Adaptive inflation performance using magnetic characteristics of gases

An inflation system and method of operation are provided which utilize or employ the magnetic characteristics of certain gases to selectively alter or change one or more inflation characteristic of the inflation output provided thereby or resulting therefrom. An inflation system for providing a supply of inflation medium to an inflatable restraint element includes an inflator device having a first chamber having contents including a quantity of at least one gaseous material having magnetic characteristics. The inflation system also includes a magnetic field inductor in magnetic field change inducing communication with at least a portion of the first chamber contents quantity of the at least one gaseous material having magnetic characteristics, wherein activation of the magnetic field inductor effects a change in at least one inflation characteristic of the inflator device, e.g., rise rate, gas mass flow rate and pressure output, produced or generated by the inflator.

BACKGROUND OF THE INVENTION

This invention relates generally to gas generation, production or supply such as used for or in association with the inflation of inflatable devices such as inflatable vehicle occupant restraint airbag cushions used in vehicular inflatable restraint systems. More particularly, the invention relates to inflation systems such as for use in providing a supply of inflation medium to an inflatable restraint element and related methods of operation which employ or utilize magnetic characteristics of gases.

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 a sudden deceleration, such as in the event of a collision. In such systems, an airbag cushion is normally housed in an uninflated and folded condition to minimize space requirements. Upon actuation of the system, the cushion begins to be 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.”

Many types of inflator devices have been disclosed in the art for use in inflating one or more inflatable restraint system airbag cushions. Many prior art inflator devices include a solid form of gas generant material which reacts to produce or form gas used in the inflation of an associated airbag cushion.

A common form or type of prior art inflator device includes a gas generant material in a solid form and which solid gas generant material is caused to react to produce or form gas used in the inflation of an associated airbag cushion. For example, such inflators can generally produce or derive inflation gas via the combustion of a solid form gas generating material, i.e., a pyrotechnic. In practice, the combustion of such gas generating materials can typically also produce various undesirable combustion products, including various solid particulate materials. The removal of such solid particulate materials, such as by the incorporation of various filtering devices within or about the inflator, can undesirably increase inflator design and processing complexity as well as the costs associated with such inflator devices and associated processing. In addition, the temperature of the gases emitted from such inflator devices can typically vary between about 500° F. (260° C.) and about 1200° F. (649° C.), dependent upon numerous interrelated factors including the desired level of inflator performance, as well as the type and amount of gas generant material. Consequently, airbag cushions used in conjunction with such inflator devices are commonly constructed of or coated with special materials such as to desirably be resistant to such high temperatures. As will be appreciated, such specially fabricated or prepared airbag cushions are typically more costly to manufacture and produce.

Another category of inflator devices disclosed in the art for the inflation of one or more inflatable restraint system airbag cushions is often referred to as “compressed gas inflators.” This category of inflator devices generally refers to those inflator devices which contain a selected quantity of compressed gas. For example, one particular type of compressed gas inflator, commonly referred to as a “stored gas inflator,” simply contains a quantity of a stored compressed gas which is selectively released to inflate an associated airbag cushion. A second type of compressed gas inflator, commonly referred to as a “hybrid inflator,” typically supplies or provides inflation gas as a result of combining a stored compressed gas with the combustion products resulting from the combustion of a gas generating material, e.g., a pyrotechnic.

In the past, compressed gas inflators of various types have commonly been at a disadvantage, as compared to pyrotechnic inflators, in terms of size, weight and/or cost. This is especially significant in view of the general design direction toward relatively small, lightweight and economical modem vehicle components and assemblies. Thus, there is a continuing need and demand for further improved apparatus and techniques for inflating inflatable devices such as inflatable airbag cushions.

A more recently developed type of inflator device is at least in part the subject of commonly assigned Rink, U.S. Pat. No. 5,669,629, issued 23 Sep. 1997; Rink et al., U.S. Pat. No. 5,884,938, issued 23 Mar. 1999; and Rink et al., U.S. Pat. No. 5,941,562, issued 24 Aug. 1999, the disclosures of which patents are hereby and expressly incorporated herein in their entirety. In one form of such recently developed inflator device, inflation gas is produced or formed, at least in part, via the decomposition or dissociation of a selected gas source material, such as in the form of a compressed gas and such as via the input of heat from an associated heat source supply or device. Such an inflator device is sometimes referred to as a “dissociative inflator.”

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 generally termed or referred to as an “adaptive” inflator device and a corresponding inflatable restraint system. With an adaptive inflator device, output parameters such as one or more of the quantity, supply, and rate of supply (e.g., mass flow rate) of inflation gas, for example, can be selectively and appropriately varied dependent on one or more selected operating condition such as ambient temperature, occupant presence, seat belt usage and rate of deceleration of the motor vehicle, for example.

