Land vehicles – Wheeled – Attachment
Reexamination Certificate
2000-02-08
2001-09-04
Dickson, Paul N. (Department: 3618)
Land vehicles
Wheeled
Attachment
C280S743100
Reexamination Certificate
active
06283502
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an air bag apparatus adapted for an automotive vehicle, and particularly to one which is assembled to a steering wheel.
2. Description of Relevant Art
Generally, in an air bag apparatus for an automotive vehicle, an air bag module is assembled at a central portion of a steering wheel. An air bag module accommodates a folded air bag and an inflator inside a casing. When an automotive vehicle is collided, the air bag is expanded by a gas which is generated by an inflator. The air bag pushes the cover to be broken and develops to outside. Further, the air bag receives an occupant who falls to a side of the steering wheel, thereby to protect him.
In a conventional art, as known in Japanese Patent Application Laid-open No. 9-295546, an air bag is shifted on an upper side to be developed so that an upper portion and a lower portion of the air bag can simultaneously contact with an occupant.
SUMMARY OF THE INVENTION
However, in such a conventional art, an air bag is structured such that it is shifted to an upper side to be developed, and there is possibility a lower end of a rim in a steering wheel is not covered with a lower portion of the air bag. Therefore, if only the lower end of the rim has a strength to easily transform, manufacturing a steering wheel is troublesome and is disadvantageous in view of cost.
It is an object of the invention to provide an air bag apparatus in which an air bag covers a whole steering wheel and an upper portion and a lower portion of an air bag simultaneously contact with an occupant at an early stage of development.
To achieve the object, an air bag apparatus for an automotive vehicle is provided with members as follows. A casing is fixed to a steering wheel, and has a first center line, an upper space and a lower space. The first center line is positioned below a second center line of the steering wheel. An inflator is arranged in the casing and has a third center line. The inflator is for generating a gas. The third center line is positioned below the first center line and positioned at a boundary between the upper space and the lower space. An air bag has an upper portion accommodated in the upper space and a lower portion accommodated in the lower space. The upper portion is in an upper folding state. The lower portion is in a lower folding state. The upper folding state is looser than the lower folding state.
The word, “folding state”, means intervals between folds of an air bag. The word, “loose”, means that the intervals are large and the word, “dense”, means that the intervals are small. The word “loose” is looser than “dense”.
Preferably, the upper portion has an upper volume, the lower portion has a lower volume, and the upper volume is approximately equal to the lower volume.
Preferably, the air bag apparatus further has a cover which is fixed to the casing and has a breaking portion to be broken to open by the gas from the inflator. The breaking portion is positioned above the first center line.
Preferably, the breaking portion is thinner than other portions of the cover.
Preferably, the breaking portion has a recess on an inside of the cover.
Preferably, the air bag has a fourth center, and the fourth center is positioned on or below the third center line of the inflator.
Herein, the first center line passes a geometrical center of the casing. The second center line passes a geometric center of the steering wheel and is along an axis direction of a steering shaft. The third center line passes a geometric center of the inflator. The fourth center is a geometric center of the air bag.
According to the invention, a third center line of an inflator is positioned below a first center line of a casing, and an upper space above an inflator is larger than a lower space. An upper portion is accommodated in the upper space of the casing, while a lower portion is accommodated in the lower space of the casing. An upper folding state of an upper portion is looser than a lower folding state. Therefore, the upper portion accommodated in the upper space is developed earlier than the lower portion accommodated in the lower space. Namely, a gas enters into folds with large intervals more easily than those with small intervals. Further, a gas generated by the inflator is discharged to a large upper space more than a small lower space in a closed system. Thus, in a case of accommodating an air bag in the large upper and small lower spaces, an upper portion of the air bag accommodated in the large upper space is developed earlier than a lower portion of the air bag. As a result, first contact phenomenon that the lower portion is first brought in contact with an occupant is corrected, the first contact being caused by arranging an air bag module below. If an occupant have attitude to sit significantly close to a front side, the upper and lower portions of the air bag simultaneously contact with an occupant at an early stage of development of the air bag, thereby to evenly protect a head portion and a body portion of the occupant.
Further, a breaking portion of a cover is positioned above a first center line of a casing, and an upper side cover above the breaking portion is smaller than a lower side cover. As a result, when an air bag expands in a casing to lift a cover, an opening angle of the upper side cover is larger than that of a lower side cover. Therefore, when the cover is separated into upper and lower portions, the upper side cover has already opened at a large angle with a small size, so that the upper side cover opens earlier than the lower side cover. An upper portion of the air bag early develops from the upper side cover early opened. Further, the delayed opened lower side cover guides the air bag to an upper side. As a result, first contacting a lower portion of the air bag in contact with an occupant is better corrected, and a head portion and a body portion of an occupant evenly protected.
Further, breaking portion is thin formed from inside of a cover, and it does not appear on outside of the cover, thereby being excellent in view of outward appearance.
REFERENCES:
patent: 4752083 (1988-06-01), Honda
patent: 5887892 (1999-03-01), Burdack et al.
patent: 5897133 (1999-04-01), Papandreou
patent: 09295546 (1997-11-01), None
Endo Tetsuji
Yanagidaira Kazuo
Dickson Paul N.
Fleming Faye M.
Kilpatrick & Stockton LLP
Nihon Plast Co. Ltd.
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