Tuck folded air bag

An air bag (10) comprises an elongate panel (20) having first and second longitudinally extending side portions (40,50) and a longitudinally extending central portion (60). The panel (20) has first and second opposite end portions (70,80). A first side seam (102) extends along the first side portion (40) of the panel (20). A second side seam (104) extends along the second side portion (50) of the panel (20). A transverse seam (100) joins the first end portion (70) of the panel (20) to the second end portion (80) of the panel. The seams (100, 102, 104) provide the air bag (10) with a pillow-shaped configuration when inflated. The first side portion (40) of the panel (20) is tucked inside the central portion (60) of the panel and is sewn to the central portion with a first tearable stitching section (110) when the air bag (10) is in the deflated condition. The first tearable stitching section (110) is tearable in response to the application of a force greater than a predetermined force due to inflation of the air bag (10) to enable movement of the first side portion (40) from the tucked position to an inflated position extending laterally outward from the central portion (60).

BACKGROUND OF THE INVENTION 
1. Technical Field 
The present invention relates to an inflatable vehicle occupant protection 
device, and is particularly directed to an air bag for helping to protect 
a vehicle occupant in the event of a vehicle collision. 
2. Description of the Prior Art 
It is known to inflate an air bag to help protect a vehicle occupant in the 
event of an impact to a vehicle of a magnitude above a predetermined 
threshold. The air bag is stored in a deflated condition, together with an 
inflator, in a portion of the vehicle such as the instrument panel. In the 
event of an impact to the vehicle of a magnitude above the predetermined 
threshold, the inflator is actuated, and the air bag is inflated into a 
position adjacent to the vehicle occupant. The air bag can help to protect 
the vehicle occupant from forcefully striking or being struck by parts of 
the vehicle. 
An air bag which inflates from an instrument panel of a vehicle typically 
expands both vertically and laterally as it moves from the deflated 
condition to the inflated condition. It may be desirable that the air bag 
inflate vertically as quickly as possible, prior to inflating laterally, 
to help to protect an out of position vehicle occupant. 
SUMMARY OF THE INVENTION 
The present invention is an inflatable vehicle occupant protection device 
for helping to protect an occupant of a vehicle. The protection device is 
inflatable from a deflated condition to an inflated, occupant protecting 
condition by inflation fluid from an inflation fluid source. The 
protection device comprises an elongate panel of material having first and 
second longitudinally extending side portions and a longitudinally 
extending central portion extending between the first and second side 
portions. The panel has first and second opposite end portions. The 
protection device includes a first side seam extending along the first 
side portion of the panel, a second side seam extending along the second 
side portion of the panel, and means for joining the first end portion of 
the panel to the second end portion of the panel. The protection device 
has a pillow-shaped configuration when inflated. 
The first side portion of the panel is tucked inside the central portion of 
the panel and is sewn to the central portion with a first tearable 
stitching section when the inflatable device is in the deflated condition. 
The first tearable stitching section is tearable in response to the 
application of a force greater than a predetermined force due to inflation 
of the protection device to enable movement of the first side portion of 
the panel from the tucked position to an inflated position extending 
laterally outward from the central portion.

DESCRIPTION OF PREFERRED EMBODIMENT 
The present invention relates to an inflatable vehicle occupant protection 
device, and is particularly directed to a protection device for helping to 
protect a vehicle occupant in the event of a vehicle collision. As 
representative of the present invention, FIG. 1 illustrates a specific 
inflatable vehicle occupant protection device 10 of the type commonly 
known as an "air bag". The air bag 10 is illustrated as being inflatable 
from an instrument panel 12 of a vehicle 14 to help protect an occupant of 
the vehicle from contact with parts of the vehicle. The air bag 10 is a 
"pillow" type air bag which is mounted in the vehicle 14 in a mid-mount 
configuration. It should be understood that the present invention is 
applicable to other air bag and mounting configurations as well. 