Perhaps one of the simplest forms of a prior art adaptive inflation system is an inflation system which utilizes an inflator which provides two levels or stages of performance, e.g., commonly called or referred to as a “two-stage” or “dual stage” inflator. Various proposed or currently available dual stage inflator devices appear to be based on the principal of packaging together two separate inflators. As a result, such inflator combinations commonly include two distinct pressure vessels, two sets of filter or inflation gas treatment components, e.g., one for the output of each of the pressure vessels, and two distinct diffusers, again one for the output of each of the pressure vessels. Thus, it has been difficult to provide an adaptive inflator which will satisfactorily meet the size, cost and weight limitations associated with modern vehicle design, particularly as it pertains to driver side applications. Moreover, those skilled in the art will appreciate that even such a relatively simple two-stage inflator may require significantly sophisticated actuation and/or control systems, as compared to typical single stage inflators, in order to realize particularly desired adaptive performance capabilities.

Commonly assigned Rink et al., U.S. Pat. No. 5,941,562, issued 24 Aug. 1999 discloses an improved adaptive output inflator wherein inflator performance, such as measured by inflator gas output, can be appropriately varied and selected by appropriately varying and selecting the operational oxidant composition of the inflator.

While the devices and methods disclosed therein have in general at least in part been successful in satisfying the need and demand for improved adaptive output inflators and methods of inflation, there remains a continuing need and demand for further improved inflation systems and methods of operation such as may improve one or more of the safety, simplicity, effectiveness, economy, and reliability thereof, particularly as applied to adaptive inflation systems and operation.

SUMMARY OF THE INVENTION

A general object of the invention is to provide an improved inflation system for providing a supply of inflation medium to an inflatable restraint element and method 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 an inflation system for providing a supply of inflation medium to an inflatable restraint element. The inflation system includes an inflator device having a first chamber. The first chamber has contents including a quantity of at least one gaseous material having magnetic characteristics. The inflation system also includes a magnetic field inductor in magnetic field change inducing communication with at least a portion of the first chamber contents quantity of the at least one gaseous material having magnetic characteristics. In accordance with one preferred practice of the invention, activation of the magnetic field inductor effects a change in at least one inflation characteristic of the inflator device.

The prior art generally fails to provide an inflation system and method of operation wherein one or more of safety, simplicity, effectiveness, flexibility, economy and reliability is as great as may be desired. The prior art, more particularly, generally fails to provide an inflation system and method of operation wherein the magnetic characteristics of an inflation medium gas are employed to selectively vary the inflation characteristics of an inflator device.

The invention further comprehends a method for operating an inflator device. In accordance with one preferred embodiment of the invention, such a method involves placing a quantity of at least one gaseous material having magnetic characteristics in a first chamber of the inflator device and, subsequently, inducing a change in the magnetic characteristics of at least a portion of the quantity of the at least one gaseous material to effect a change in at least one inflation characteristic of the inflator device.

As used herein, references to an “adaptive” inflation system and the like are to be understood to refer to inflatable device inflation wherein selected inflatable devices are inflated or inflated in a manner generally dependent on selected operating conditions such as one or more of ambient temperature, occupant presence, seat belt usage, seat position of the occupant and rate of deceleration of the motor vehicle, for example.

References herein to the detection or sensing of “occupant presence” are to be understood to refer to and include detection and sensing of one or more of the size, weight, and/or positions of a particular occupant under consideration.

References herein to inflator or inflation gas “output” are to be understood to refer to inflator performance output parameters such as the quantity, supply, and rate of supply of inflation gas. With “adaptive output inflators,” the inflator output is generally dependent on selected operating conditions such as ambient temperature, occupant presence, seat belt usage and rate of deceleration of the motor vehicle, for example.

References herein to an “inflation characteristic” of an inflator or like device generally refer to one or more of the rise rate, gas mass flow rate and pressure output, e.g., maximum pressure (PMAX), produced or generated by the inflator.

References herein to the “rise rate” produced by or resulting from an inflator device generally refer to the rate at which the output from the inflator device increases in pressure, as measured when such gas output is directed into a closed volume.

Reference herein to “PMAX” generally refers to the maximum pressure that an inflator device generates or produces, as measured when the inflation output from the device gas is directed into a closed volume.

References herein to a “pyrotechnic” material are to be understood to generally refer to a material which in its simplest form, consists of an oxidizing agent and a fuel that produce an exothermic, self-sustaining reaction when heated to the ignition temperature thereof.

