U.S. patent application number 09/729923 was filed with the patent office on 2001-11-15 for three-dimensional air bags for vehicles.
Invention is credited to Asanuma, Junichi, Hirano, Tatuo, Ichino, Rie, Ido, Masaru, Kuriyama, Yuji, Ogawa, Hiroshi, Okada, Yasushi, Suzuki, Kazumasa, Tajima, Kou.
Application Number | 20010040368 09/729923 |
Document ID | / |
Family ID | 27341261 |
Filed Date | 2001-11-15 |
United States Patent
Application |
20010040368 |
Kind Code |
A1 |
Okada, Yasushi ; et
al. |
November 15, 2001 |
Three-dimensional air bags for vehicles
Abstract
A three-dimensional airbag for a vehicle having a main panel
having a generally elongated shape. The main panel includes a pair
of generally symmetric first portions extending from opposite sides
of a fold line and a pair of second portions. A subpanel is secured
to the main panel to form a hollow body. The first portions of the
main panel are joined to each other along their edges. The edges of
the second portions are secured to the edge of the subpanel to
close the open front end of the hollow body to form an air bag. The
air bag may further include at least one of a baffle for
controlling the flow of air within the bag during inflation and a
tether assembly for controlling the opening of the air bag.
Inventors: |
Okada, Yasushi; (Aichi-ken,
JP) ; Ido, Masaru; (Aichi-ken, JP) ; Hirano,
Tatuo; (Aichi-ken, JP) ; Kuriyama, Yuji;
(Aichi-ken, JP) ; Suzuki, Kazumasa; (Alichi-ken,
JP) ; Ogawa, Hiroshi; (Alichi-ken, JP) ;
Ichino, Rie; (Aichi-ken, JP) ; Tajima, Kou;
(Aichi-ken, JP) ; Asanuma, Junichi; (Aichi-ken,
JP) |
Correspondence
Address: |
PILLSBURY WINTHROP LLP
1100 NEW YORK AVENUE NW
9TH FLOOR
WASHINGTON
DC
20005
US
|
Family ID: |
27341261 |
Appl. No.: |
09/729923 |
Filed: |
December 6, 2000 |
Current U.S.
Class: |
280/743.2 ;
280/728.3 |
Current CPC
Class: |
B60R 21/233 20130101;
B60R 2021/23324 20130101; B60R 21/2346 20130101 |
Class at
Publication: |
280/743.2 ;
280/728.3 |
International
Class: |
B60R 021/16 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 7, 1999 |
JP |
HEI 11-347693 |
Dec 12, 1999 |
JP |
HEI 11-351623 |
Oct 7, 2000 |
JP |
2000-239043 |
Claims
What is claimed is:
1. An airbag for a vehicle, comprising: a main panel having a
generally elongated shape and a fold line, the main panel
comprising: a pair of first portions extending from opposite sides
of the fold line, wherein each of the pair of first portions is
generally symmetric to the other, each of the first portions having
a first end adjacent the boundary line and a second end spaced from
the boundary line, wherein each of the first portions includes a
first edge and a second edge, a pair of second portions, wherein
one of the second portions extends from the second of one of the
first portions and another of the second portions extends from the
second end of the other of the first portions, wherein each of the
second portions includes a peripheral edge, wherein the pair of
first portions are secured together along the first edges and the
second edges to form a hollow body having an open end; and a
subpanel secured to the main panel, wherein the subpanel is secured
to the main panel along the peripheral edges of the pair of second
portions, wherein the subpanel is located opposite the air inlet
covering the open end.
2. The air bag according to claim 1, wherein the subpanel has a
shape corresponding to a combined shape of the pair of second
portions.
3. The air bag according to claim 1, further comprising: an air
control assembly located within the hollow body for controlling the
flow of air within the air bag during an inflation operation.
4. The air bag according to claim 1, wherein the air control
assembly includes a baffle located within the hollow body adjacent
the air inlet.
5. The air bag according to claim 4, wherein the baffle comprises:
a generally tubular body located adjacent the air inlet, wherein
the tubular body has a pair of open ends, wherein the tubular body
directs air from the air inlet into upper and lower portions of the
hollow body through the open ends.
6. The air bag according to claim 5, wherein the tubular body has a
larger cross-sectional area adjacent one open end compared to the
cross sectional area adjacent the other open end.
7. The air bag according to claim 6, wherein a cross sectional area
of a middle portion of the tubular body is greater than the
cross-sectional area of the open ends.
8. The air bag according to claim 5, wherein the tubular body is
secured to the main panel adjacent the air inlet.
9. The air bag according to claim 5, wherein the tubular body
includes a curved surface for directing air from the air inlet to
the open ends.
10. The air bag according to claim 9, wherein the tubular body has
a larger cross-sectional area adjacent one open end compared to the
cross sectional area adjacent the other open end.
11. The air bag according to claim 10, wherein a cross sectional
area of a middle portion of the tubular body is greater than the
cross-sectional area of the open ends.
12. The air bag according to claim 1, further comprising: a
reinforcing member secured to the main panel adjacent the air
inlet, wherein the reinforcing member surrounds the air inlet.
