deformation of the outward wall portion 40 in the direction of the
load can also be prevented during an initial period. Because the
inward wall portion 41 and the outward wall portion 40 are thus
prevented from being deformed, and because the thin angled portions
47 of the inward wall portion 41 and the outward wall portion 40
become more likely to deform, application of a load to the hollow
body 24 in a direction substantially perpendicular to the contact
portion 44 causes the two side wall portions 42, 43 of the hollow
body 24 to fall or bend so that the entire hollow body 24 is
displaced in a direction perpendicular to the direction of the
load. Furthermore, the hollow body 24 is displaced, with the
contact portion 44 being the movement pivot, so that a great
deformation displacement can be secured, and so that influence of a
reaction force from the flange-connected portion 33 can be more
effectively avoided. If a load is applied to the hollow body 24 in
a direction substantially perpendicular to the non-contact portion
45, the inward wall portion 41 and the two side wall portions 42,
43 deform without a substantial displacement of the hollow body 24,
thereby absorbing impact energy.
[0078] In a second embodiment of the invention as shown in FIG. 4,
a hollow body 64 differs from the hollow body 24 shown in FIGS. 1
through 3. The hollow body 64, made, for example, from aluminum,
has an outward wall portion 66, an inward wall portion 67 and two
side wall portions 68, 69. The wall thickness of the hollow body 64
in a section taken on a plane perpendicular to an axis in the
lengthwise direction of the structural member 20 varies locally.
The outward wall portion 66 is shaped so that an intermediate
portion thereof in a section taken on a plane perpendicular to an
axis in the lengthwise direction of the structural member 20 is
spaced from an inner panel 26 and other portions of the outward
wall portion 66 are in contact with the inner panel 26. The hollow
body 64 further has notches 70 that are formed in angled portions
between the outward wall portion 66 and the side wall portions 68,
69. Upon receiving a load, the notches 70 induce the side wall
portions 68, 69 to fall or bend in and maintain a substantially
constant bending load during the process of the bending deformation
of the side wall portions 68, 69.
[0079] In a third embodiment as shown in FIGS. 5 and 6, a hollow
body 24 may be attached to an inner panel 26 using a fasting device
72. The hollow body 24 has a through hole 74 that is formed in an
outward wall portion 40 for inserting the fastening device 72, and
another hole 76 formed in an inward wall portion 41. The hole 74 of
the outward wall portion 40 is defined by a positioning portion 78
for holding the hollow body 24 at a predetermined position, and by
a deforming portion 79 for displacement of the hollow body 24
relative to the fastening device 72. The fastening device 72 shown
in FIGS. 5 and 6 is, as an example, a tapping screw.
[0080] The hollow body 24 is fixed to the inner panel 26 by
inserting the fastening device 72 through the hole 76 and into the
positioning portion 78 of the hole 74, and then screwing the
fastening device 72 into a grommet member 80 fixed to an inner
panel 26. When a load f.sub.1 is applied, the deforming portion 79
of the hole 74 of the hollow body 24 deforms allowing the hollow
body 24 to shift relative to the fastening device 72 so that the
hollow body 24 moves away from flange-connected portion 33.
[0081] If the fastening device 72 is disposed at a suitable
position and a load is applied to the hollow body 24 in a certain
direction, the load displaces the hollow body 24 while deforming
the deforming portion 79. An increased deformation displacement can
thus be achieved. Furthermore, deformation of the deforming portion
79 absorbs impact energy.
[0082] In a fourth embodiment as shown in FIGS. 7 and 8, an inner
panel 86 has a plurality of support portions 88 that contact a
hollow body 84 made from, for example, aluminum. The support
portions 88 are raised in the form of protuberances in a direction
R.sub.1 to the inside of a compartment. The support portions 88 are
arranged in the direction of the length of the inner panel 86 and
spaced by intervals L. In the fourth embodiment as shown in FIGS. 7
and 8, the support portions 88 of the inner panel 86 are sloped so
that when a load f.sub.1 equal to or greater than a predetermined
value is applied, the hollow body 84 can shift in a direction away
from the flange-connected portion 33. More specifically, the
support portions 88 are raised by drawing them from a surface 89 of
the inner panel 86 in such a manner that the height of the slope
surface of each support portion 88 increases as the distance to the
flange-connected portion 33 decreases.
[0083] When a load equal to or greater than the predetermined value
is applied, the hollow body 84 undergoes elastic and plastic
deformation .delta. as indicated by a broken line in FIG. 7, and
then further deforms plastically. Since the support portions 88 are
sloped in the fourth embodiment, the hollow body 84, upon receiving
a load, is displaced sliding on the support portions 88 and,
therefore, shifting away from the flange-connected portion 33. The
outward wall portion 90 of the hollow body 84 is formed such that a
portion of the outward wall portion 90 that is relatively close to
the flange-connected portion 33 contacts the support portions 88 of
the inner panel 86.