References herein to a specific composition, component or material as a “fuel” are to be understood to refer to a chemical which generally lacks sufficient oxygen to burn completely to CO2, H2O and N2.

Correspondingly, references herein to a specific composition, component or material as an “oxidizer” are to be understood to refer to a chemical generally having more than sufficient oxygen to burn completely to CO2, H2O and N2.

References herein to a material or pyrotechnic composition or the like as being “fuel-rich” or “rich in fuel” generally refers to such material as contains or includes fuel in a relative amount, as compared to the amount of oxidizer therein contained, in excess of the theoretical stoichiometric amount which will undergo complete combustion, based on the amounts of fuel and oxidizer therein contained.

DETAILED DESCRIPTION OF THE INVENTION

The present invention may be embodied in a variety of different structures. As representative,FIG. 1illustrates the present invention as embodied in an inflation system, more particularly, a gas generating device, generally designated by the reference numeral10. While such gas generating devices may find various uses, the invention is believed to have particular utility for supplying gas such as may be used in the inflation of an inflatable vehicle occupant restraint, e.g., an inflatable airbag cushion, not shown. As identified above, such gas supplying devices are commonly referred to as inflators.

As more fully described below, the invention advantageously utilizes or employs gaseous materials having magnetic characteristics in inflator devices to desirably change or alter one or more inflation characteristic of the inflator device. Further, while the invention is described hereinafter with particular reference to an inflator for an airbag assembly such as for use in various automotive vehicles including vans, pick-up trucks, and particularly automobiles, it is to be understood that the invention also has applicability not only with various types or kinds of airbag module assemblies for automotive vehicles including driver, passenger, side impact, curtain and carpet airbag assemblies, for example, but also with other types of vehicles including, for example, airplanes, as well as possibly other inflation applications.

Returning toFIG. 1, the inflator10is an assembly that comprises a pressure vessel12at least in part forming a chamber14. When the inflator10is in an at rest or static state, the chamber14is filled and pressurized with contents, here designated by the reference numeral16, and which contents are more fully described below. In view thereof, the chamber14is sometimes hereinafter referred to as a “storage chamber.”

The chamber14is generally defined at least in part by an elongated cylindrical sleeve20having a first end22and a second end24. The sleeve first end22is closed by means of an end wall26. The end wall26can be formed continuous and in one piece with the cylindrical sleeve20, as shown. Alternatively, the end wall26can be appropriately joined to or connected with the cylindrical sleeve such as by means of a weld or other suitable means, as may be desired. The inflator assembly10also includes a wall portion or segment28at least partially closing the sleeve second end24. The wall portion28includes an opening30therein. The opening30is normally closed by sealing means, e.g., such as by means of a burst or rupture disc32such as secured and joined thereto in sealing relation such as is known in the art.

An initiator and diffuser assembly combination34is joined or attached at the sleeve second end24in sealing relation such as by a weld, crimp or other suitable hermetic seal. The initiator and diffuser assembly combination34includes a base wall portion36and a side wall portion40extending therefrom. The initiator and diffuser assembly combination34also defines a diffuser chamber42and includes a plurality of diffuser orifices44, formed in the sidewall portion40, for dispensing inflation gas from the inflator10into an associated inflatable airbag cushion (not shown).

The base wall portion36includes or has an opening48therein, wherethrough an initiator device50is desirably attached in sealing relation, such as via a weld, crimp or other suitable seal. The initiator device50may, if desired, include or contain a load of a selected pyrotechnic charge which can be advantageous in providing a large heat input such as may be desired for certain associated reaction processing. The initiator device50includes a discharge end52whereat a discharge formed by the initiator device can be appropriately discharged or otherwise released.

A magnetic field inductor54, with lead wires56, is attached at, near to or adjacent the first end22of the elongated cylindrical sleeve20. The magnetic field inductor54is shown located inside the storage chamber14. However, a suitable magnetic field inductor may, if desired, be located outside the first chamber14or otherwise appropriately positioned such as to produce or result in a non-uniform magnetic field, such as described herein.

Suitable magnetic field inductors for use in the practice of the invention may include various types of devices such as can be actuated or otherwise selectively activated to produce, form or otherwise result in the formation of a magnetic field. More particularly, an example of one specific type or form of magnetic field inductor useable in the practice of the invention is an electromagnet whereby a non-uniform magnetic field can be activated such as by means of a switch.

As will be appreciated, the inside or outside placement of such a magnetic field inductor in accordance with particular preferred embodiments of the invention may have associated therewith certain advantages or benefits. For example, placement or positioning of the magnetic field inductor within the desired storage chamber may facilitate the desirable creation thereby of a strong non-uniform magnetic field within the chamber. On the other hand, placement or positioning of the magnetic field inductor outside of the desired storage chamber may desirably serve to avoid or minimize the creation of possible leak paths from the storage chamber as electrical connections (commonly referred to as “feedthroughs”) to the magnetic field inductor within the storage chamber can be avoided.