13. The air bag according to claim 1, further comprising: an air
bag opening control assembly for controlling the shape of the
airbag during inflation.
14. The air bag according to claim 13, wherein the air bag control
assembly includes a tether assembly located within the hollow
body.
15. The air bag according to claim 14, wherein the tether assembly
divides the hollow body into an upper compartment and a lower
compartment.
16. The air bag according to claim 14, wherein the tether assembly
is spaced from first edges and second edges of the first portions,
wherein the spacing between one of the first and second edges and
the tether assembly is greater than the spacing between the other
of the first and second edges and the tether assembly.
17. The air bag according to claim 1, wherein the main panel
includes at least one vent hole formed therein.
18. An air bag for a vehicle, comprising: a main panel having an
air inlet formed therein; a subpanel secured to the main panel,
wherein the subpanel and main panel form a hollow inflatable body;
and an air control assembly located within the hollow body for
controlling the flow of air within the air bag during an inflation
operation.
19. The air bag according to claim 18, wherein the air control
assembly includes a baffle located within the hollow body adjacent
the air inlet.
20. The air bag according to claim 19, wherein the baffle
comprises: a generally tubular body located adjacent the air inlet,
wherein the tubular body has a pair of open ends, wherein the
tubular body directs air from the air inlet into upper and lower
portions of the hollow body through the open ends.
21. The air bag according to claim 20, wherein the tubular body has
a larger cross-sectional area adjacent one open end compared to the
cross sectional area adjacent the other open end.
22. The air bag according to claim 21, wherein a cross sectional
area of a middle portion of the tubular body is greater than the
cross-sectional area of the open ends.
23. The air bag according to claim 20, wherein the tubular body is
secured to the main panel adjacent the air inlet.
24. The air bag according to claim 20, wherein the tubular body
includes a curved surface for directing air from the air inlet to
the open ends.
25. The air bag according to claim 24, wherein the tubular body has
a larger cross-sectional area adjacent one open end compared to the
cross sectional area adjacent, the other open end.
26. The air bag according to claim 25, wherein a cross sectional
area of a middle portion of the tubular body is greater than the
cross-sectional area of the open ends.
27. The air bag according to claim 18, wherein the main panel
includes at least one vent hole formed therein.
28. An airbag for a vehicle, comprising: a main panel having an air
inlet formed therein; a subpanel secured to the main panel, wherein
the subpanel and main panel form a hollow inflatable body; and an
air bag opening control assembly for controlling the shape of the
airbag during inflation.
29. The air bag according to claim 28, wherein the air bag control
assembly includes a tether assembly located within the hollow
body.
30. The air bag according to claim 29, wherein the tether assembly
divides the hollow body into an upper compartment and a lower
compartment.
31. The air bag according to claim 29, wherein the tether assembly
is spaced from first edges and second edges of the first portions,
wherein the spacing between one of the first and second edges and
the tether assembly is greater than the spacing between the other
of the first and second edges and the tether assembly.
32. The air bag according to claim 29, wherein the main panel
includes at least one vent hole formed therein.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application relates to and claims priority under 35
U.S.C. .sctn.119 on Japanese Patent Application Nos. 11/347693,
filed Dec. 7, 1999, 11/351623, filed Dec. 12, 1999 and 12/239043,
filed Oct. 7, 2000.
FIELD OF THE INVENTION
[0002] The present invention relates to a three-dimensional air bag
for a vehicle. More particularly, the present invention relates to
a three-dimensional air bag that can easily be made by joining a
plurality of sections together, and is useful for protecting the
passengers in a motor vehicle.
BACKGROUND OF THE INVENTION
[0003] A three-dimensional air bag 12 according to the prior art is
shown in FIGS. 1A and 1B. When inflated, the air bag 12 has a
closed substantially rectangular shape. The air bag 12 has a
rectangular base wall 14, an upper wall 16, a lower wall 18, a
front wall 17, and a pair of side walls 20 and 22. The side walls
20 and 22 have an enlarged area adjacent the front wall 17, as
shown in FIG. 1B.
[0004] The air bag 12 is assembled by sewing three panels together
along their edges. The three panels include a main panel 24, which
forms the base wall 14, upper wall 16, front wall 17 and lower wall
18, and a pair of side panels 26 and 28, which form the side walls
20 and 22, respectively, as shown in FIG. 1A. The main panel 24 has
an air inlet 15 and a plurality of attaching holes 31. Each side
panel 26 and 28 has a vent hole 27. There are three reinforcing
cloth pieces sewn on the main panel 24. A first reinforcing cloth
piece 30 is secured adjacent the air inlet 15. A pair of second
reinforcing cloth pieces 32 are secured adjacent the end portions
of the main panel 24, as shown in FIG. 1A. Each of the side panels
26 and 28 has a third reinforcing cloth piece 34 sewn thereto
opposite the enlarged area, as shown in FIG. 1A. The air bag 12 has
a total of five reinforcing cloth pieces.
[0005] The air bag 12, however, has numerous fabrication drawbacks.