[0084] The hollow body 84 has, in the direction of the length of
the structural member 20, portions that contact the support
portions 88 of the inner panel 86 and portions that are apart from
the inner panel 86. Therefore, when a load is applied to the entire
hollow body 84, the portions apart from the inner panel 86 bend,
with the support portions 88 acting as fulcrums, thus deforming
elastically and plastically. This deformation absorbs impact
energy. After that, the hollow body 84 is squeezed while continuing
to plastically deform, thereby absorbing impact energy. The
combination of elastic deformation and plastic deformation of the
hollow body 84 occurring during the bending of the hollow body 84
adds to the initial deformation load. The magnitude of the initial
deformation load can be varied by adjusting the intervals between
the support portions 88.
[0085] When a load is applied to the hollow body 84, portions of
the hollow body 84 between the support portions 88 of the inner
panel 86 elastically deform and, simultaneously, the hollow body 84
shifts in such a direction as to move away from the
flange-connected portion 33. In this embodiment, since the hollow
body 84 is supported only by the support portions 88, the load
applied to the individual support portions 88 is greater than the
load that would be applied if the entire hollow body 84 is
supported by full surface contact. The friction on the support
portions 88 is thus increased. However, because the support
portions 88 receive greater loads, the transition from a static
friction to a dynamic friction state, that is, the arrival at a
threshold load at which the hollow body 84 starts to slide occurs
sooner. Thus, the hollow body 84 starts to slide earlier, thereby
increasing the entire deformation displacement.
[0086] In a fifth embodiment as shown in FIG. 9, a structural
member 100 is, for example, a center pillar extending substantially
in a top-and-bottom direction relative to a vehicle body. The
structural member 100 includes an inner panel 102 and an outer
panel 104. The structural member 100 has two flange-connected
portions 106, 107 at which flanges of the inner panel 102 are
connected to flanges of the outer panel 104. An opening trim 108 is
attached to each of the flange-connected portions 106, 107. An
interior member 110 is spaced from the inner panel 102 by an
interval in a direction R.sub.2 to the inside of a compartment. The
interior member 110 is, for example, a pillar garnish. Two hollow
bodies 112, 114, made, for example, from aluminum, are disposed
within the aforementioned interval, near the flange-connected
portions 106, 107.
[0087] The structural member 100 receives a load f.sub.3 from, for
example, a rearward occupant 52, in such a manner as indicated in
FIG. 9. The load from a forward occupant is applied to the
structural member 100 in a manner that is substantially symmetrical
to the manner of application of the load f.sub.3 in the
right-and-left direction in FIG. 9. Therefore, the two hollow
bodies 112, 114 are formed in symmetrical angular shapes. It is
preferred that a bottom side portion of each hollow body 112, 114
be fixed to the inner panel 102 so that when a load from the
occupant 52 is applied, a side portion 117 falls or bends toward
the bottom side portion 116.
[0088] In a sixth embodiment as shown in FIG. 10, a structural
member 120 is, for example, a roof side rail extending in a
front-and-rear direction relative to a vehicle body. The structural
member 120 includes an inner panel 122, an outer panel 124 and a
reinforcing panel 126. An interior member 128 is spaced from the
inner panel 122 by an interval in a direction R.sub.3 to the inside
of a compartment. The interior member 128 is, for example, a roof
trim in this embodiment. A hollow body 130, made, for example, from
aluminum, is disposed in the aforementioned interval, extending
over a predetermined length along the structural member 120 in the
front-to-rear direction relative to the vehicle body. The hollow
body 130 is fixed by screws (not shown) to the inner panel 122 of
the roof side rail 120, and supports a grab handle 132.
[0089] The grab handle 132 is mounted on an inward wall portion 134
of the hollow body 130 by screwing a bolt 138 extending through
opposite ends of the grab handles 132 into a nut 136 welded in the
inward wall portion 134. It is preferred that the inner panel 122
and an outward wall portion 135 of the hollow body 130 have holes
that form a hole 139 corresponding to the nut 136 in order to
prevent the bolt 138 from striking the outward wall portion 135 or
the inner panel 122.
[0090] When a load f.sub.4 from an occupant 52 is applied to the
grab handle 132, the load is transmitted by the bolt 138 to the
inward wall portion 134 so that the inward wall portion 134
plastically deforms, absorbing impact energy. Since the bolt 138
and the nut 136 move into the hole 139, the entire hollow body 130
can sufficiently undergo plastic deformation without bottom
striking of the bolt 138 or the nut 136 on the outward wall portion
135 or the inner panel 122. Therefore, the amount of protrusion of
the bolt 138 into the compartment is reduced.