As will be appreciated by those skilled in the art and guided by the teachings herein provided, the magnetic field inductor is desirably designed and positioned such as to create or result in a non-uniform magnetic field within the associated inflator device. For example, in the embodiment shown inFIG. 1, the magnetic field inductor54is desirably positioned such that there is a strong magnetic field within or at one portion of the inflator10, here the inflator storage chamber first end22, and a negligible magnetic field is created or present within or at another portion of the inflator10, here the inflator storage chamber second end24.

In the inflator assembly10, an internal heater70is also shown disposed inside the storage chamber14. In the illustrated embodiment, the internal heater70is generally disposed at or near the second end24of the elongated cylindrical sleeve20and away from the magnetic field inductor54. In accordance with a preferred embodiment, the internal heater70may preferably contain or be composed of a pyrotechnic reactant. Those skilled in the art and guided by the teachings herein provided will however appreciate that the broader practice of the invention is not necessarily limited to the inclusion of an internal heater or the inclusion of an internal heater which contains or includes a pyrotechnic reactant as other types or forms of heater devices can, if desired, be used in the practice of the invention.

As identified above, the storage chamber14is filled and pressurized with contents16. In accordance with one preferred embodiment of the invention, the storage chamber14contains at least one gaseous material (such as oxygen) having magnetic properties. In accordance with another preferred embodiment of the invention, the storage chamber14contains a pressurized gas mixture including at least one gaseous material (such as oxygen) having magnetic properties and at least one gaseous material free or relatively free of magnetic characteristics (as compared to the gaseous material, such as oxygen, having magnetic properties in accordance with the invention). In accordance with certain preferred embodiments of the invention, the storage chamber contents16include a quantity of nitrous oxide.

Most gases are “diamagnetic”, meaning that these gases are not magnetic under normal conditions and only weakly magnetic, at best, when under the influence of powerful magnetic fields. Diamagnetic materials are popularly considered to be non-magnetic and are hereinafter sometimes referred to as being “free of magnetic characteristics”. Further, diamagnetic materials though generally carrying no permanent magnetic moment, when under the influence of a magnetic field are generally repelled or repulsed by the field. In contrast, other materials, commonly termed “ferromagnetic”, exhibit strong magnetic dipole moments under even ordinary conditions. Iron is an example of a ferromagnetic material. However, another category of materials, commonly termed “paramagnetic”, exhibit noticeable magnetic dipole moments when exposed to magnetic fields of even only moderate strength, with paramagnetic materials being attracted to the field. Paramagnetic materials include gases such as oxygen and nitric oxide. As detailed below, the invention advantageously employs one or more gaseous materials having magnetic characteristics, e.g., a paramagnetic material, particularly an oxidant gas source such as oxygen, to desirably affect one or more inflation characteristic of the inflator device.

When the magnetic field inductor54is activated or in an “on” condition or state, a non-uniform magnetic field is generated in the gas mixture within the storage chamber14. More particularly, the magnetic field inductor54, when activated, will tend to attract gaseous materials having magnetic characteristics and repulse gaseous materials free of magnetic characteristics. As a result, gaseous materials having magnetic characteristics in accordance with the invention will concentrate in, at or near the inflator storage chamber first end22and gaseous materials free of magnetic characteristics will concentrate in, at or near the inflator storage chamber second end24. When the magnetic field inductor54is inactivated or in an “off” condition or state, the contents of the storage chamber14will tend to mix together such that the gas concentration within the storage chamber14will, over time, become uniform.

As will be appreciated, magnetic field inductors used in the practice of the invention may alternatively be set or designed to be activated, e.g., “on”, or inactivated, e.g., “off”, when the inflator device is in the static state or at-rest condition, as may be desired in a particular application.

During activation of the inflator10, such as upon the sensing of the occurrence of a collision, an electrical signal is sent to the initiator device50. The initiator device50functions to rupture or otherwise open the burst disk32. When the initiator device50is a pyrotechnic-containing initiator, the initiator device50discharges combustion products toward the burst disk32. The burst disk32ruptures such that the storage chamber contents16are at least in part released from the storage chamber14and are passed into the diffuser chamber42and ultimately out the diffuser orifices44into an associated inflatable vehicle occupant restraint (not shown).

When the internal heater70contains or includes a pyrotechnic reactant, the pyrotechnic-containing initiator device50desirably produces a sufficient quantity of hot combustion particles to ignite the pyrotechnic reactant of the internal heater70.