The air bag 10 is made from a single panel 20 (FIG. 2) of fabric material, 
preferably woven nylon, which is folded and sewn to form the air bag. The 
panel 20 (FIG. 2) has a longitudinal central axis 22. A transverse axis 24 
of the panel 20 extends perpendicular to the longitudinal axis 22. The 
panel 20 has an inner major side surface 26 (FIG. 2) and an opposite outer 
major side surface 28 (FIG. 3) 
The panel 20 is generally rectangular in configuration including first and 
second opposite side edges 30 and 32 which extend parallel to the 
longitudinal axis 22. The panel 20 also has first and second opposite end 
edges 34 and 36 which extend between and interconnect the side edges 30 
and 32. 
The panel 20 has a longitudinally extending first side portion 40. The 
first side portion 40 of the panel 20 is defined by the first side edge 30 
and an imaginary line 42 which extends parallel to the first side edge at 
a location between the first side edge and the longitudinal axis 22. A 
longitudinally extending second side portion 50 of the panel 20 is defined 
by the second side edge 32 and an imaginary line 52 which extends parallel 
to the second side edge at a location between the second side edge and the 
longitudinal central axis 22. A longitudinally extending central portion 
60 of the panel 20 is disposed between the first and second side portions 
40 and 50, that is, between the imaginary lines 42 and 52. 
The panel 20 has a first end portion 70 which includes the first end edge 
34 of the panel. An elongate inflation fluid opening 72 is formed in the 
first end portion 70 of the panel 20, at a location adjacent to the first 
end edge 34. A second end portion 80 of the panel includes the second end 
edge 36 of the panel. An elongate inflation fluid opening 82 is formed in 
the second end portion 80 of the panel 20, at a location adjacent to the 
second end edge 36. 
The inflation fluid opening 82 in the second end portion 80 of the panel 20 
is identical in configuration to the inflation fluid opening 72 in the 
first end portion 70 of the panel. The inflation fluid openings 72 and 82 
are centered on the longitudinal axis 22 of the panel 20. The inflation 
fluid openings 72 and 82 communicate with an inflation fluid volume 84 
(FIG. 8) which is formed when the panel 20 is folded and sewn to make the 
air bag 10. 
The inner major side surface 26 (FIG. 2) of the panel 20 includes a first 
section 90 on the first side portion 40 of the panel. A second section 92 
of the inner major side surface 26 of the panel 20 is disposed on an 
adjacent part of the central portion 60 of the panel. The inner major side 
surface 26 also includes a third section 94 on the second side portion 50 
of the panel 20. A fourth section 96 of the inner major side surface 26 of 
the panel 20 is disposed on an adjacent part of the central portion 60 of 
the panel 20. 
The panel 20 is initially folded as seen in FIG. 4, with the inner side 
surface 26 on the outside, so that the first end portion 70 of the panel 
20 overlies the second end portion 80. The inflation fluid opening 72 in 
the first end portion 70 of the panel 20 is aligned with and overlies the 
inflation fluid opening 82 in the second end portion 80 of the panel. A 
transverse seam 100 joins the first end portion 70 of the panel 20 to the 
second end portion 80 of the panel. 
The panel 20 is also sewn along its side edges with first and second side 
seams 102 and 104. The first side seam 102 extends along the first side 
portion 40 of the panel 20. The second side seam 104 extends along the 
second side portion 50 of the panel 20. The air bag 10 as thus sewn has a 
pillow-shaped configuration when inflated. 
The sewn air bag 10 is then inverted or turned "right side out" (FIG. 6) so 
that the outer side surface 28 of the panel 20 is on the outside of the 
air bag. The seam allowance at the first and second side seams 102 and 104 
is disposed inside the inflation fluid volume 84. 
After the air bag 10 is inverted, the first side portion 40 of the panel 20 
is tucked inside the central portion 60 of the panel, in a direction 
toward the longitudinal central axis 22, as shown schematically in FIG. 6. 