First, after fastening one of the side panels 26 or 28 to the main
panel 24, it is necessary to manually adjust the position of the
other side panel 26 or 28 to ensure the accurate positioning before
fastening to the main panel 24. Therefore, it is essential to feed
the bag manually through a sewing machine. As such, it is difficult
to fabricate the air bag 12 by an automated process including the
mechanical feeding of the work. Second, the air bag 12 requires at
least three panels 24, 26 and 28. Third, the panels can be prepared
only at a relatively low yield with a large waste of material,
since the main panel 24 is by far greater in length than the side
panels 26 and 28. Fourth, the fastening of the reinforcing cloth
pieces 30, 32 and 34 is both labor and time intensive, since at
least one reinforcing piece has to be fastened to each panel 24, 26
or 28 adjacent the base wall 14.
OBJECTS OF THE INVENTION
[0006] It is an object of the present invention to provide an
airbag that overcomes the above-identified deficiencies.
[0007] It is an object of this invention to provide a
three-dimensional air bag for a vehicle which can easily be made by
an automatic process including the mechanical feeding of the
work.
[0008] It is another object of the present invention to provide an
airbag having an assembly therein for controlling the flow of air
within the airbag during inflation.
[0009] It is another object of the present invention to provide an
airbag having an assembly for controlling the inflation of the
airbag.
SUMMARY OF THE INVENTION
[0010] The present invention is directed to an air bag formed by a
main panel having an air inlet and a subpanel joined to the main
panel. The main panel has a pair of first portions that are
symmetric to each other with respect to the boundary located
adjacent to the air inlet, and a pair of second portions extending
in opposite directions from the first portions respectively. The
subpanel has a shape identical to the combined shape of the second
portions of the main panel, each of the first portions of the main
panel have a pair of edges extending from the boundary to one of
the second portions. The first portions being joined to each other
along the edges adjoining each other to form with the second
portions a hollow body having an opening at the front end remote
from the air inlet. The subpanel being joined to the second
portions of the main panel along their edges to close the
opening.
[0011] In accordance with the present invention, the main panel has
the first portions joined to each other along the adjoining edges,
and is joined to the subpanel along the edges of the second
portions and the edge of the subpanel. There is no overlapping
portion between the joint between the first portions of the main
panel and the joint between the main panel and the subpanel. With
the present arrangement, there is no necessity to manually remove
any panel to avoid any wrong joining when forming any such joint.
Therefore, it is easy to employ an automatic sewing process
including the mechanical feeding of the work for joining the
panels, or panel portions, to make the air bag of this invention.
It was possible to make any known air bag by an automatic sewing
process involving the vertical motions of a needle.
[0012] The air bag according to the present invention has a smaller
number of component parts. It essentially consists of only two
panels, while at least three panels are required for forming any
known air bag. The panels forming the air bag of this invention can
be prepared at an improved yield. The main panel is relatively
small in length, as the front wall of the air bag is formed by the
subpanel. Moreover, it is sufficient to apply a single piece of
reinforcing cloth to the main panel, since the main panel forms
both a base wall surrounding the air inlet and the whole area
surrounding the base wall. No reinforcing cloth is required for the
subpanel. Thus, the air bag of this invention has a still smaller
number of component parts and requires only a still smaller amount
of time and labor for its fabrication.
[0013] The air bag according to the present invention may further
include a tether having a pair of transverse edges secured to the
base and front walls. The tether is adapted to divide the interior
into an upper and a lower chamber upon inflation of the air bag.
The tether is preferably sized to have a larger spacing on one side
of the air bag. The tether as described prevents any undesirably
heavy downward load from bearing upon any intefering object below
the expanding lower compartment of the inflated air bag even after
it has been fully stretched. More specifically, the tether
preferably has along its edge secured to the front wall a width
substantially equal to that of the air bag as inflated, and is
partly cut away along its edge facing the exterior of the vehicle
toward the air inlet of the air bag. Moreover, the tether
preferably occupies an area of 50% to 80% in the plane in which it
extends in the air bag as inflated.
[0014] According to another aspect of this invention, there is
provided an air bag for an air bag device mounted in a dashboard.
The air bag includes a baffle covering a gas inlet. The baffle
controls the flow of gas within the airbag. The gas entering the
air bag through the inlet during the initial stage of inflation
strikes against the baffle and is divided into a stream of gas
flowing forward and a stream of gas flowing backward. The baffle
can be formed from only a small amount of material, since it does
not have to be of any greatly enlarged length, but has only to be
formed with a portion having a concavely curved inner surface
facing the gas inlet. Nevertheless, it enables the air bag to
extend backwardly along the surface of the dashboard during the
initial stage of its inflation.