[0091] Since the hollow body 130 extends along the structural
member 120 in the front-and-rear direction relative to the vehicle
body, the holding strength of a portion where the grab handle 132
is mounted is greater than the holding strength provided in a
construction where a grab handle is mounted on a mounting seat such
as a bracket. However, the mounting of the grab handle 132 at
limited sites in the hollow body 130 extending in the
front-and-rear direction of the vehicle does not substantially vary
the energy absorbing characteristics of the hollow body 130 in the
front-and-rear direction. Therefore, substantially uniform energy
absorbing characteristics can be obtained.
[0092] In a seventh embodiment as shown in FIG. 11, a structural
member 140 is, for example, a header extending transversely
relative to a vehicle body. The structural member 140 includes an
inner panel 142 and an outer panel 144. An interior member 146 is
spaced from the inner panel 142 by an interval in a direction
R.sub.4 toward the inside of a compartment. The interior member 146
is, for example, a roof trim in this embodiment. A hollow body 148
is disposed in the aforementioned interval. The hollow body 148 has
a rectangular sectional shape. In this embodiment, upon receiving a
load F.sub.5, the hollow body 148 undergoes plastic deformation
without being displaced.
[0093] Some of the operations of the impact energy absorbing
structure according to the invention will now be explained. In the
first embodiment as shown in FIGS. 1 through 3, when the load
f.sub.1 is applied, mainly the inward wall portion 41 and the side
wall portion 43 of the hollow body 24 deform from the load.
Therefore, the deformation load rises as indicated by B.sub.1 in
the graph of FIG. 12. When the deformation load reaches a peak
value B.sub.2, the non-contact portion 45 of the outward wall
portion 40 starts to be displaced toward the inner panel 26, with
the contact portion 44 acting as a movement center, so that the
deformation load decreases as indicated by B.sub.3. The deformation
load continues to decrease until the non-contact portion 45
sufficiently contacts the inner panel 26 so that the deformation
load reaches a minimum value B.sub.4. When the non-contact portion
45 is in sufficient contact with the inner panel 26, mainly the
inward wall portion 41 and the side wall portions 42, 43
plastically deform. Therefore, the deformation load rises again, to
reach a second peak value B.sub.5. After that, the deformation load
gradually decreases.
[0094] A test was performed on a hollow body wherein the
non-contact portion 45 was not provided but the outward wall
portion 40 was set in substantially full contact with the inner
panel 26. Results are indicated in FIG. 14. After the deformation
load reached point B.sub.2, the hollow body continued deforming
plastically and the deformation load reached a peak value B.sub.6.
The amounts of impact energy absorbed are indicated by areas
defined by the curves in FIGS. 12 and 14. Those areas in FIGS. 12
and 14 are substantially equal. Therefore, it can be seen that by
providing two peak values as indicated in FIG. 12, the maximum peak
value can be reduced.
[0095] In the second embodiment as shown in FIG. 4, when the load
f, is applied, mainly the inward wall portion 67 and the side wall
portion 69 of the hollow body 64 plastically deform from the load.
The deformation load thus rises. Then, the notch 70 induces the
side wall portion 69 to fall or bend in. After the deformation load
reaches a load C.sub.1 indicated in FIG. 12, mainly bending
deformation of the side wall portion 69 proceeds. Therefore, the
deformation load remains substantially constant as indicated by
C.sub.2. After a point C.sub.3 is reached, the deformation load
decreases. Therefore, this embodiment also reduces the maximum peak
value.
[0096] In the fourth embodiment as shown in FIG. 7, provision of
the support portions 88 achieves an earlier rising of an initial
load as indicated by D.sub.2 in FIG. 16. If protruding support
portions are not provided, the deformation load changes as
indicated by D.sub.1. In the fourth embodiment, an additional
deformation load .DELTA.F.sub.1 due to the aforementioned bending
increases the peak load. Therefore, overall energy efficiency
improves. FIG. 17 shows an impact energy absorbing characteristic
curve E.sub.1 of a construction that does not have a support
portion and an impact energy absorbing characteristic curve E.sub.2
of a construction that has support portions and induces
displacement. As can be seen in FIG. 17, the deformation load as
indicated by .DELTA.F.sub.2, the initial load gradient
.theta..sub.1, and the initial load rising displacement as
indicated by .DELTA.S.sub.1 are caused by the bending of the hollow
body with a support portion.
[0097] The impact energy absorbing structure will be described with
reference to the sectional views of FIGS. 18-22 taken on planes
perpendicular to the lengthwise axis of the structure. The impact
energy absorbing structure provided in an upper portion of a motor
vehicle body for absorbing impact energy includes a structural
member 20 extending in the lengthwise direction, an interior member
22 made, for example, from resin and spaced from the structural
member 20 on a compartment side by an interval 36 required for
energy absorption, and a hollow body 24 made, for example, from
metal.