In other words, the first side portion 40 is tucked between the overlying 
layers of the central portion 60 with the side portion 40 disposed in two 
layers. The first side portion 40 is tucked in far enough to reduce the 
width of the air bag 10 significantly. The first side edge 30 of the panel 
20 forms a laterally inward (from left to right as viewed in FIGS. 6-9) 
edge of the tucked first side portion 40 of the panel. 
The first side portion 40 of the panel 20 is sewn to the central portion 60 
of the panel with a first tearable stitching section 110. The first 
tearable stitching section 110 has a C-shaped configuration (FIG. 7) 
including a base portion 112 which extends parallel to the first side seam 
102. The base portion 112 of the first tearable stitching section 110 is 
disposed adjacent to the laterally inward edge 30 of the tucked first side 
portion 40 of the panel 20. The first side seam 102 is disposed 
intermediate the first tearable stitching section 110 and the laterally 
inward edge 30 of the tucked first side portion 40. 
The C-shaped configuration of the first tearable stitching section 110 also 
includes a first arm portion 114 which extends laterally outward from the 
base portion 112, in a direction toward the outer side edge 116 of the 
tucked first side portion 40 of the panel 20. A second arm portion 118 of 
the first tearable stitching section 110 extends laterally outward from 
the base portion 112, in a direction toward the outer side edge 116 of the 
tucked first side portion 40 of the panel 20. 
The first tearable stitching section 110 comprises a plurality of stitches 
which extend through the first side portion 40 of the panel and through 
the central portion 60 of the panel. The plurality of stitches extend from 
the outer major side surface 28 (FIG. 6) on the first side portion 40 of 
the panel 20, through the abutting first and second sections 90 and 92 of 
the inner major side surface 26 of the panel, and through the outer major 
side surface 28 on the adjacent part of the central portion 60 of the 
panel. The stitches only extend through one layer of the first side 
portion 40 of the panel 20, not both layers. 
The second side portion 50 of the panel 20 is also tucked inside the 
central portion of the panel, in a direction toward the longitudinal 
central axis 22, as shown schematically in FIG. 6. In other words, the 
first side portion 40 is tucked between the overlying layers of the 
central portion 60 with the side portion 40 disposed in two layers. The 
second side portion 50 is tucked in far enough to reduce the width of the 
air bag 10 significantly. The second side edge 32 of the panel 20 forms a 
laterally inward (from right to left as viewed in FIGS. 6-9) edge of the 
tucked second side portion 50 of the panel. 
The second side portion 50 of the panel 20 is sewn to the central portion 
60 of the panel with a second tearable stitching section 120. The second 
tearable stitching section 120 has a C-shaped configuration (FIG. 7) 
including a base portion 122 which extends parallel to the second side 
seam 104. The base portion 122 of the second tearable stitching section 
120 is disposed adjacent to the laterally inward edge 32 of the tucked 
second side portion 50 of the panel 20. The second side seam 104 is 
disposed intermediate the second tearable stitching section 120 and the 
laterally inward edge 32 of the tucked second side portion 50. 
The C-shaped configuration of the second tearable stitching section 120 
also includes a first arm portion 124 which extends laterally outward from 
the base portion 122, in a direction toward the outer side edge 126 of the 
tucked second side portion 50 of the panel 20. A second arm portion 128 of 
the second tearable stitching section 120 extends laterally outward from 
the base portion 122, in a direction toward the outer side edge 126 of the 
tucked second side portion 50 of the panel 20. 
The second tearable stitching section 120 comprises a plurality of stitches 
which extend through the second side portion 50 of the panel 20 and 
through the central portion 60 of the panel. The plurality of stitches 
extend from the outer major side surface 28 on the second side portion 50 
of the panel 20, through the abutting third and fourth sections 94 and 96 
of the inner major side surface 26 of the panel, and through the outer 
major side surface 28 on the adjacent part of the central portion 60 of 
the panel. The stitches only extend through one layer of the second side 
portion 50 of the panel 20, not both layers. 
