Land vehicles – Wheeled – Attachment
Reexamination Certificate
1999-12-14
2001-05-22
Johnson, Brian L. (Department: 3618)
Land vehicles
Wheeled
Attachment
C280S740000
Reexamination Certificate
active
06234523
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an inflator for a safety system of an automotive vehicle, and particularly, to an improvement in a dual type inflator device where a hybrid-type inflator and a pyro-type inflator are combined.
2. Background of the Prior Art
Inflators of various designs and configurations have been invented for an air bag module equipped in a vehicle. When an inflator is activated, gas component is generated for inflating an air bag. Inflators can generally be classified into different groups or types. A hybrid-type inflator includes pressurized gas stored, which acts with a gas generated by inflammable propellant to generate gas component for filling the air bag. On the other hand, in a pyro-type inflator, the entire gas that fills an air bag a propellant gas generated a solid gas generating propellant composition.
Among conventional inflator systems, a system where at least two inflators are assembled has been known. That is, inflator systems of a plurality of inflators including a dual type have been developed in various manner.
For deployment system in a dual type inflator device, various structures have been proposed in consideration of factors such as ages and/or sizes of vehicle occupants and/or positions of the vehicle occupants in a vehicle. In a known system, a plurality of gas generating units for inflating an air bag can selectively be activated. Such at least two units are activated when a relatively increased pressure should be provided in the air bag.
In systems of another prior art, such as U.S. Pat. Nos. 3,868,124, 3,972,545, 5,219,178, 5,351,988, and U.S. Pat. No. 5,564,743, a dual type inflator device has been proposed where a hybrid-type inflator is connected at its gas outlet with a pyro-type inflator having a size smaller than the hybrid-type inflator.
However, in the conventionally proposed dual type inflator device, when respective inflators have different activation timings, that is, when activation of one of the inflators is delayed from that of the other, light-emitting phenomenon, appearing like a lantern, sometimes occurs in the air bag, which is required to be eliminated.
BRIEF SUMMARY OF THE PRESENT INVENTION
According to the present invention, there is provided a dual type inflator device for inflating an air bag in a vehicle where light-emitting phenomenon is suppressed at an activation. The device of the present invention is a dual type inflator device comprising a first inflator and a second inflator. In a preferred embodiment, the first inflator is a hybrid-type inflator including first gas generating material and pressurized medium. It is preferable that such gas generating material includes fuel-rich component and is intended to warm and inflate the pressurized medium, and the pressurized medium includes a large amount of oxygen in a range of about 2 to 30% after actuating the first inflator. The pressurized medium of the first inflator preferably includes a sufficient amount of oxygen even if the first gas generating material and second gas generating material described below are combusted. The term “fuel-rich” means that the component includes oxygen in its molecular structure even in an amount smaller than chemical equivalent amount of oxygen which will be required to convert the whole hydrogen which can exist in the component to water and convert the whole carbon which can exist in the component to carbon dioxide even while the component is put in a self-support combustion reaction. When the fuel-rich component is combusted alone, gaseous product including a large amount of carbon monoxide and/or hydrogen will be generated. The carbon monoxide and hydrogen are not desirable for deploying an inflatable air bag in vehicle safety system. Particularly, gun-type propellants are preferable to be used as the fuel-rich component or fuel-rich material, the gun-type propellants are easily available and inexpensive, and their combustion characteristics are well understood. The gun-type propellant used here is a single-, double- or triple-base propellant, includes high-temperature fuel-rich component with a high combustion temperature such as nitramin propellant, for example, LOVA (low vulnerability ammunition) and HELOVA (high energy and low vulnerability ammunition). The first and second gas generating materials having the same composition, shape and the like can be used, but different kinds of propellants can also be used as the respective gas generating materials.
More specifically, the gun-type propellant is fuel-rich and has a combustion temperature of a range from about 2,500° K. to about 3,800° K. An example of a suitable gun-type propellant includes nitramine-base propellant having RDX (cyclotrimethylenetrinitramine) or HMX (cyclotetramethylene-tetranittramine) as main component. PETN (pentaerythitrol tetraanitrate) and TAGN (triaminoguanidinium nitrate) are useful as the main component in the gun-type propellant. Other suitable propellants involve ones containing tetrazole-base compound and triazole-base compound. The most preferable fuel-rich component is RDX among the gun-type propellants.
The second inflator preferably includes pyro-type inflator having fuel-rich second pyro-type gas generating material. The pyro-type inflator does not include any pressurized medium reacting with the gas components generated by the second gas generating material when the air bag is filled with the gas components. The second inflator serves mainly to warm and expand the pressurized material in the first inflator by the heat generated when the second gas generating material is combusted. According to the present invention, in the first and second inflators constituting the dual type inflator device, a diffuser assembly portion of a hybrid-type inflator constituting the first inflator is connected with an gas outlet of a pyro-type inflator constituting the second inflator, and the structure of the connecting portion is improved so that the light-emitting phenomenon that tends to occur at an activation when the second inflator is activated at a predetermined interval (for example, 20 milliseconds to 40 milliseconds or so) after the first inflator is prevented.
Namely, the present invention relates to a dual type inflator device for inflating an air bag in a vehicle, comprising a first inflator and a second inflator; the first inflator comprising a hybrid-type inflator having hybrid-type gas generating material and an activating assembly used for activating the hybrid-type gas generating material; the second inflator comprising a pyro-type inflator having pyro-type gas generating material and an activating assembly used for activating the pyro-type gas generating material; the first inflator having an inflator housing with one end at which a diffuser assembly is disposed, the inflator housing having an outlet passage communicating with the diffuser assembly, a gas flow from the inflator housing being discharged into an air bag from an outlet hole of the diffuser assembly through the outlet passage; and
an end portion of the second inflator having a gas outlet being connected to an end portion of the diffuser assembly of the first inflator, the gas outlet of the second inflator being formed in a tube configuration having a gas passage to extend into the outlet passage of the first inflator through a central portion of the diffuser assembly of the first inflator, a gas flow from the second inflator being mixed with the gas flow of the first inflator in the outlet passage. The pyro-type gas generating material contained in the second inflator serves such that the combustion component produced by combustion of the material flows into the first inflator to warm and inflate the pressurized medium in the first inflator mainly.
It is preferable that a plurality of layers of metallic net are disposed inside of the diffuser assembly of the first inflator, and after the gas flow passing through the outlet passage passes through the plurality of layers of metallic net, it is exhausted from the outle
Katsuda Nobuyuki
Tokoro Takuji
Daicel Chemical Industries Ltd.
Fischmann Bryan
Johnson Brian L.
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