[0098] The structural member 20 includes an inner panel 26, and an
outer panel 28 spaced from the inner panel 26 by an interval
extending toward the outside of the compartment, and a reinforcing
panel 30 disposed between the inner panel 26 and the outer panel
28. Flanges of these panels are connected together by welding,
thereby forming a closed structure.
[0099] In an eighth embodiment as shown in FIG. 18, the structural
member 20 is, for example, a front pillar extending substantially
in a top-and-bottom direction relative to a vehicle body. The
structural member 20 has two flange-connected portions 32, 33. A
front windshield pane 38 can be disposed near a flange-connected
portion 32. An opening trim 39 can be connected to the other
flange-connected portion 33.
[0100] The interior member 22 is, for example, a pillar garnish and
is spaced from the inner panel 26 by the interval 36. The interval
36 varies in size depending on locations. The size of the interval
36 may be determined, for example, within the range of 5 to 40
mm.
[0101] The hollow body 24 is disposed within the interval 36, near
the flange-connected portion 33. The hollow body 24 is formed, for
example, of aluminum by extrusion. The hollow body 24 has an
angular configuration in a section taken on a plane perpendicular
to the lengthwise axis thereof. The angular configuration is
substantially formed by an inward wall portion 41 facing the
interior member 22, an outward wall portion 40 facing the inner
panel 26 of the structure member, and two side wall portions 42, 43
connecting between the inward wall portion 41 and the outward wall
portion 40. The thickness of the individual wall portions of the
hollow body 24 may be determined as a constant thickness of, for
example, about 1 mm or may vary within the range of, for example,
about 1 to 3 mm. As shown in the perspective view of FIG. 22, the
hollow body 24 extends along the length of the interior member
22.
[0102] The hollow body 24 is adhered to an outward surface 23 of
the interior member 22 so that the axis of the hollow body 24
extends in the direction of the length of the structural member 20.
The hollow body 24 is disposed within the interval 36. In the
eighth embodiment as shown in FIGS. 18 and 19, the hollow body 24
is adhered to the outward surface 23 of the interior member 22, by
an adhesive 60 at the side wall portion 42 and by an adhesive 61 at
the side wall portion 43.
[0103] The adhesives 60, 61 are, for example, a synthetic
rubber-based hot melt adhesive in the eighth embodiment shown in
FIGS. 18 and 19. The adhesive may be a synthetic rubber based
adhesive, a urethane-based adhesive, an epoxy-based adhesive, an
acryl-based adhesive, a polyolefin-based adhesive, a
polyester-based adhesive or a polypropylene-based adhesive, as
examples.
[0104] The adhesives 60, 61 are applied over the entire length of
the hollow body 24. However, it is not necessary to uniformly apply
the adhesive at each location in the lengthwise direction. As is
apparent from FIGS. 18 and 19, the hollow body 24, formed, for
example, by extrusion forming, has a constant sectional shape and
constant dimensions over the entire length, but the sectional shape
and the dimensions of the interior member 22 may vary in the
lengthwise direction. Therefore, to secure appropriate adhesion, it
is preferred that the amount of the adhesive 60 applied between the
side wall portion 42 and the interior member 22 as indicated in
FIG. 19 be increased or the adhesive 61 between the side wall
portion 43 and the interior member 22 be pressed into the gap
between the interior member 22 and the inward wall portion 41 as
indicated in FIG. 19.
[0105] Since the adhesive 61 is applied to an acute angle portion
formed by the interior member 22 and the side wall portion 43 in
FIGS. 18 and 19, the angle portion maintains an applied state. On
the other hand, the angle formed by the interior member 22 and the
side wall portion 42 is essentially obtuse, so that it is difficult
to keep the adhesive 60 in the applied state. Therefore, a
restricting device 49 is provided for keeping the adhesive in the
applied state. The amount of the adhesive 60 applied can be
restricted by a height of the restricting device 49 and a distance
of the restricting device 49 from the side wall portion 42.
Furthermore, the area of the adhesive applied can also be
restricted by the distance of the restricting device 49 from the
side wall portion 42. The restricting device 49 is, for example,
rib protruding integrally from the interior member 22 in the eighth
embodiment.
[0106] In the example of the eighth embodiment discussed above,
since the interior member 22 is made from a resin and the hollow
body 24 is made, e.g., from a metal, the interior member 22 and the
hollow body 24 have different ductilities. Therefore, if a load
equal to or greater than a predetermined value is transmitted to
the hollow body 24 by the interior member 22, a relative
displacement occurs at adhering portions between the two members,
so that the sheering force based on the relative displacement acts
on the adhesives 60, 61. The reaction force to the sheering force
also absorbs impact energy, thereby achieving energy absorbing
characteristics different from the original energy absorbing
characteristics of the hollow body 24. Furthermore, a change in the
adhering manner can also change the energy absorbing
characteristics.