[0015] The cross-sectional area SF of the baffle at the front end
is larger than the cross-sectional area SB at the back end. With
this arrangement, a stream of inflating gas flowing forward in the
bag is larger than a stream of gas flowing backward. This enables
the air bag to have a portion protrude from the dashboard and
extend backward quickly along a windshield, so that another portion
thereof facing the passenger may become upright quickly.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] The present invention will be described in conjunction with
the following drawings in which like reference numerals designate
like elements and wherein:
[0017] FIG. 1A is a top plan view of the unassembled three panels
forming a conventional air bag;
[0018] FIG. 1B is a perspective view of the conventional air bag of
FIG. 1A in an assembled and inflated condition;
[0019] FIG. 2A is a top plan view of the unassembled panels forming
an air bag in accordance with an embodiment of the present
invention;
[0020] FIG. 2B is a top plan view of the assembled panels of the
air bag of FIG. 2A;
[0021] FIG. 3 is a perspective view of the air bag of FIGS. 2A and
2B in an inflated condition;
[0022] FIG. 4 is a schematic sectional view showing the air bag of
FIGS. 2A and 2B in an uninflated stored condition;
[0023] FIG. 5A is a top plan view of the unassembled panels forming
an air bag in accordance with another embodiment of the present
invention;
[0024] FIG. 5B is a top plan view of the assembled panels of the
air bag of FIG. 5A;
[0025] FIG. 6 is a perspective view of the air bag of FIGS. 5A and
5B in an inflated condition;
[0026] FIG. 7 is a schematic view of an inflated air bag installed
in a vehicle;
[0027] FIG. 8 is a schematic view of an air bag installed in a
vehicle and inflated with a lower compartment expanding over an
interfering object, as viewed through the windshield.
[0028] FIG. 9 is a side sectional view of an inflated air bag
having a baffle according to another embodiment of the present
invention;
[0029] FIG. 10 is a perspective view of the inflated air bag of
FIG. 9;
[0030] FIG. 11 is a top plan view of the unassembled components
forming the air bag of FIG. 9;
[0031] FIG. 12A is a top plan view illustrating the arrangement of
components during a portion of the fabrication of the air bag of
FIG. 9;
[0032] FIG. 12B is a sectional view taken along the line 12B-12B of
FIG. 12A;
[0033] FIG. 13A is a top plan view illustrating the arrangement of
components during a step following the step shown in FIGS. 12A and
12B;
[0034] FIG. 13B is a sectional view taken along the line 13B-13B of
FIG. 13A;
[0035] FIGS. 14A to 14D are top plan views illustrating further
fabrication steps following the step shown in FIGS. 13A and 13B;
and
[0036] FIG. 15 is a schematic view illustrating the process of
inflation of the air bag of FIG. 9 installed in a motor
vehicle.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0037] An air bag 50 in accordance with an embodiment of the
present invention will be described with reference to FIGS. 2A, 2B,
3 and 4. Some of the reference numerals used in FIGS. 1A and 1B are
used again to denote like parts, and no description thereof is
repeated.
[0038] The air bag 50 is essentially composed of a main panel 36
having an air inlet 15 and a subpanel 38. The main panel 36 and the
subpanel 38 are both formed from a wover fabric of polar synthetic
fibers, such as polyester or polyamide fibers. The present
invention, however, is not limited to these materials; rather, it
is contemplated that other materials having similar properties may
be used to form the panels. The main panel 36 has a heat-resistant
or reinforced area around the air inlet 15. More specifically, it
has a reinforcing piece of cloth 40 attached to the fabric by
sewing, or a layer of heat-resisting rubber caused by rubbing to
adhere to it, or both.
[0039] The main panel 36 has a pair of first portions 42 that are
symmetric to each other with respect to a boundary located adjacent
to the air inlet 15. It also has a pair of second portions 44 and
46 extending in opposite directions from the first portions 42,
respectively, and are collectively referred to as a pair 48. Each
first portion 42 has a pair of opposite edges 42a and 42b extending
from the boundary between the first portions 42 to one of the
second portions 44 and 46. The main panel 36 may be formed of a
single sheet of fabric. It is also contemplated that two or three
sheets may be joined together by sewing or other suitable fastening
techniques.
[0040] The main panel 36 has a reduced width at the boundary
between the first portions 42. The width of the first portions 42
increases towards the second portions 44 and 46. Each first portion
42 has two halves that may be symmetric to each other with respect
to the longitudinal centerline L of the main panel 36. Each first
portion 42 has a generally equilateral trapezoid shape. The
trapezoid has an angle .theta. between 30 to 80 degrees. The angle
.theta. is preferably from 50 to 60 degrees, between each of its
oblique sides and the base of the first portion 42. This
arrangement is effective for the formation of a three-dimensional
body having an enlarged end.
[0041] The present invention, however, is not limited to the
above-described arrangement for the first portions 42. Each first
portion 42 may alternatively have the shape of a right-angled
trapezoid, or have a pair of parallel edges 42a and 42b, or a
curved edge or edges 42a and 42b, depending on the desired unfolded
form of the air bag to be made.
[0042] The second portions 44 and 46 differ in shape from each
other, and are a low equilateral trapezoid and a high equilateral
trapezoid. Each has rounded top corners, as shown in FIGS. 2A and
2B. The trapezoid may have an angle of 10 to 75 degrees between
each of its oblique sides and its base for the upper second portion
44, and an angle of 20 to 85 degrees for the lower second portion
46. The second portions 44 and 46, however, do not necessarily need
to differ in shape. It is contemplated that the second portions 44
and 46 may have the same shape. Furthermore, each may be, for
example, rectangular or dome-shaped, depending on the desired
unfolded form of the air bag to be made.