In accordance with one preferred embodiment of the invention, the internal heater70contains or includes a fuel-rich pyrotechnic reactant and the storage chamber contents16include a quantity of at least one gaseous material having magnetic characteristics (e.g., oxygen) as well as a quantity of one or more gaseous materials free of magnetic characteristics, such as an inert gas such as argon, for example.

In such an embodiment, when the magnetic field inductor54is inactivated or otherwise in an off state or condition, the oxygen will mix with the other gas or gases (e.g., argon) and will, over time, be in relatively uniform concentration throughout the storage chamber14.

However, when the magnetic field inductor54is activated, the oxygen gas will be attracted thereto and thus towards the inflator storage chamber first end22and away from the internal heater70, disposed or positioned at or near the inflator storage chamber second end24. Consequently, the oxygen concentration in the gas mixture surrounding the internal heater pyrotechnic reactant will be low. As a result, a fuel-rich pyrotechnic reactant will be relatively slow to ignite and complete combustion of the fuel component of the internal heater pyrotechnic reactant will be delayed. Such operation will generally supply or provide an inflation medium at a relatively slow rate and hence will provide or result in a relatively slow “rise rate”.

The invention has been described above making specific reference to a preferred embodiment relying on the incorporation and/or use of one or more gaseous materials having magnetic characteristics, e.g., a paramagnetic material, particularly an oxidant gas source such as oxygen, and at least one gaseous material free of magnetic characteristics. Those skilled in the art and guided by the teachings herein provided, however, will appreciate that the invention can, if desired, be practiced by employing gases having magnetic characteristics of different degrees or magnitudes.

Thus, the invention provides an inflator device of relatively simple construction and operation and wherein an inflation characteristic such as rise rate can desirably be relatively simply and easily manipulated. In particular, selective placement and choice of pyrotechnic gas generant can be used in association with inflator assemblies such as herein described to provide inflators having specific desired inflation or performance characteristics.

Those skilled in the art and guided by the teachings herein provided will, however, appreciate that thermal effects can impact the ability of a magnetic field to separate gases with differing magnetic susceptibilities. For example, for a tube exposed to a magnetic field gradient such that the magnetic intensity is Hmaxat one end and negligible at the other end of the tube, the ratio of magnetic energy density to thermal density can be expressed as:Magnetic⁢⁢energy⁢⁢densityThermal⁢⁢energy⁢⁢density=(x1-x2)⁢μ0⁢⁢H2/2R⁢⁢M⁢⁢T/ρ(1)
Where:x1, x2=magnetic susceptibility of the gases1and2, respectivelyH=magnetic field gradientμ0=magnetic momentρ=mass densityM=molecular weight of the gas mixtureT=gas temperatureR=Universal Gas Constant

As will be appreciated, the efficiency of the process of separating gases1and2will generally correspond to the ratio of magnetic energy density to thermal energy density, with the separation process generally being more efficient when the ratio of magnetic energy density to thermal energy density is relatively large.

FIG. 2illustrates an inflator assembly210specifically designed and adapted, in accordance with one preferred embodiment of the invention, to at least in part counter the possibly deleterious or undesired effects of thermal mixing

The inflator assembly210is generally similar to the inflator assembly10shown in FIG.1and described above. For example, the inflator assembly210, similar to the inflator assembly10, comprises a pressure vessel212that at least in part forms a chamber214, with contents designated by the reference numeral216. The chamber214is generally defined at least in part by an elongated cylindrical sleeve220having a first end222and a second end224. The sleeve first end222is closed by means of an end wall226. The end wall226can be formed continuous and in one piece with the cylindrical sleeve220, as shown. The inflator assembly210also includes a wall portion or segment228at least partially closing the sleeve second end224. The wall portion228includes an opening230therein. The opening230is normally closed by sealing means, e.g., such as by means of a burst or rupture disc232such as secured and joined thereto in sealing relation such as is known in the art.

An initiator and diffuser assembly combination234is joined or attached at the sleeve second end224in sealing relation such as by a weld, crimp or other suitable hermetic seal. The initiator and diffuser assembly combination234includes a base wall portion236and a side wall portion240extending therefrom. The initiator and diffuser assembly combination234also defines a diffuser chamber242and includes a plurality of diffuser orifices244, formed in the sidewall portion240, for dispensing inflation gas from the inflator210into an associated inflatable airbag cushion (not shown).

The base wall portion236includes or has an opening248therein, wherethrough an initiator device250is desirably attached in sealing relation, such as via a weld, crimp or other suitable seal. As identified above, the initiator device250may, if desired, include or contain a load of a selected pyrotechnic charge which can be advantageous in providing a large heat input such as may be desired for certain associated reaction processing. The initiator device250includes a discharge end252whereat a discharge formed by the initiator device can be appropriately discharged or otherwise released.