[0107] Since the hollow body 24 can be formed into any desired
sectional shape through, for example, extrusion forming, the hollow
body 24 can easily be adapted to the interval 36 between the
structural member 20 and the interior member 22. Furthermore,
because it is possible to select a location of adhesion to the
interior member 22 and an adhesion area from a wide range of
choices, and because it is possible to achieve various
characteristics by selecting a particular wall thickness or a
particular sectional shape of the hollow body 24, the degree of
freedom in selecting energy absorbing characteristics is high.
[0108] The interior member 22 can easily be attached to the
structural member 20. First, the adhesives 60, 61 are applied to
required portions of the outward surface 23 of the interior member
22. The hollow body 24 is then adhered to the interior member 22 by
the adhesives 60, 61. Alternatively, after the hollow body 24 is
placed on a required location on the outward surface 23 of the
interior member 22, the adhesives may be applied to adhere the
hollow body 24 to the interior member 22. After that, the interior
member 22, together with the hollow body 24, can easily be attached
to the structural member 20.
[0109] If the hollow body 24 is adhered at a plurality of portions
thereof to the interior member 22, a sheering force will act on
each of the adhered portions so that a reaction force based on the
sheering force is produced. Thereby, different energy absorbing
characteristics can easily be obtained.
[0110] In a ninth embodiment shown in FIG. 20, a hollow body 24 is
adhered to an interior member 22 by an adhesive 60 between a side
wall portion 42 of the hollow body 24 and the interior member 22,
an adhesive 61 between a side wall portion 43 and the interior
member 22 and, further, by an adhesive 62 provided locally between
an inward wall portion 41 and the interior member 22. The amount of
the adhesive 62 applied can be restricted by a restricting device
51 provided on the interior member 22 in the form of, for example,
knurls.
[0111] In a tenth embodiment as shown in FIG. 21, a hollow body 24
is adhered to an interior member 22 at a surface of the hollow body
24 that receives loads applied to the hollow body 24. The load
which is applied to the hollow body 24, the energy of which needs
to be absorbed, is from an occupant. A head portion 52 of an
occupant may be one of the load sources. Therefore, the hollow body
24 is adhered to the interior member 22, at locations or portions
corresponding to the head portion 52 of an occupant. More
specifically, as shown in FIG. 21, the hollow body 24 is adhered to
the interior member 22 by an adhesive 60 between a side wall
portion 42 of the hollow body 24 and the interior member 22, an
adhesive 61 between a side wall portion 43 and the interior member
22, and, further, by an adhesive 63 between the interior member 22
and the entire surface of an inward wall portion 41 that
substantially corresponds to the head portion 52 of an occupant.
The amount of the adhesive 63 applied can be restricted by a
restricting device 51 provided on the interior member 22. The
adhesives 60, 61 are applied over the length of the hollow body 24
to retain the hollow body 24.
[0112] In a case where the hollow body 24 is adhered to the
interior member 22 as in the eight, ninth and tenth embodiments,
when a load is transmitted to the hollow body 24 by interior member
22, the hollow body 24 starts to be deformed to absorb impact
energy and, simultaneously sheering forces act on the adhesives 60,
61, 62, 63 so that the adhesives 60, 61, 62, 63 also absorb impact
energy even during an initial period of application of the load.
Therefore, energy absorbing characteristics with a sharp rising
load can be obtained, and an increased peak value of load can be
obtained. Consequently, the displacement required for energy
absorption can be reduced. Since a reduction in the displacement
required for energy absorption means a reduction of the required
size of the interval 36 between interior member 22 and the
structural member 20, the space of the compartment can be
increased.
[0113] In a case wherein the hollow body 24 is adhered, at the two
side wall portions 42, 43 to the interior member 22 as in the
eighth embodiment, when a load is transmitted to the hollow body 24
by the interior member 22, the inward wall portion 41 of the hollow
body 24 first starts to deform. Then, as the side wall portions 42,
43 deform, sheering forces act on the adhesives 60, 61. Therefore,
the use of adhesives 60, 61 can achieve energy absorbing
characteristics in which the rise of energy absorption is delayed
during an initial period and in which a large amount of energy can
be absorbed during a later period. Therefore, energy absorption
fully utilizing the deformation displacement can be
accomplished.
[0114] If the interior member 22 is provided with the restricting
device 49, it becomes easy to control the energy absorbing
characteristics based on appropriate amounts of adhesive by
restricting the amount of the adhesive 60 applied or the area of
the application.