[0043] The subpanel 38 has a shape equal to the combined shape of
the second portions 44 and 46 of the main panel 36, if joined to
each other at the edges 44a and 46a, as shown in FIG. 2B. In other
words, it generally has a shape formed by joining a low equilateral
trapezoid and a high equilateral trapezoid together at their
bases.
[0044] The main panel 36 and the subpanel 38 are fastened along
their edges to form an air bag 50. The main panel 36 and the
subpanel 38 are fastened together by sewing the edges together. The
present invention, however, is not limited to sewing; rather, other
fastening modes are contemplated including but not limited to
bonding using a suitable adhesive, high frequency welding,
ultrasonic welding and heat sealing. The first portions 42 of the
main panel 36 are first joined to each other along the edges 42a
forming a first seam S1 on one side and also along their edges 42b
forming another first seam S1 on the other side to make a hollow
body having an open front end, as shown in FIG. 2B. Then, the
second portions 44 and 46 of the main panel 36 with the edges 44a
and 46a meeting each other are placed on the subpanel 38, and are
joined to it along their adjacent edges 44b, 46b and 38a forming
second seams S2, as shown in FIG. 2B.
[0045] The first seams S1 are formed by the edges 42a and 42b of
each first portion 42 of the main panel 36. The second seams S2 are
formed by the edges 44b and 46b of the second portions 44 and 46
joined to the edge 38a of the subpanel 38. The first and second
seams S1 and S2 do not have any overlapping portions when the
panels 36 and 38 are unfolded. With this arrangement, the air bag
50 in accordance with the present invention can be easily
assembled. There is no need to manually adjust the position of the
panels to prevent overlapping joints. There is, therefore, no
necessity of removing any panel manually to avoid any wrong joining
along the first and second seams S1 and S2. The air bag in
accordance with the present invention is easy to make by an
automatic sewing process including the mechanical feeding of the
work.
[0046] The air bag 50 in accordance with the present invention has
a three-dimensional shape when inflated, as shown in FIG. 3. Prior
to deployment, the air bag 50 is folded for use in a top-mount type
air bag device M mounted on a dashboard 52 in a motor vehicle, as
shown in FIG. 4. The air bag device M is preferably located
adjacent the passenger seat. The air bag device M includes the air
bag 50, an inflator 54 for supplying inflating gas into the air bag
50, a housing 56 for the folded air bag 50 and the inflator 54, and
a cover 58 closing the opening of the housing 56. The cover 58 is
molded as an integral part of the dashboard 52.
[0047] The air bag 50 is folded in a customary way as will be
described below. A plurality of retainers 62 having mounting bolts
60 are placed in the air bag 50 through the air inlet 15, and the
bolts 60 protrude from the air bag 50 through the holes 31 around
the air inlet 15. The air bag 50 is first folded along two
transverse lines to form two folds facing each other above the
center of the air inlet 15, and each fold is folded again along
transverse lines to form a front fold 50a in a zigzag form or a
rear fold 50b in rolled form relative to the dashboard 52 of a
motor vehicle on which the air bag device M will be mounted, as
shown in FIG. 4. The folds are rolled towards the air inlet 15
about longitudinal lines.
[0048] The retainers 62 are held against an annular shoulder 57
formed on the inner wall of the housing 56. The interior of the
housing 56 has an upper portion 56a and a lower portion 56b. The
retainers 62 are second to the housing 56 after the inflator 54 has
been installed in the lower portion 56b. The retainers 62 include
bolts 60 that protrude outwardly through the shoulder 57, which are
secured by a nut 64 against the outer surface of the shoulder 57,
such that the folded air bag 50 is installed in the upper portion
56a of the housing 56. It is contemplated that other suitable
fasteners may be used to secure the air bag 50 within the housing
56.
[0049] The air bag device M is secured to the vehicle body by a
suitable bracket, not shown. Upon sensing of a predetermined amount
of impact on the vehicle by a sensing assembly, not shown, the
inflator 54 is activated to jet out inflating gas through the gas
outlet 54a. The inflating gas flows into the air bag 50 through the
air inlet 15. As the air bag 50 inflates, it pushes the cover 58
open and springs out from the housing 56, as shown in phantom in
FIG. 4, and is unfolded and further inflated to protect the
passenger during impact.
[0050] Referring now to FIGS. 5A, 5B and 6-9, a variation of the
air bag 50 according to another embodiment of the present invention
is disclosed. The air bag in accordance with the present embodiment
includes an airbag opening control assembly for
controlling/restricting the opening of the air bag during
inflation. The air bag 50 includes a tether 66, which causes the
inflated bag to expand in a restricted way. The tether 66 is also
formed from a woven fabric, described above. Upon inflation of the
air bag 50, the tether 66 extends between the base wall below the
air inlet 15 and the front wall 17A, as shown in FIG. 6 in the
vicinity of the maximum width B of the subpanel 38. The tether 66
divides the air bag 50 into upper and lower chambers 50a and
50b.