The inflator assembly210also includes a magnetic field inductor254, with lead wires256, such as identified above and such as attached at, near to or adjacent the first end222of the elongated cylindrical sleeve220, as detailed below.

The inflator assembly210primarily differs from the inflator assembly10through the inclusion of a barrier, here designated by the reference numeral260. The barrier260, such as in the form of a bulkhead or the like, is positioned within the pressure vessel212and serves to essentially separate the chamber214or otherwise form or create adjacent first and second chambers262and264, respectively. As shown, the barrier260desirably contains or includes an opening266extending therethrough and through which opening fluid communication by and between the contents of the first and second chamber262and264can be realized.

The inflator assembly210, similar to the inflator assembly10, has or includes an internal heater270. In accordance with a preferred embodiment, the internal heater270may preferably contain or be composed of a pyrotechnic reactant but other types or forms of heater devices can, if desired, be used in the practice of the invention. As shown, the internal heater is generally disposed inside the storage chamber214, more specifically in the second chamber264.

In accordance with a preferred embodiment of the invention, the barrier260is effective to at least in part limit gas flow communication between the first chamber262and the second chamber264. For example, prior to activation of the magnetic field inductor254, the storage chamber contents216, such as including a gaseous material having magnetic characteristics (such as a paramagnetic oxidant gas source material such as oxygen) and another gas or gases free of magnetic characteristics, such as argon, will over time be in relatively uniform concentration throughout the storage chamber214. However, when the magnetic field inductor254is activated, the oxygen gas will be attracted thereto and thus towards the inflator storage chamber first end222and into the first chamber262. As will be appreciated, upon subsequent inactivation of the magnetic field inductor254, the barrier260can desirably serve to slow or reduce subsequent diffusion or movement of oxygen gas from the first chamber262to the second chamber264.

FIG. 3illustrates an inflator assembly310, in accordance with one preferred embodiment of the invention, and generally similar to the inflator assembly210shown in FIG.2and described above. More particularly, the inflator assembly310, similar to the inflator assembly210, comprises a pressure vessel312that at least in part forms a chamber314, with contents designated by the reference numeral316. The chamber314is generally defined at least in part by an elongated cylindrical sleeve320having a first end322and a second end324. The sleeve first end322is closed by means of an end wall326. The inflator assembly310also includes a wall portion or segment328at least partially closing the sleeve second end324. The wall portion328includes an opening330therein. The opening330is normally closed by sealing means, e.g., such as by means of a burst or rupture disc332such as secured and joined thereto in sealing relation such as is known in the art.

An initiator and diffuser assembly combination334is joined or attached at the sleeve second end324in sealing relation such as by a weld, crimp or other suitable hermetic seal. The initiator and diffuser assembly combination334includes a base wall portion336and a side wall portion340extending therefrom. The initiator and diffuser assembly combination334also defines a diffuser chamber342and includes a plurality of diffuser orifices344, formed in the sidewall portion340, for dispensing inflation gas from the inflator310into an associated inflatable airbag cushion (not shown).

The base wall portion336includes or has an opening348therein, wherethrough an initiator device350is desirably attached in sealing relation, such as via a weld, crimp or other suitable seal. As identified above, suitable initiator devices for use in the practice of the invention may, if desired, include or contain a load of a selected pyrotechnic charge which can be advantageous in providing a large heat input such as may be desired for certain associated reaction processing. The initiator device350includes a discharge end352whereat a discharge formed by the initiator device can be appropriately discharged or otherwise released.

The inflator assembly310also includes a magnetic field inductor354with lead wires356, such as identified above and such as attached at, near to or adjacent the first end322of the elongated cylindrical sleeve320, as detailed below.

The inflator assembly310also includes a barrier360, such as in the form of a bulkhead or the like, positioned within the pressure vessel312and serving to essentially separate the chamber314or otherwise form or create adjacent first and second chambers362and364, respectively. As shown, the barrier360desirably contains or includes an opening366extending therethrough and through which opening fluid communication by and between the contents of the first and second chamber362and364can be realized. Further, as with the inflator assembly210described above, the barrier360is effective to at least in part limit gas flow communication between the first and second chambers.

The inflator assembly310, similar to the inflator assembly210, has or includes an internal heater370. In accordance with a preferred embodiment, the internal heater370may preferably contain or be composed of a pyrotechnic reactant but other types or forms of heater devices can, if desired, be used in the practice of the invention. As shown, the internal heater is generally disposed inside the storage chamber314, more specifically in the first chamber362.

