Airbag device

Land vehicles – Wheeled – Attachment

Reexamination Certificate

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Details

C280S741000

Reexamination Certificate

active

06454299

ABSTRACT:

BACKGROUND OF THE INVENTION
The present invention relates to an airbag device having an inflator which generates gas for inflating and deploying an airbag. More particularly, the invention relates to a device having an inflator of a type that a combustion chamber and a filter chamber are separately provided.
Regardless of the type of airbags (e.g. driver airbags, front-passenger airbags, side impact airbags, and curtain airbags), conventional pyrotechnic inflators generally fall into the following two types: a type wherein the propellant and a filter are housed in one chamber (for example, a one-chamber type as disclosed in WO9908907); and a type where these components are housed in respective separate chambers (for example, a two-chamber type as disclosed in DE29819168U1). That is, the one-chamber type inflator has one chamber in which propellant and a filter are housed. The two-chamber type inflator comprises a combustion chamber in which propellant is filled, a filter chamber in which a filter is housed, and a partition provided between the combustion chamber and the filter chamber wherein the partition is formed with a hole for allowing the communication between the combustion chamber and the filter chamber from the initiation of combustion until the combustion pressure reaches the maximum value. The combustion gas starts to flow into the filter chamber at the initiation of combustion. This inflow of gas causes a little delay to rise the combustion pressure to the maximum value. Further, the delay slows the speed of combustion.
It is desired to shorten the starting timing of rising the inner pressure of an airbag and to shorten the time period required from the start of rising of the inner pressure until the inner pressure reaches the maximum value, for improving the initial restraining capability of an airbag device.
It is desired to provide an inflator which has an increased degree of freedom of design for positioning a gas port.
It is desired to provide an inflator which provides for an increased degree of freedom of design for easily changing its profile to be suitable for any housing space.
SUMMARY OF THE INVENTION
In order to solve the above-described problems, an inflator of the present invention comprises: a propellant, an igniter for igniting the propellant, a combustion chamber in which the propellant is burned, a filter chamber in which a filter is accommodated, a partition separating the combustion chamber and the filter chamber, communication orifices formed in the partition for allowing the communication between the combustion chamber and the filter chamber, and gas ports for supplying inflating gas into an airbag, and further comprising a closing mechanism which provides for an air tight closure at the communication orifices until the inner pressure of the combustion chamber reaches a predetermined pressure.
According to this structure, the combustion chamber is closed so that the pressure in the combustion chamber rises quickly. The closing mechanism releases when the pressure reaches the predetermined pressure, thereby reducing the delay in the start of rising the inner pressure of an airbag, shortening the time period required from the start of rising of the inner pressure until the inner pressure reaches the maximum value, and thus improving the initial restraining capability of an airbag device.
The inflator of the present invention is characterized in that the closing mechanism breakable members which can be broken at the predetermined pressure. According to this structure, inexpensive breakable members such as aluminum film can be employed as the closing mechanism or means.
The inflator of the present invention is further characterized in that the predetermined pressure is slightly lower than the maximum combustion pressure of the propellant in the combustion chamber. According to this structure, the reliability of releasing action of the closing mechanism can be improved because the action is not affected by variation in the maximum combustion pressure due to individual differences of the propellant.
The inflator of the present invention is characterized in that the predetermined pressure is a value around the lower limit of a variation range of the maximum combustion pressure. According to this structure, the reliability of releasing action of the closing mechanism can be improved because the action is not affected by variation in the maximum combustion pressure due to individual differences of the propellant.
An airbag device according to the present invention may include: a propellant, an igniter for igniting the propellant, a combustion chamber in which the propellant is burned, a filter chamber in which a filter is accommodated, a partition separating the combustion chamber and the filter chamber, communication orifices formed in the partition for allowing communication between the combustion chamber and the filter chamber, and gas ports for supplying inflating gas into an airbag, and is characterized in that the gas ports can be formed at any places in the outer periphery of the inflator, except a portion adjacent to the combustion chamber.
According to this structure, the gas ports may be formed in almost all outer periphery adjacent to the filter chamber, thus increasing the degree of freedom of design for positioning gas ports. In addition, the filter can be used as heat-absorbing mechanism through its entire surface, thus improving the endothermic effect of the filter.
An airbag device of the present invention is characterized by comprising an airbag connected to the aforementioned inflator. According to this structure, an airbag device can be obtained which has excellent rising characteristics of the inner pressure of the airbag.
The airbag device of the present invention is characterized in that the airbag has a gas inlet facing to the gas ports of the aforementioned inflator. According to this structure, the gas inlet of the airbag is disposed to face to the gas ports so as to cope with multidirectional or bidirectional gas spouted out simultaneously from the gas ports of the inflator of this type, thereby effectively introducing the inflating gas of the inflator of this type into the airbag. This structure can speed up the initial deployment of the airbag or can deploy multiple areas of airbags at once.
In an alternative embodiment, an inflator of the present invention may comprise: a propellant, an igniter for igniting the propellant, a combustion chamber in which the propellant is burned, a filter chamber in which a filter is positioned, a partition separating the combustion chamber and the filter chamber, communication orifices formed in the partition for allowing the communication between the combustion chamber and the filter chamber, and gas ports for supplying inflating gas into an airbag, and wherein the combustion chamber and the filter chamber are arranged in parallel in the longitudinal direction with the partition being interposed therebetween.
According to this structure, the inflator can be made to be short in the longitudinal direction and thin in the thickness so that the inflator can be suitably used in such a case to be housed in a limited space such as an A-pillar, a B-pillar, a C-pillar, and a space behind a garnish. By arranging the combustion chamber and the filter chamber to be offset in parallel or making the filter chamber longer than the combustion chamber in the longitudinal direction, the projecting portion of the filter chamber can be effectively used as a connecting portion with the airbag. Ends of the projecting portion can be provided with gas ports.
An airbag device of the present invention is characterized by comprising an airbag which can be connected to the connecting portion of the aforementioned inflator. According to this structure, a curtain airbag device or a side impact airbag device can be obtained which has excellent rising characteristics of the inner pressure of the airbag.
In another alternative embodiment, the inflator of the present invention is characterized in that the filter chamber ha

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