[0051] The tether 66 has a pair of opposite longitudinal edges
extending along the side walls 20A and 22A, respectively, of the
inflated air bag 50. The tether 66 is shaped to have a larger
spacing between one side wall of the air bag 50 that faces the
exterior of the vehicle, than from the opposing side wall. More
specifically, the tether 66 has a width substantially equal to that
of the inflated air bag 50 along its front wall 17A, and is partly
cut away along a longitudinal edge facing the exterior of the
vehicle, as shown at 66a by hatching with broken lines in FIG. 5A.
If the front wall 17A of the inflated air bag 50 has a maximum
width of 500 mm, the tether 66 may have a width of 150 mm along its
edge secured to the base wall and a width of 400 mm along its edge
secured to the front wall 17A. These dimensions are provided merely
for illustrative purposes. It is contemplated that these sizes may
vary. Both larger and smaller sizes are well within the scope of
the present invention. The tether 66 may be cut away at 66a to
occupy an area of 50% to 80% in the plane in which it extends in
the inflated air bag 50. The tether 66 may fail to divide the upper
and lower chambers 50a and 50b of the air bag 50 effectively if it
occupies only an area smaller than 50%. If the tether occupies an
area over 80%, its cutaway portion 66a may fail to control the flow
of air into the lower chamber 50b effectively. The spacing between
the tether 66 and one of the side walls 20A or 22A is at least two
times greater than the spacing between the tether 66 and the other
of the side walls 20A or 22A. It is preferable that the spacing is
three to five times greater between the tether 66 and the one side
wall. If the spacing between the side wall and the tether is
smaller than two times greater than the other spacing, the tether
may fail to control the flow of air into the lower chamber
effectively. If the spacing is larger than by five times than the
other spacing, the air bag may encounter unfolding difficulties
when inflating.
[0052] The air bag 50 has a pair of vent holes 27 formed in the
side walls 20A and 22A in the lower chamber 50b, as shown in FIG.
6. The vent holes 27 are preferably parallel slots arranged
vertically, or at right angles to the longitudinal axis of the air
bag. Other vent hole configurations including but not limited to
circular holes are considered to be well within the scope of the
present invention. The vent holes may have a short diameter of 50
mm or a longer diameter of 80 mm to 90 mm. It is contemplated that
the size of the vent hole may vary. During the initial unfolding
and inflation operation, the air bag is unfolded and inflated
rapidly without any appreciable widening of the vent holes. At this
time, very high tension acts upon the bag. After further inflation,
and immediately before the air bag 50 contacts an interfering
object (i.e., a passenger), the vent holes are widened by the
expansive force of the bag 50 and exhibit a more effective venting
action so as to reduce the inflating pressure acting upon the bag
and thereby ensure a reduction of any impact load bearing upon the
passenger.
[0053] The air bag 50 including the tether 66 is likewise folded
and incorporated in an air bag device M, as described above. If a
predetermined force of impact bears upon the vehicle, a sensor
assembly, not shown, activates the inflator 54 to supply inflating
gas into the air bag 50 through the air inlet 15 to inflate the air
bag 50. The air bag 50 pushes the cover 58 open and unfolds as
shown by two-dot chain lines, as described earlier.
[0054] As the air bag 50 inflates, it extends rearwardly along the
windshield W until the tether 66 is substantially fully stretched.
The upper chamber 50a is in contact with the windshield W. The
inflating gas G then flows into the lower chamber 50b mainly
through the larger clearance between one of the longitudinal edges
of the tether 66 and the one side wall 20A or 22A so as to inflate
the lower chamber 50b to complete the inflation of the air bag 50,
as shown in FIG. 7.
[0055] If the air bag 50 contacts an interfering object I during
inflation before the tether 66 is fully stretched, the inflating
gas G also flows from the upper chamber 50a of the air bag 50 into
the lower chamber 50b mainly through the larger clearance,
described above, between the tether 66 and the one side wall 20A or
22A. As a result, it is possible to control the inflating pressure
urging the air bag 50 rearwardly and thereby prevent any
undesirably large impact from bearing upon the interfering object
I.
[0056] If the interfering object I is small in height, the air bag
50 extends rearwardly over the interfering object I (e.g., the
passenger's head) until the tether 66 is fully stretched. Then, the
inflating gas G flows into the lower chamber 50b through the
clearance between the tether 66 and the side wall 20A to inflate
it, so that the air bag 50 may extend downwardly, too. As a result,
the lower chamber 50b of the air bag 50 extends downwardly between
the interfering object I, such as the passenger's head, and the
side door D of the vehicle, as shown in FIG. 8 (as viewed through
the windshield), and thereby keeps the interfering object I from
being moved toward the side door, while not exerting any
undesirably heavy load upon it. The air bag 50, however, does not
exert any undesirably large impact upon the interfering object I,
even if it may be situated close to the door, since the air bag 50
is already fully stretched, and the gas flowing back after striking
against its front wall 17A does not have a high inflating pressure
when flowing downwardly.
[0057] An air bag according to another embodiment of the present
invention will now be described in connection with FIGS. 9 to 15.
