Land vehicles – Wheeled – Attachment
Reexamination Certificate
2000-06-08
2002-07-30
English, Peter C. (Department: 3619)
Land vehicles
Wheeled
Attachment
C280S735000, C280S737000, C280S741000, C280S743100, C102S531000
Reexamination Certificate
active
06425601
ABSTRACT:
FIELD OF THE INVENTION
The present invention is directed to an air bag passive restraint module for motor vehicles. In particular, the invention is directed to a self-contained air bag passive restraint module, which, in a single unit, contains an air bag, inflator, power supply, and impact sensor that may be retrofitted to existing vehicles.
BACKGROUND OF THE INVENTION
In addition to seat belts, government regulations require all new automobiles sold in the United States to be equipped with an air bag as a supplemental passive restraint for each of the front seat occupants. As a result, all new cars sold in the U.S. are equipped with dual front air bags that are designed to supplement the seat belts, and to reduce injuries in a frontal collision. Typically, a small air bag is located in the steering wheel to protect the driver, and a larger air bag is stored in the dash to protect the front seat passenger. In the event of a frontal collision, the air bags are deployed in a matter of milliseconds, preventing the driver and front seat passenger from impacting on the steering wheel and dash, respectively.
However, the air bags presently installed in most motor vehicles provide little or no protection for the lower body and limbs in frontal crashes, and fail to protect vehicle occupants when the vehicle is struck from the side. Side protection is particularly important because of the increased number of light trucks, such as pickups and sports utility vehicles (“SUV's”), on the road. These light trucks are considerably heavier than typical passenger cars, and have bumpers that are higher than those of automobiles; and can cause severe damage and injuries when a passenger car is struck from the side.
To prevent injuries in side impacts, a few automobile manufacturers have begun to offer side air bags that provide head protection for front passengers in side collisions. However, side air bags are not available in most automobiles, and no manufacturer offers a vehicle equipped with front air bags for rear seat passengers. Moreover, prior art air bags are difficult, if not impossible, to install in any position, including, e.g., in the steering wheel, dash, or side of the vehicle, in existing vehicles that lack factory installed air bags. This is due, at least in part, to a lack of an acceptable inflator, and the need to wire the impact detector of such an air bag into the electrical system of the vehicle.
In addition to being difficult, if not impossible to retrofit prior art air bags in existing vehicles, prior art air bag inflators are relatively inefficient thermodynamically, and, thus, require an excessive amount of pyrotechnic material, resulting in a relatively large inflator size with resultant difficulties in packaging the inflator into tight structural spaces. The relatively slow inflation rate of certain prior art inflators is also a major disadvantage. The relatively slow inflation rate is acceptable for the deployment of a dash or steering wheel mounted air bag, which are positioned relatively close to the vehicle occupants they are designed to protect. However, air bags located in a vehicle in positions other than the steering wheel or dashboard may have less than one fourth the time available for, e.g., a dash mounted air bag to deploy to provide protection in an impact, as the vehicle occupant is far closer to the interior surface of the vehicle. This reduced distance substantially reduces the time available for deployment of an inflatable restraint, such as the side bags discussed above and knee bolsters that prevent an occupants knees from impacting on the lower part of the dashboard, and prevent the occupant from “submarining” under the seat belts.
Therefore, a need exists for an air bag module, capable of rapid inflation, that can be installed in new vehicles and in existing vehicles to provide a protective air bag at locations where such an air bag was not previously available. The present invention provides such a self-contained air bag module.
SUMMARY OF THE INVENTION
The present invention is directed to a self-contained air bag module that comprises an air bag having an interior volume in fluid communication with a high thermal efficiency inflator, where the high thermal efficiency inflator is adapted for producing a sufficient quantity of a gaseous product to substantially inflate the air bag, and an impact detector in electrical or mechanical communication with the initiator of the high thermal efficiency inflator. The preferred high thermal efficiency inflator comprises a housing having an inner surface, defining an interior volume. The housing contains a pressurized gas at a first pressure in the interior volume and a pyrotechnic material for producing heat upon combustion, where the pyrotechnic material has a burn rate that is accelerated at the first pressure in comparison to the burn rate at a pressure of one atmosphere. The pyrotechnic material is stored within the interior volume of the housing at a distance from the inner surface of the housing, such that the stored pyrotechnic material is subjected to the first pressure of the pyrotechnic material, and the pyrotechnic material, in and of itself, is substantially free of thermal contact with the housing before combustion of the pyrotechnic material.
The preferred high thermal efficiency inflator further comprises an ignitor for initiating combustion of the pyrotechnic material upon receipt of an initiation signal; and means for maintaining the pressurized gas at the first pressure within the interior volume, and to open when the gas attains a predetermined second, higher pressure upon heating of the pressurized gas by combustion of the pyrotechnic material to allow an inflation gas to pass from the housing. In the preferred inflator, the pyrotechnic material is present in an amount sufficient to produce at least about 20 mole percent of the inflation gas, and the pressurized gas is present in an amount sufficient to produce up to about 80 mole percent of the inflation gas.
The first pressure of the gas in the preferred high thermal efficiency inflator is sufficiently high to produce an aerodynamic drag on burning pyrotechnic material passing through the gas, thereby slowing the burning pyrotechnic material, such that the drag produced on the burning pyrotechnic material and the distance between the stored pyrotechnic material and the inner surface of the housing are sufficiently great that, upon combustion of the pyrotechnic material, contact between a sufficient amount of the burning pyrotechnic material and the inner surface of the housing is prevented to allow at least about 90 percent of the heat produced by the combustion of the pyrotechnic material to be transferred to the inflation gas, so that no more than about 10 percent of the heat is transferred to the housing, resulting in a thermal efficiency of the high thermal efficiency inflator of at least about 90 percent.
In the most preferred self-contained air bag module of the invention, the pyrotechnic material in the inflator is located within the inflator housing in a frangible container that ruptures upon combustion of the pyrotechnic material, or in a container formed from a combustible material that burns upon combustion of the pyrotechnic material, releasing heat. Preferably, the combustible material is deep draw steel, aluminum or a combination of palladium and aluminum.
In an alternative embodiment, the pyrotechnic material is located within the housing in a container comprising a plug formed from a frangible or combustible material, such that, upon combustion of the pyrotechnic material, the plug ruptures or burns, allowing particles of burning pyrotechnic material to pass through the gas, transferring heat to the gas. The container may also define a plurality of apertures or pores, where the apertures or pores are of a sufficient size and a sufficient number to allow combusting particles to pass into the interior volume from the porous container through the pores, thereby heating the pressurized gas. In addition, the pyrotechni
English Peter C.
Holden Jerry J.
Titus John D.
Universal Propulsion Company, Inc.
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