The stitches which form the first and second tearable stitching sections 
110 and 120 are tearable in response to the application of a force greater 
than a predetermined force. The predetermined force, as described below, 
is exceeded at a time when the air bag 10 is partially but not yet fully 
inflated. 
A tubular attachment panel 140 (FIG. 6) is sewn to the panel 20 in a known 
manner with a stitching section 142. The assembled air bag 10 is 
thereafter folded in a known manner (not shown) and mounted in the 
instrument panel 12 of the vehicle 14 as a portion of an air bag module 
indicated schematically at 150. The module 150 includes, in addition to 
the air bag 10, an inflator indicated schematically at 152. The inflator 
152 is connected by lead wires 154 with known electric circuitry of the 
vehicle indicated schematically at 156 which includes a power such source, 
such as the vehicle battery, and a collision sensor. 
In the event of a vehicle collision of a magnitude for which inflation of 
the air bag 10 is desired to help protect the vehicle occupant, the 
vehicle electric circuitry 156 causes electric current to be supplied over 
the lead wires 154 to the inflator 152. The inflator 152 is actuated in a 
known manner and directs inflation fluid under pressure into the air bag 
10. The air bag 10 inflates from a folded, stored condition to an inflated 
condition in the manner illustrated schematically in FIGS. 8 and 9. 
The air bag 10 inflates in a direction away from the inflation fluid 
openings 72 and 82, vertically as illustrated in FIG. 8, and assumes a 
partially inflated condition, as shown in FIG. 8. The pressure of the 
inflation fluid in the air bag 10 is transmitted into the first and second 
tearable stitching sections 110 and 120. Initially, the force on the 
tearable stitching sections 110 and 120 is not greater than the 
predetermined force. That is, the resistance to tearing of the first and 
second tearable stitching sections 110 and 120 is sufficient to maintain 
the side portions 40 and 50 of the air bag 10 sewn to the central portion 
60 of the air bag until the air bag is inflated vertically. 
After the air bag 10 is inflated vertically to the extent shown in FIG. 8, 
the force of the inflation fluid in the air bag, applied to the first and 
second tearable stitching sections 110 and 120, exceeds the predetermined 
force. The stitches of the first and second tearable stitching sections 
110 and 120 tear. 
When the first tearable stitching section 110 tears, the first side portion 
40 of the air bag 10 is released for movement relative to the central 
portion 60 of the air bag. The first side portion 40 of the air bag then 
inflates laterally outward as illustrated in FIG. 9, in a direction that 
is generally perpendicular to the direction in which the air bag 10 
initially inflates. When the second tearable stitching section 120 tears, 
the second side portion 50 of the air bag 10 is released for movement 
relative to the central portion 60 of the air bag. The second side portion 
50 of the air bag 10 then inflates laterally outward as illustrated in 
FIG. 9. The air bag 10 assumes a fully inflated condition. 
In one exemplary air bag 10 which has been constructed in accordance with 
the present invention, the air bag has a width, when laid flat, of about 
1,000 to 1,100 millimeters between the first side seam 102 and the second 
side seam 104. The exemplary air bag 10 has one side portion tucked in 160 
mm. That is, the distance between the outermost edge of the tucked air 
bag, and the side seam, is 160 mm. The other side portion of the exemplary 
air bag is tucked in 110 mm. 
From the above description of the invention, those skilled in the art will 
perceive improvements, changes and modifications in the invention. For 
example, the panel 20 may be pleated at the top and bottom prior to 
tucking in the side portions. The stitching sections can be single needle 
or double needle as appropriate. Also, the tearable stitching sections can 
extend through the multiple layers of the seam allowance on the tucked 
side portions of the bag, rather than through only a single layer of the 
tucked side portions as shown in the drawings. Such improvements, changes 
and modifications within the skill of the art are intended to be covered 
by the appended claims.