[0115] In a case in which the hollow body 24 is adhered to the
interior member 22 at a surface of the hollow body 24 that receives
the load applied to the hollow body 24, the thickness of the hollow
body 24 can be determined as follows. In FIG. 18, a displacement
S.sub.2 that the load source 52 is allowed to make for energy
absorption if a load from the load source 52 is applied in a
direction f.sub.7, is greater than a displacement S.sub.3 that the
load source 52 is allowed to make for energy absorption if the load
is applied in a direction f.sub.6. Therefore, the wall thickness,
shape and the like of the hollow body 24 are determined such that a
predetermined impact energy can be absorbed by or within the
displacement S.sub.2. Although the displacement decreases with
respect to the load in the direction f.sub.6, such a displacement
decrease can be offset by an increase in the reaction load achieved
by adhering to the interior member 22 portions of the hollow body
24 that receive load. In the eighth embodiment, the displacement
S.sub.2 is, for example, about 25 mm while the displacement S.sub.3
is, for example, about 17 mm.
[0116] Experiment results will be presented below. FIG. 23
indicates a characteristic curve G in a case where a hollow body as
shown in FIGS. 18 and 19 was adhered, at a load-receiving surface
thereof, to the interior member, and a characteristic curve H in a
case where a hollow body as shown in FIGS. 18 and 19 was fixed or
fastened to the inner panel of the structure member. Loads were
applied in the direction f.sub.6 indicated in FIG. 18 in both
cases. The rising of an initial load is greater in the
characteristic curve G than in the characteristic curve H. The peak
load is also greater in the characteristic curve G. Thus, the
reaction load can be qualitatively adjusted by adhering the hollow
body to the interior member.
[0117] FIG. 24 indicates a characteristic curve I in a case (FIG.
21) where a hollow body having a configuration as shown in FIG. 18
was adhered at a load-receiving surface thereof to the interior
member, a characteristic curve J in a case (FIG. 20) where an
identical hollow body was adhered at three sites in a section
thereof to the interior member, and a characteristic curve K in a
case (FIGS. 18 and 19) where an identical hollow body was adhered
at two sites in a section thereof to the interior member. Loads
were applied in the direction f.sub.6 indicated in FIG. 18. As can
be seen from the curves, the larger the area on the hollow body
restricted by adhesive, the greater the rising of an initial load.
Thus, the reaction load can be qualitatively adjusted depending on
the amount of surface area at which the hollow body is adhered to
the interior member.
[0118] FIG. 25 indicates another effect achieved in the case where
the hollow body was adhered at its load-receiving surface to the
interior member. The initial load increases if the hollow body is
adhered to the interior member, as indicated in FIG. 23. This means
that if the initial value in the case of the hollow body being
adhered only needs to be a value equal to the initial value in the
case of the hollow body fastened to the interior member, the wall
thickness of the hollow body adhered to the interior member can be
reduced. If the wall thickness of the hollow body is not reduced,
the entire displacement can be increased while the same initial
load condition is maintained by reducing the thickness (overall
dimension) of the hollow body itself. For example, while a hollow
body undergoes bottom striking after a certain displacement
S.sub.5, a hollow body having a reduced thickness while retaining
the initial load conditions enjoys an entire displacement increased
by a displacement .DELTA.S.sub.4, thereby increasing the
displacement before bottom striking. In this manner, it is possible
to achieve efficient energy absorption while securing the same
initial load, by increasing the effective displacement.
[0119] Referring to the sectional views of FIGS. 26, 27 and 28, an
impact energy absorbing structure provided in an upper portion of a
vehicle body for absorbing impact energy. The structure includes a
structural member 20 having an inner panel 26 and extending in the
lengthwise direction, an interior member 94 spaced in a direction
to the inside of a compartment from the inner panel 26 by an
interval 36 required for energy absorption, and a hollow body 24
disposed in the interval 36.
[0120] In an eleventh embodiment as shown in FIG. 26, a structural
member 20 is, for example, a front pillar extending in a
top-and-bottom direction relative to a vehicle body. In addition to
the inner panel 26, the structural member 20 has an outer panel 28
spaced from the inner panel 26 by an interval extending toward the
outside of the compartment, and a reinforcing panel 30 disposed
between the panels 26 and 20. Flanges of these panels are connected
together by welding so as to form a closed structure in a section
taken on a plane perpendicular to a lengthwise axis of the
structural member 20. The structural member 20 has two
flange-connected portions 32, 33. A front windshield pane 38 can be
disposed near a flange-connected portion 32. An opening trim 39 can
be connected to the other flange-connected portion 33. A hollow
body 24 is disposed near the flange-connected portion 33.
[0121] In the eleventh embodiment as shown in FIGS. 26-28, the
hollow body 24 is, for example, a metallic member formed from
aluminum by extrusion forming. The hollow body 24 is formed so as
to have an angular sectional shape. The hollow body 24 has an
inward wall portion 41 facing an outward surface 96 of the interior
member 94, an outward wall portion 40 facing the inner panel 26,
and two side wall portions 42, 43 connecting between the inward
wall portion 41 and the outward wall portion 40. The outward wall
portion 40 of the hollow body 24 is spaced from the inner panel 26
by gaps. The gaps a.sub.3, a.sub.4, b.sub.3, b.sub.4 therebetween
vary in size in the lengthwise direction relative to the structural
member 20. It is preferred that the hollow body 24 is formed so
that the thickness of the hollow body 24 locally varies in a
section thereof taken on a plane perpendicular to the lengthwise
axis. In the eleventh embodiment shown in FIG. 26, the hollow body
24 is formed so that the hollow body 24 is thickest in the inward
wall portion 41.
