Land vehicles – Wheeled – Attachment
Reexamination Certificate
2001-02-27
2002-10-08
English, Peter C. (Department: 3616)
Land vehicles
Wheeled
Attachment
C280S730200
Reexamination Certificate
active
06460877
ABSTRACT:
BACKGROUND OF THE INVENTION
The present application claims priority to Japanese patent application of Tanabe et al., filed Mar. 23, 2000, No. 2000-081908, and Japanese patent application of Tanabe et al., filed Mar. 30, 2000, No. 2000-094708.
1. Field of the Invention
The invention relates to an airbag for use in a head protective airbag device mounted on a roof-side rail section of a motor car, an airbag device for lateral collision and mounted on a seat, and the like.
2. Description of Related Art
Conventionally, for example, with a head protective airbag device, an airbag is folded and received to extend over a door and a peripheral edge of an opening on windows on a vehicle-interior side. When an expansion gas inflows, the airbag is developed and expanded in a manner to cover the opening. The airbag is provided with an expansion section, which allows an expansion gas to inflow to thereby expand in a manner to separate a vehicle-interior side wall and a vehicle-exterior side wall from each other.
A plurality of linear connections are arranged in a region of the expansion section (see Japanese Patent Laid-Open No. 321535/1999). The linear connections join opposite portions of peripheral walls, which constitute the expansion section, to one another in a linear fashion. Such linear connections are arranged in order to make peripheral edges and a central portion of the expansion section substantially uniform in thickness. Further, with a head protective airbag device, the linear connections are arranged to make an airbag exert tensile forces in a longitudinal direction to prevent the airbag from moving outside the vehicle even when the airbag is subjected to pushing forces toward the outside of the vehicle.
However, if end portions of the linear connections are small in area, stress concentration is liable to occur on the end portions of-the linear connections at the time of expansion of the expansion section. Thus if the end portions are small in area, peripheral walls, which constitute the expansion section in the vicinity of the end portions, are in some cases broken.
Therefore, the linear connections including the end portions are arranged in a wide dimension.
However, if all the linear connections including the end portions are arranged in a wide dimension, a volume of the expansion section, into which an expansion gas is caused to flow, and an expansion area decrease. That is, when the linear connections are formed to be wide, the cushioning quality of an airbag is influenced thereby.
SUMMARY OF THE INVENTION
There is a need to solve the above-mentioned problems and to provide an airbag capable of arranging linear connections without causing breakage of peripheral walls at the time of development and expansion, while holding down reduction of a volume and an expansion area.
Accordingly, an embodiment of the present invention provides an airbag comprising an expansion part permitting an expansion gas to inflow to expand a peripheral wall, and linear joining portions arranged in a region of the expansion part and constituted by joining facing portions of the peripheral wall in a linear manner. The linear joining portions comprise a base, curved portions and swelling portions. The base is arranged to be substantially linear. Each of the curved portions is connected to a respective base and curvilinearly extends from the respective base thereof. The swelling portions are arranged at tip ends of the curved portions to smoothly connect outer peripheral edges thereof to outer peripheral edges of the curved portions. And the linear joining portions are arranged in accordance with B
0
<R
2
<R
1
is established where B
0
is a widthwise dimension near portions of the base connected to the curved portions, R
1
is a radius of curvature of the outer peripheral edges of the curved portions, and R
2
is a radius of curvature of the outer peripheral edges of the swelling portions.
With the airbag according to the invention, end portions of the linear joining portions are formed in a manner to be made contiguous to the swelling portions through the curved portions from the substantially straight base. And the swelling portions connect outer peripheral edges thereof smoothly to the outer peripheral edges of the curved portions, and the outer peripheral edges of the swelling portions have a radius R
2
of curvature greater than a width dimension BO of the base. Therefore, stress concentration is reduced around the swelling portions when the expansion portions expand.
Also, the outer peripheral edges of the curved portions have a radius R
1
of curvature larger than the radius R
2
of curvature of the outer peripheral edges of the swelling portions. Therefore, stress concentration is reduced around the curved portions.
At the end portions of the linear joining portions, the swelling portions are made wide. However, inner peripheral edges of the curved portions, which connect the base and the swelling portions, are recessed to enable making small the curved portions and the base. Therefore, reduction in volume of the expansion portions can be held down as much as possible.
Accordingly, with the airbag according to the invention, the linear joining portions can be arranged without causing breakage of the peripheral wall at the time of development and expansion and with reduction in volume and expansion area held down as much as possible.
And it is desired that the portions of the base near the curved portions are arranged substantially in parallel to a main flow of the inflowing expansion gas, and the swelling portions are arranged offset from the base in directions substantially perpendicular to the main flow of the expansion gas.
With such constitution, the swelling portions do not directly interfere with a main flow of an expansion gas, and stress concentration can be reduced around the swelling portions. Therefore, it becomes possible to reduce an area of the linear joining portions as well as an area of the swelling portions on the end portions. And it becomes possible to further increase a volume and expansion area of the airbag.
Also, the swelling portions may be arranged offset from the base toward branching flow passages branching from the main flow passage, through which the main flow of the expansion gas flows.
With such constitution, the swelling portions do not further interfere with a main flow of an expansion gas, and stress concentration can be reduced around the swelling portions. Therefore, in this case, it becomes possible to reduce an area of the linear joining portions as well as an area of the swelling portions on the end portions. That is, it becomes possible to increase a volume and expansion area of the airbag.
Further, in the case where the airbag is formed by hollow-weaving, it is desired that a radius of curvature R
1
of the outer peripheral edges of the curved portions is in the range of 15 to 100 mm, and a radius of curvature R
2
of the outer peripheral edges of the swelling portions is in the range of 10 to 15 mm.
With an airbag constituted in such manner, the linear joining portions can be arranged with reduction in volume and expansion area held down as much as possible.
Incidentally, the radius R
1
of curvature of the outer peripheral edges of the curved portions are below 15 mm, stress concentration is liable to occur around the curved portions at the time of expansion of the expansion part to cause the possibility of breakage of the peripheral wall at the time of expansion and development of the airbag. Also, when the radius R
1
of curvature exceeds 100 mm, the degree of bending from the base decreases, so that the main flow of the expansion gas becomes liable to interfere with the swelling portions. And it is not preferable to lengthen the curved portions so as to avoid this, since the airbag is made small in volume and expansion area.
Also, the radius R
2
of curvature of the outer peripheral edges of the swelling portions are below 10 mm, stress concentration is liable to occur around the swelling portions at the time of expansion of the expan
Ishii Mikihito
Nakamura Eisiti
Takei Yoshinari
Tanabe Choko
Tanase Toshinori
English Peter C.
Toyoda Goseki Co., Ltd.
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