Land vehicles – Wheeled – Attachment
Reexamination Certificate
2000-10-12
2002-07-23
Mai, Lanna (Department: 3619)
Land vehicles
Wheeled
Attachment
C280S731000, C280S728200, C280S728300
Reexamination Certificate
active
06422602
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of Invention
The present invention relates to an air bag in air bag system installed in an automotive steering wheel and an instrument panel in front of the passenger seat.
The present application is based on Japanese Patent Applications No. Hei. 11-292984 and 2000-070620, which are incorporated herein by reference.
2. Description of the Related Art
There is a known an air bag system installed in a steering wheel as disclosed in JP-A-10-175494, for example, the air bag being folded up and housed in a casing.
More specifically, a peripheral wall portion on a side opposite to an opening for introducing an inflation gas is put on the side of a peripheral wall portion having the opening in such a manner as to set flatly developed peripheral edges closer to the opening side before being folded twice.
The folding at the first stage comprises the steps of forming a lateral crease, and putting the longitudinal edges of flatly developed peripheral edges on a side opposite to an opening under a bellows folding method so that the edges may be set closer to the opening.
The folding at the second stage further comprises the steps of forming a longitudinal crease, and folding the peripheral edges on the two lateral end portions around the opening under an outer roll folding method for winding the peripheral edges so that the edges may be set closer to the opening.
The air bag thus folded up at the two stages is fitted to the bag holder of a casing including the bag holder and an air bag cover (pad). Then the pad is coupled to the bag holder whereby to house the air bag in the casing.
An inflator for supplying an inflation gas to the air bag is simultaneously incorporated in the air bag system when the air bag is housed in the casing to complete the assembly work. Moreover, the air bag system utilizes the casing (bag holder) for being fitted to the steering wheel body coupled to the steering shaft of a vehicle whereby to assemble and mount the air bag system on the vehicle.
In the case of such a conventional air bag, however, the peripheral wall portion on the side opposite to the opening is put on the side of the peripheral wall portion having the opening for introducing the inflation gas to form a flatly developed air bag. Then the air bag is halved and folded up at the first stage and further the laterally long folded regions are again folded up at the second stage. The flatly developed air bag is ultimately folded into two packs and the problem is that finished air bag tends to become thicker.
In order to reduce the thickness of the air bag system as disclosed in JP-A-10-175494, the two packs thus folded up at the second stage have been distributed to the respective spaces on both sides of the inflator for supplying the inflation gas to the air bag.
Notwithstanding, though the distribution of the folded packs to the respective spaces of the inflator may result in reducing the thickness of the air bag, the shape of the folded air bag as viewed from above becomes larger and this makes it difficult to house the air bag in a compact casing.
Moreover, the region where the air bag is folded is disposed in the vicinity of the outer peripheral edge apart from the center of the inflator and the pack of the folded air bag is not disposed between the air bag cover region used to substantially cover the center of the folded air bag and the inflator, so that there existed a space therebetween. When a horn switch is turned on by holding down the air bag cover, the above region of the air bag cover may yield to the pressure in a case where the center of the air bag cover is substantially held down. In other words, the touch of the air bag cover has been bad.
Needless to say, the bad touch above has occurred in not only such an air bag cover for operating the horn switch but also an air bag cover with a horn button provided separately.
SUMMARY OF THE INVENTION
An object of the invention intended to solve the foregoing problems is to provide an air bag in an air bag system that can be housed in a compact casing.
Another object of the present invention intended to solve the foregoing problems is to provide an air bag system capable of improving the touch of its air bag cover.
An air bag in an air bag system according to the invention wherein a peripheral wall portion on a side opposite to an opening for introducing an inflation gas is put on the side of a peripheral wall portion having the opening in such a manner as to set flatly developed peripheral edges closer to the opening side before being folded twice whereby to house the air bag in a casing, is characterized in that
the peripheral wall portion on the side opposite to the opening is put on the side of the peripheral wall portion having the opening and flatly developed; the peripheral edges in three directions around the opening are folded together closer to the opening side at the first stage; and the peripheral edges on the end portion side thus folded in the three directions around the opening are folded at the second stage in such a manner as to set the peripheral edges closer to the opening side whereby to house the air bag in the casing.
The folding at the second stage is preferably carried out under an outer roll folding method for winding each of the peripheral edges on the end portion side thus folded at the first stage on the side of the peripheral wall portion having the opening.
In this case, preferably, the casing is disposed in a boss portion in the center of a steering wheel; and the boss portion includes a space on its front portion side with respect to a ring portion to be held when the steering wheel is turned.
Further, the folding at the first stage is preferably carried out under a bellows folding method for folding the peripheral edges in the three directions around the opening on the side of the peripheral wall portion on the side opposite to the opening.
Preferably, further, the casing is disposed in the boss portion in the center of a three-spoke type steering wheel; and only one folded region out of those folded at the second stage is housed in the casing so that the region may be disposed on the front side of the steering wheel.
Further, the casing may be disposed in the boss portion in the center of a steering wheel with an inflator for generating the inflation gas disposed in the base wall portion; and only one folded region out of those folded at the second stage is disposed on the rear side of the inflator, whereas the remaining two folded region out of those folded at the second stage is disposed respectively on the lateral side of the inflator.
Further, the casing preferably has an inflator disposed in the base wall portion; and at least one folded region out of those folded at the second stage is housed in the casing with part of the one folded region being mounted on the inflator.
The air bag according to the invention is such that the peripheral edges in three directions around the opening are folded together closer to the opening side at the first stage where the flatly developed air bag is folded. Then the peripheral edges on the end portion side folded in the three directions around the opening are folded closer to the opening, so that the flatly developed air bag is ultimately folded into three packs by putting the peripheral wall portion opposite to the opening on the side of the peripheral wall portion having the opening for introducing the inflation gas.
In other words, since the air bag according to the invention consists of three folded packs, any one of the packs can be reduced in thickness and shape as viewed from top as compared with the conventional casing where two packs are formed.
Moreover, the three packs that are ultimately folded can easily be disposed radially around the opening. Since each one of the packs thus folded up is smaller in shape than the conventional pack, the air bag in top view after it has been completely folded up can be made smaller.
Therefore, the air bag in the air bag system according to the invention can readily be housed in a compact
Asano Masakazu
Ishii Tsutomu
Kikuta Mitsuhiro
Uemura Takashi
Yamamoto Tadashi
Ilan Ruth
Mai Lanna
Pillsbury & Winthrop LLP
Toyoda Gosei Co,., Ltd.
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