[0122] The interior member 94 is, for example, a pillar garnish.
The interior member 94 fixes the hollow body 24 by the outward
surface 96 of the interior member 94. This fixation can be
accomplished, for example, by adhering the inward wall portion 41
of the hollow body 24 to the outward surface 96 of the interior
member 94 with an adhesive, or by inserting a plurality of
projections 98 protruding from the interior member 94 toward the
outside, into corresponding holes (not shown) formed in the hollow
body 24, as indicated in FIG. 26, and then thermally riveting the
projections 98.
[0123] The interior member 94 is formed so that the thickness
thereof is not uniform in a section taken on a plane perpendicular
to a lengthwise axis of the structural member 20. In the eleventh
embodiment as shown in FIG. 26, wherein a direction f.sub.6 of a
load that is expected to act on the interior member 94 at a site
near the flange-connected portion 33 and a direction f.sub.7 of a
load that is expected to act on the interior member 94 at a site
remote from the flange-connected portion 33 are indicated, the
interior member 94 is formed so that the thickness of a thin
portion 99 corresponding to the load direction f.sub.7, not the
load direction f.sub.6, is smaller than the thicknesses of the
other portions.
[0124] That is, the interior member 94 gradually becomes thinner
from end portions 91, 92 toward the thin portion 99. For example,
the thickness of the thin portion 99 may be about 0.5-1.5 mm
smaller than that of the end portions 91, 92.
[0125] The interior member 94 has two mounting seats 97, as shown
in FIG. 28, that are formed in an intermediate portion and an end
portion of the interior member 94 in the lengthwise direction. The
hollow body 24 is divided into two sections by the mounting seat 97
formed in the intermediate portion. Each of the mounting seats 97
extends to the vicinity of the inner panel 26, and carries a clip
150 attached thereto. The interior member 94 is attached to the
structural member 20 by inserting the clips 150 of the mounting
seats 97 into holes of the inner panel 26.
[0126] The operation of the eleventh embodiment will be described
below.
[0127] If a load is applied from an occupant 52 in the direction
f.sub.7 indicated in FIG. 26 such that the interior member 94
deforms in the direction of the load, the hollow body 24 deforms so
that an initial load M.sub.1 occurs as indicated in FIG. 29. Since
the hollow body 24 does not move relative to the inner panel 26
during deformation of the interior member 94 in the direction
f.sub.7, the force-receiving area of the hollow body 24 remains
unchanged. Therefore, the reaction load is maintained as indicated
by M.sub.2.
[0128] According to the invention, since the thickness of the
interior member 94 is reduced in the thin portion 99, application
of a load in the direction f.sub.6 deforms the interior member 94
in such a manner that the interior member 94 falls or bends
counterclockwise in FIG. 26, with the thin portion 99 acting as a
fulcrum, thereby displacing the hollow body 24 relative to the
inner panel 26. Therefore, the deformation of the hollow body 24
provides an initial load M.sub.1, but the force-receiving area of
the hollow body 24 decreases. Therefore, after a peak load M.sub.3
is reached, the reaction load decreases as indicated by M.sub.4.
When the displacement of the hollow body 24 is stopped, the
reaction load becomes a minimum value M.sub.5 and then increases
again as indicated by M.sub.6. Since the hollow body 24 is
displaced by deformation of the interior member 94, the
displacement becomes S.sub.8, which is greater than displacement
S.sub.7 obtained in a structure where displacement of a hollow body
is not intended.
[0129] If a load is applied in the direction f.sub.6 as indicated
in FIG. 26, the interval between the occupant 52 and the
flange-connected portion 33 becomes S.sub.7. If a load is applied
in the direction f.sub.7, the interval between the occupant 52 and
the inner panel 26 becomes S.sub.6. In the structure shown in FIG.
26, S.sub.6>S.sub.7. If the interior member 94 deforms in the
load direction f.sub.6, the energy absorbing body brings about an
initial load M.sub.1. In this case, the force-receiving area
remains unchanged, so that the reaction load is maintained at
N.sub.1 as indicated in FIG. 30. Then, at a displacement S.sub.7,
the interior member 94 contacts the flange-connected portion 33, so
that the reaction load rapidly increases to N.sub.2. According to
the invention, however, a load in the direction f.sub.6 causes the
interior member 94 to deform in such a manner that the interior
member 94 falls or bends in with the thin portion 99 serving as a
turning center. The hollow body 24 is thereby deformed. Therefore,
the occurring load exhibits a characteristic as indicated by
M.sub.1, M.sub.3, M.sub.4, M.sub.5 and M.sub.6, with a peak load
reduced by .DELTA.F.sub.3. On the other hand, if a load is applied
in the direction f.sub.7, the inward wall portion 41 of the hollow
body 24 receives load as the interior member 94 deforms since the
thin portion 99 of the interior member 94 is faced by a large
thickness portion of the hollow body 24. Load is then transmitted
from the inward wall portion 41 to the two side wall portions 42,
43 and the outward wall portion 40 of the hollow body 24.