Like the air bags described above, the air bag 110 is also designed
for use in a top mount type air bag device M mounted on the top
surface 101a of a dashboard 101 for protecting a passenger in a
motor vehicle, as shown in FIG. 15. The air bag 110 includes a bag
body 111 shaped substantially like a triangular prism having an
axis extending transversely of the vehicle when inflated. The air
bag 110 also includes an air control assembly for controlling the
flow of air within the air bag during the inflation operation. The
air control assembly may include a baffle 120 for regulating the
flow of inflating gas G in the air bag 110.
[0058] The bag body 111 has a rectangular gas inlet 112 formed at a
bottom of an end portion facing the front of the vehicle for
admitting inflating gas G. The gas inlet 112 is surrounded by a
plurality of bolt holes 114. The bag body 111 also has a pair of
vent holes 115 for letting out any excess of inflating gas. A
substantially square reinforcing piece of cloth 119 woven from e.g.
polyester or polyamide yarns is attached to the inner surface of
the bag body 111 around the gas inlet 112 and the bolt holes
114.
[0059] The bag body 111 is made by securing together two panels 116
and 117, as shown in FIGS. 11 to 14. The panels are preferably
woven from a material, described above. The first or main panel 116
has two half portions 116a and 116e each shaped substantially like
a regular hexagon, and is constricted along the boundary between
its half portions 116a and 116e, as shown in FIG. 11. The second
panel, or subpanel 117 is shaped substantially like a regular
hexagon. The bag body 111 having a three-dimensional shape can
preferably be formed from the two panels 116 and 117 by a
two-dimensional sewing process. The present invention, however, is
not limited to a sewing process; rather, other fastening techniques
are considered to be well within the scope o the present
invention.
[0060] The baffle 120 is larger in size than the gas inlet 112
along all of its edges so as to cover the gas inlet 112 from inside
the bag body 111, as shown in FIG. 10. When the air bag 110 is
inflated, the baffle 120 has a curved portion 129 arcuately shaped
in longitudinal section and having a concavely curved inner surface
facing the gas inlet 112, as shown in FIG. 9. The baffle 120 is
formed from a panel 120P, which is woven from the materials,
described above. As shown in FIG. 11, the panel 120P has an opening
121 corresponding to the gas inlet 112, an inner edge portion 122
surrounding the opening 121 and a pair of laterally extending
portions 123 and 124 each terminating in an arcuate edge 123a or
124a. The panel 120P has a plurality of holes corresponding to the
bolt holes 114, as shown in FIG. 11. The inner edge portion 122 of
the panel 120P is secured to the bag body 111 around the gas inlet
112 using a suitable fastening mechanism, such as, for example,
sewing thread 118 as shown in FIGS. 12A and 12B. The laterally
extending portions 123 and 124 are secured to each other along
their arcuate edges 123a and 124a, as shown in FIGS. 13A and 13B,
whereby the baffle 120 is formed. The baffle 120 has a varying
distance between a seam joining the portions 123 and 124 to the bag
body 111 around the gas inlet 112 and a seam 125 joining the
arcuate edges 123a and 124a to each other. The distance is longer
at the front end 126 than at the back end 128, and is longer in the
transversely middle portion 127 than at the front end 126. Thus,
the baffle 120 forms a tubular path for inflating gas G having a
varying cross-sectional area. The cross-sectional area SF at the
front end 126 of the baffle 120 is larger than the cross-sectional
area SB at the back end 128, but is smaller than the
cross-sectional area SC in the middle portion 127. The gas inlet
112 has a width B0 of 61 mm, and the laterally extending portions
123 and 124 have a width B1 of 300 mm along their seam 125, while
the seam 125 has a radius R of curvature of 300 mm (see FIG. 12A).
These dimensions are merely provided for illustrative purposes;
other dimensions are considered to be well within the scope of the
present invention.
[0061] The fabrication of the air bag 110 will now be described in
connection with sewing as the preferred fabrication method. Other
methods of fabrication including but not limited to the use of
adhesives and bonding are considered to be well within the scope of
the present invention. Referring now to the fabrication of the air
bag 110, the reinforcing cloth 119 and the baffle panel 120P are
first fastened with sewing thread 118 to the main panel 116 along
the edge 113 of the gas inlet 112 on the surface defining the inner
surface of the air bag 110, as shown in FIGS. 11, 12A and 12B. The
laterally extending portions 123 and 124 of the panel 120P are
fastened to each other along their edges 123a and 124a with sewing
thread 118 to form an arcuate seam to define an appropriate shape
for the baffle 120, as shown in FIGS. 13A and 13B. The baffle 120
may have at least one vent hole V for controlling the inflation of
the air bag, as shown in FIG. 12B.
[0062] The main panel 116 is folded along a first reference line L1
extending transversely between the upper and lower half portions
116a and 116e, and the half portions 116a and 116e are fastened to
each other with sewing thread 118 along the adjoining straight
edges 116b and 116f on one side of the gas inlet 112 and also along
the adjoining straight edges 116c and 116g on the opposite side
thereof, as shown in FIGS. 14A and 14B.
