Land vehicles – Wheeled – Attachment
Reexamination Certificate
1997-11-21
2001-02-20
Dickson, Paul N. (Department: 3618)
Land vehicles
Wheeled
Attachment
C280S741000
Reexamination Certificate
active
06189924
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates generally to inflators for use in inflating inflatable restraint airbag cushions, such as used to provide impact protection to occupants of motor vehicles. More particularly, the invention relates to plural stage inflators such as may provide an inflation gas output which is adaptive to factors such as one or more crash and occupant conditions.
It is well known to protect a vehicle occupant using a cushion or bag, e.g., an “airbag,” that is inflated or expanded with gas when the vehicle encounters sudden deceleration, such as in a collision. In such systems, the airbag cushion is normally housed in an uninflated and folded condition to minimize space requirements. Upon actuation of the system, the cushion begins being inflated in a matter of no more than a few milliseconds with gas produced or supplied by a device commonly referred to as “an inflator.”
Various types of inflator devices have been disclosed in the art for the inflation of an airbag such as used in inflatable restraint systems. One type of known inflator device derives inflation gas from a combustible pyrotechnic gas generating material which, upon ignition, generates a quantity of gas sufficient to inflate the airbag.
A second type of known inflator device forms airbag inflation gas from a combination of stored compressed gas and the combustion of a solid form of a pyrotechnic gas generating material. This type of inflator device is commonly referred to as a hybrid inflator.
A new type an inflator, called a “fluid fueled inflator,” has been developed. Such inflators are the subject of commonly assigned Smith et al., U.S. Pat. No. 5,470,104, issued Nov. 28, 1995; Rink, U.S. Pat. No. 5,494,312, issued Feb. 27, 1996; and Rink et al., U.S. Pat. No. 5,531,473, issued Jul. 2, 1996, the disclosures of which are fully incorporated herein by reference.
Such inflator devices utilize a fuel material in the form of a fluid, e.g., in the form of a gas, liquid, finely divided solid, or one or more combinations thereof, in the formation of an inflation gas for an airbag. In one such inflator device, the fluid fuel material is burned to produce gas which contacts a quantity of stored pressurized gas to produce inflation gas for use in inflating a respective inflatable device.
In view of possibly varying operating conditions and, in turn, possibly varying desired performance characteristics, there is a need and a desire to provide what has been termed an “adaptive” inflator device and corresponding inflatable restraint system. With an adaptive inflator device, output parameters such as the quantity, supply, and rate of supply of inflation gas, for example, can be selectively and appropriately varied dependent on selected operating conditions such as ambient temperature, occupant presence, seat belt usage and rate of deceleration of the motor vehicle, for example.
While such adaptive systems are desirable, they typically require the inclusion of additional components as a part of the associated inflator device, thus increasing the size of the inflator. As such it has been even more difficult to provide an adaptive inflator which will meet the size requirements for vehicles, especially for driver side applications.
Thus, there remains a need for an adaptive inflator device of simple design and construction will meet the size requirements for vehicles, especially for driver side applications.
SUMMARY OF THE INVENTION
A general object of the invention is to provide an improved inflator, inflatable restraint system and associated or corresponding methods of operation.
A more specific objective of the invention is to overcome one or more of the problems described above.
The general object of the invention can be attained, at least in part, through a plural stage inflator for use in inflating an inflatable restraint airbag cushion. The inflator includes a housing which defines a first chamber which contains a first gas generant material and a second chamber which contains a second gas generant material. The inflator also includes an igniter device which includes a dual output squib with first and second igniter chambers containing respective first and second igniter charges. Upon activation, the dual output squib selectively ignites at least one of the first and second igniter charges, with the dual output squib having:
a) a first stage discharge whereby the first igniter charge is ignited to produce combustion products which in turn pass to the first chamber to ignite the first gas generant material to produce inflation gas at a first output level and
b) a second stage discharge whereby the second igniter charge is ignited to produce combustion products which in turn pass to the second chamber to ignite the second gas generant material to produce inflation gas at a second output level.
The prior art fails to provide a plural stage inflator design as simple as desired. More particularly, the prior art fails to provide a plural stage inflator and associated inflatable restraint system, particularly an inflator for a driver side inflatable restraint system installation, wherein the inflator incorporates a single component, dual output squib and the system includes an inflator external inflation media filter material, particularly to the exclusion of an inflator internal filter.
In accordance with an alternative embodiment, the invention comprehends a plural stage inflator which includes a housing having a top wall, a bottom wall, and a generally cylindrical sidewall defining an upper annular chamber containing a first gas generant and an adjacent lower annular chamber containing a second gas generant. The sidewall of the inflator housing defines a plurality of gas exhaust openings from the upper and lower annular chambers. The inflator also includes igniter device which includes a dual output squib, an upper igniter chamber containing a first igniter charge, and a lower igniter chamber containing a second igniter charge. Upon activation, the dual output squib, selectively ignites at least one of the first and second igniter charges, with the dual output squib having:
a) a first discharge output whereby the first igniter charge is ignited to produce combustion products which in turn pass to the first chamber to ignite the first gas generant material to produce inflation gas at a first output level and
b) a second discharge output whereby the second igniter charge is ignited to produce combustion products which in turn pass to the second chamber to ignite the second gas generant material to produce inflation gas at a second output level.
The invention still further comprehends an inflatable restraint system which includes specified inflator assembly, filter, inflatable airbag cushion and cushion retainer constructions. Specifically, the inflator assembly includes a generally circular cylindrical housing. The housing has a top wall, a bottom wall, a generally cylindrical sidewall defining a plurality of gas exhaust openings, and a peripheral bracket extending radially outwardly from the cylindrical sidewall below the plurality of gas exhaust openings. The housing defines a first chamber containing a first gas generant material and a second chamber containing a second gas generant material.
The inflator assembly also includes a single component igniter device which includes a dual output squib and has first and second igniter chambers containing respective first and second igniter charges. Upon activation, the dual output squib selectively ignites at least one of the first and second igniter charges, with the dual output squib having:
a) a first stage discharge whereby the first igniter charge is ignited to produce combustion products which in turn pass to the first chamber to ignite the first gas generant material to produce inflation gas at a first output level and
b) a second stage discharge whereby the second igniter charge is ignited to produce combustion products which in turn pass to the second chamber to ignite the second gas generant material to produce inflation gas at a second ou
Autoliv ASP Inc.
Brown Sally J.
Dickson Paul N.
Fleming Faye M.
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