Deformation progresses while the force-receiving area remains
unchanged. Thus, the occurring load is maintained as indicated by
O.sub.1.
[0130] If the thickness of the inward wall portion 41 of the hollow
body 24 is substantially equal to the thickness of the other
portions of the hollow body 24, the load provided by the energy
absorbing body becomes as indicated by M.sub.1 and M.sub.2 in FIG.
31 when a load applied in the direction f.sub.6 deforms the
interior member 94 in a falling or bending manner with the thin
portion 99 serving as a fulcrum or turning center. In contrast, in
the embodiment as shown in FIG. 1, the thickness of the inward wall
portion 41 of the hollow body 24 is greater than the thickness of
the other portions thereof, so that the load provided by the energy
absorbing body during the falling or bending deformation of the
interior member 94 with the thin portion 99 serving as a fulcrum or
turning center becomes as indicated by P1, P2, P3 in FIG. 31. Thus,
a characteristic is obtained that the rising slope is increased by
.theta..sub.2 and the peak load is increased by .DELTA.F.sub.4.
[0131] As can be understood from the above description, in the
eleventh embodiment, when the interior member 94 is deformed by
application of a load equal to or greater than a predetermined
value, the hollow body 24 fixed to the outward surface 96 of the
interior member 94 is displaced together with the interior member
94 in the direction of the load. When the hollow body 24 contacts
the inner panel 26 of the structural member 20, the hollow body 24
starts to plastically deform, thereby absorbing energy.
[0132] Since the thickness of the interior member 94 locally
varies, application of a load to a portion of the interior member
94 that is remote from the thin portion 99 of the interior member
94 causes the interior member 94 to deform with the thin portion 99
serving as a fulcrum or turning center. As the interior member 94
thus deforms, the hollow body 24 is displaced toward the inner
panel 26 of the structural member 20. Therefore, a portion of the
hollow body 24 that deforms can be forcibly restricted by the
interior member 94.
[0133] If a load is applied to the thin portion 99 of the interior
member 94, the entire interior member 94 is displaced in the
direction of the load, deforming the hollow body 24. Therefore, it
becomes easy to set an amount of displacement or configuration
required for energy absorption regarding the hollow body 24 and a
sufficient amount of energy absorption can be secured. There is no
need to provide a hollow body with the required energy absorbing
characteristics or with deforming characteristics in various load
directions. Thus, the shape and structure of the hollow body 24 can
be simplified.
[0134] Since the hollow body 24 has a great ductility, and starts
to plastically deform at an earlier timing relative to an amount of
displacement, a sufficient amount of impact energy can be absorbed
during an initial period of load application. Furthermore, since
the hollow body 24 can be formed by extrusion forming, an energy
absorbing body having a required shape can easily be formed.
[0135] If a load is applied to a portion remote from the
flange-connected portion 33, the entire interior member 94 is
deformed in the direction of the load, whereby the hollow body 24
is deformed. Since there is no possibility that during this
deformation, the interior member 94 or the hollow body 24 will
strike one of the flange-connected portions, that is, the
flange-connected portion 33, and receive a reaction force from the
flange-connected portion 33, it is possible to secure a long stroke
and to increase the area of the hollow body 24 that faces the inner
panel 26 of the structural member 20. Therefore, impact energy
absorption is performed with low reaction loads and long
displacements. On the other hand, if a load is applied to a portion
of the interior member 94 which is remote from the thin portion 99
but close to the flange-connected portion 33, the interior member
94 deforms with the thin portion 99 serving like a fulcrum or
turning center, thereby displacing the hollow body 24 away from the
flange-connected portion 33. The hollow body 24 then contacts the
inner panel 26 and deforms, absorbing impact energy. In this case,
the displacement is increased by an amount corresponding to the
displacement of the hollow body 24 away from the flange-connected
portion 33. Therefore, energy absorption is performed with the
increased displacement and increased reaction loads.
[0136] While the present invention has been described with
reference to what are presently considered to be preferred
embodiments thereof, it is to be understood that the invention is
not limited to the disclosed embodiments or constructions. To the
contrary, the invention is intended to cover various modifications
and equivalent arrangements. In addition, while the various
elements of the disclosed invention are shown in various
combinations and configurations, which are exemplary, other
combinations and configurations, including more, less or only a
single element, are also within the spirit and scope of the
invention.
* * * * *