[0063] The upper half portion 116a of the main panel 116 is folded
along a second reference line L2 extending along the largest width,
so that the half portions 116a and 116e respectively, may extend in
a plane, as shown in FIGS. 14B and 14C. The free edges 116d and
116h are so shaped to lie in a plane and define a contour
coinciding with the subpanel 117, as is obvious from FIG. 14C.
Therefore, the subpanel 117 is properly placed on the main panel
116 folded as described, and the two panels 116 and 117 are sewn to
each other along their coinciding edges to form a shape defining
the bag body 111, as shown in FIG. 14D.
[0064] The bag body 111, as formed, is reversed so that no margin
left for sewing may be exposed on the air bag 110. The bag body is
reversed by pulling an inner surface through the gas inlet 112. If
it is difficult to reverse in such a way, it is alternatively
possible to pull out the laterally extending portions 123 and 124
of the baffle panel 120P and fasten them to each other along their
edges 123a and 124a after reversing the bag body 111.
[0065] The air bag 110 is installed in a motor vehicle in the
manner, described above in connection with airbag 50 as described
before, and as shown in FIG. 15. It is advisable to enclose the air
bag 110 in a wrapping sheet 132 to keep it in a good folded shape,
though it is not essential to do so. During inflation, the air bag
110 breaks the wrapping sheet 132, and protrudes in a largely
inflated shape from the upper portion 137 of the housing 136 after
tearing open the cover 147 along a tearing line 148b between two
portions 148a, as shown in FIG. 15.
[0066] The gas G entering the air bag 110 through the inlet 112 is
divided by the baffle 120 into a gas stream GF flowing forward in
the bag and a gas stream GB flowing backward, as shown in FIGS. 9
and 13B. The gas G flowing into the air bag body 111 through the
gas inlet 112 strikes against the arcuately curved portion 129 of
the baffle 120 and is thereby deflected to flow along the curved
inner surface of the baffle toward the top surface 101a of the
dashboard 101 instead of flowing in parallel to the latter, while
inflating the bag body 111. As a result, the bag body 111 is likely
to extend backwardly from the top surface 101a of the dashboard 101
to the back surface 101b, as shown by two-dot chain lines in FIG.
15.
[0067] The baffle 120 can be formed from only a small amount of
material. It has only to be formed with a portion having a
concavely curved surface facing the gas inlet 112. Nevertheless, it
enables the air bag 110 to extend backwardly along the surfaces
101a and 101b of the dashboard 101 during the initial stage of
inflation.
[0068] The baffle 120 has a middle portion 127 situated somewhat
behind the center of the gas inlet 112 to promote the flow of a
backward stream of inflating gas GB from the top surface 101a of
the dashboard 101 to the back surface 101b. As such, the lower
portion 110b of the air bag 110 extends along the surfaces of the
dashboard 101. Since the cross-sectional area SF of the baffle 120
at the front end 126 is larger than the cross-sectional area SB at
the back end 128, the stream of inflating gas GF flowing forward in
the bag is larger than the stream GB flowing backward. As such, the
upper portion 110a of the air bag 110 inflates more quickly so that
the portion 110c facing the passenger may quickly inflate. The
upright portion 110c has a broad area of contact with the passenger
such that only a low pressure per unit area may bear upon the
passenger.
[0069] The arcuately curved portion 129 of the baffle 120 facing
the gas inlet 112 of the bag body 111 can be easily formed. If the
laterally extending portions 123 and 124 of the panel 120P are sewn
to each other along the edges 123a and 124a, after the portion 122
around the opening 121 is fastened to the edge 113 of the inlet
112. Thus, the baffle 120 is easy to form in the bag body 111. The
baffle 120 may also be formed if a strip of material extending
transversely of a vehicle has its side edges sewn, or otherwise
fastened to an air bag along a pair of edges of the inlet 112. The
baffle has an appropriately curved portion extending longitudinally
of the vehicle and facing the inlet 112 if its front and back edges
are appropriately tucked.
[0070] Other baffle arrangements are contemplated. The baffle panel
120P may alternatively be composed of two pieces of material, i.e.,
one forming the edge portion 122 around the opening 121 and one of
the laterally extending portions 123 and the other forming the edge
portion 122 and the other laterally extending portion 124, which
are sewn, or otherwise fastened to the main panel 116 around the
edge 113 of the gas inlet 112 before they are joined to each other
along edges 123a and 124a. It will be sufficient for only either of
those two pieces of material, or even neither, to be so shaped as
to form the edge portion 122, if a suitable reinforcing piece of
cloth is employed.
[0071] While this invention has been described in conjunction with
specific embodiments thereof, it is evident that many alternatives,
modifications, variations and combination of elements will be
apparent to those skilled in the art. For example, the invention
has been described by its embodiments directed to three-dimensional
air bags, it is also applicable to a planar air bag having its body
formed by two panels situated on the inflator 34 and passenger
sides, respectively, and sewn, or otherwise joined to each other
along their edges. The preferred embodiments of the invention as
set forth herein are intended to be illustrative, not limiting.
Various changes may be made without departing from the spirit and
scope of the invention as defined in the following claims.
* * * * *