The inflator assembly310primarily differs from the inflator assembly210through the inclusion of a restrictor, here designated by the reference numeral376, adjacent or otherwise in operational communication with the opening366such as to selectively and desirably limit, control or prevent fluid flow communication through the opening366. Suitable restrictors for use in the practice of the invention may take various forms or constructions including: a metallic strip (such as shown in FIG.3); a semi-permeable membrane and a valve such as a standard electro-mechanical valve, for instance. Thus, those skilled in the art and guided by the teachings herein provided will appreciate that the broader practice of the invention is not necessarily limited to use of particular or specific forms or constructions of such flow restrictors.

In such an embodiment, the inflator assembly310works similarly to the inflator assemblies described above in that, as the magnetic field inductor354is energized, the gases separate. In this embodiment, however, upon deactivation of the inductor or, more importantly, firing of the initiator, the restrictor376serves or acts to inhibit or prevent immediate mixing of the entire gas charge. In particular, once the restrictor376has closed, fluid flow communication between the chambers362and364is restricted or prevented. Consequently, separated gases are no longer free to diffuse from the first chamber362to the second chamber364and the internal heater370therein contained. As a result, the effect of separation of the paramagnetic and diamagnetic gases (such as for burn rate modification, for example) can desirably be maintained for a longer or extended period of time. In view thereof, the ability to suitably modify or tailor inflator performance can be significantly enhanced or improved. In accordance with certain preferred embodiments, the restrictor, such as in the form of a thin metallic strip, as shown in FIG.3. will act to impede the mixing of gases, but given a sufficiently strong pressure differential, will open or otherwise allow gases to flow or move between the chambers362and364, through the opening366.

FIG. 4illustrates an inflator assembly, designated by the reference numeral410, in accordance with another preferred embodiment of the invention. The inflator assembly410is generally similar to the inflator assembly310described above. More particularly, the inflator assembly410, similar to the inflator assembly310, comprises a pressure vessel412that at least in part forms a chamber414, with contents designated by the reference numeral416. The chamber414is generally defined at least in part by an elongated cylindrical sleeve420having a first end422and a second end424. The sleeve first end422is at least partially closed by means of a first end wall portion or segment426. The inflator assembly410also includes a second wall portion or segment428at least partially closing the sleeve second end424. The first and second wall portions426and428each includes an opening therein, designated by the reference numerals429and430, respectively. Each of the openings429and430is normally-closed by sealing means, e.g., such as by means of a burst or rupture disc431and432, respectively, such as secured and joined thereto in sealing relation such as is known in the art.

A first initiator and diffuser assembly combination434ais joined or attached at the sleeve first end422in sealing relation such as by a weld, crimp or other suitable hermetic seal. A second initiator and diffuser assembly combination434bis joined or attached at the sleeve second end424in sealing relation such as by a weld, crimp or other suitable hermetic seal. The initiator and diffuser assembly combinations434aand434beach include a base wall portion436aand436b, respectively, and a side wall portion440aand440b, respectively, extending therefrom. Each of the initiator and diffuser assembly combinations434aand434balso defines a diffuser chamber442aand442b, respectively, and includes a plurality of diffuser orifices444aand444b, respectively, formed in the respective sidewall portion440aand440b, for appropriately dispensing inflation gas from the inflator410into an associated inflatable airbag cushion (not shown).

The base wall portions436aand436beach respectively includes or has an opening448aand448btherein, wherethrough a respective initiator device450aand450bis desirably attached in sealing relation, such as via a weld, crimp or other suitable seal. As identified above, suitable initiator devices for use in the practice of the invention may, if desired, include or contain a load of a selected pyrotechnic charge which can be advantageous in providing a large heat input such as may be desired for certain associated reaction processing. The initiator devices450aand450beach respectively includes a discharge end452aand452bwhereat a discharge formed by the initiator device can be appropriately discharged or otherwise released.

The inflator assembly410includes a magnetic field inductor454with lead wires456, such as identified above and such as attached at, near to or adjacent the first end422of the elongated cylindrical sleeve420.

The inflator assembly410also includes a barrier460, such as in the form of a bulkhead or the like, positioned within the pressure vessel412and serving to essentially separate the chamber414or otherwise form or create adjacent first and second chambers462and464, respectively. As shown, the barrier460desirably contains or includes an opening466extending therethrough and through which opening fluid communication by and between the contents of the first and second chamber462and464can be realized. Further, as with the inflator assembly310described above, the barrier460is effective to at least in part limit gas flow communication between the first and second chambers.

The inflator assembly410has or includes a first internal heater470apositioned or otherwise generally disposed within the first chamber462and a second internal heater470bpositioned or otherwise generally disposed within the second chamber464. In accordance with a preferred embodiment, the internal heaters470aand/or470bmay preferably contain or be composed of a pyrotechnic reactant but other types or forms of heater devices can, if desired, be used in the practice of the invention.

The inflator assembly410may, as shown, also include a restrictor476and such as described above, adjacent or otherwise in operational communication with the opening466such as to selectively and desirably limit, control or prevent fluid flow communication through the opening466. As in the above-described embodiment, once the restrictor476has closed, fluid flow communication between the chambers462and464is prevented.

As will be appreciated, different pyrotechnic charges can be used for each of the internal heaters470aand470b. Preferably, the two charges are of different pyrotechnic formulations such as having or resulting in different response to an oxidant gas such as having magnetic characteristics. Those skilled in the art and guided by the teachings herein provided will appreciate that, for example, dependent upon the desired output response, an oxidant gas having magnetic characteristics can be specifically concentrated in the first chamber462or the second chamber464, as may be desired for particular different desired inflation gas outputs. Thus, many different outputs are possible and realizable with an inflator assembly of relatively simple construction and operation.

The inflator assembly410represents one embodiment of an adaptive output inflator configuration that employs or utilizes the magnetic characteristics of gases in accordance with the invention. As such, the inflator assembly410can desirably provide various specific manners of operation and, therefore, many different specific possible inflator performance characteristics. For example, the initiator devices450aand450bcan be selectively individually actuated or fired. Alternatively, the initiator devices450aand450bcan be actuated or fired together or in some staggered sequenced pattern wherein one of the initiator devices450aor450bis first actuated or fired and then the other in the initiator devices is actuated or fired at a selected interval thereafter.

To further illustrate the practice of the invention, specific reference will now be made to a particular mode of operation of the inflator assembly410, such as may be particularly useful or desired in association with a high speed vehicle crash on a hot day such as during which at least certain pyrotechnic materials tend to burn much more rapidly. It is to be understood, however, that the broader practice of the invention is not necessarily limited to such mode of operation and that the invention can desirably be practiced in accordance with other modes of operation dependent on factors such as the factors or conditions associated with the actuation of the inflator assembly.

With actuation of the magnetic field inductor454, a paramagnetic gas is desirably drawn towards the region of high magnetic field strength, in this case the second chamber462. Consequently, upon actuation of the initiator device450a, a relatively lower temperature inflation gas is released from the inflator410, as at least some of the oxygen is unavailable to the pyrotechnic charge of the internal heater470bto permit it to burn rapidly at high temperature. In particular, the restrictor476may desirably serve to limit, control or prevent fluid flow communication through the opening466. Thus, the inflator assembly410provides a first level of inflation performance such as appropriate or desired to decelerate an occupant contacting an airbag cushion inflated thereby.

Since the vehicle, however, was moving rapidly at the time of occurrence of the event necessitating the airbag cushion deployment, the initiator device450bmay desirably be actuated with the pyrotechnic charge of the internal heater470aburning rapidly and high temperature with the available oxygen. Consequently, gas mass flow rate is increased, providing more gas more quickly to an associated airbag cushion, to further decelerate the occupant coming into contact with the airbag cushion in inflation communication therewith.

As will be appreciated, magnetic field inductors can desirably be turned on or off such as to consequently result in a timely desired non-uniform magnetic field. Thus, in accordance with one preferred embodiment of the invention the desired non-uniform magnetic field can be done or realized on demand. In practice, the actuation of the magnetic field inductor (and magnetic field strength) can desirably employ a safety restraint control system such as composed of a computer system such as used in the management of parameters such as temperature, vehicle speed, occupant position, occupant weight, seat belt usage, seat position, etc.

Further, while the invention has been described above making specific reference to embodiments wherein the magnetic field inductor is turned on or off such as to consequently result in a non-uniform magnetic field, those skilled in the art and guided by the teachings herein provided will appreciate that the broader practice fo the invention is not necessarily so limited. For example, the invention can, if desired, be practiced by simply desirably changing the magnetic field strength such as to desirably result in particular gas separation.

In view of the above, it will be appreciated that the invention provides a novel adaptive output inflator device and method which may desirably facilitate the selectively variable supply of inflation medium to an airbag such as may be necessary to protect the vehicle occupant.

Thus, the invention provides an improved inflation system and method of operation such as may improve one or more of the safety, simplicity, effectiveness, economy, and reliability thereof, particularly as applied to adaptive inflation systems and operation. More specifically, the invention provides such an improved inflation system and method of operation wherein the magnetic characteristics of an inflation medium gas are employed to selectively vary the inflation characteristics of an inflator device.