Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B60—VEHICLES IN GENERAL
  • B60R—VEHICLES, VEHICLE FITTINGS, OR VEHICLE PARTS, NOT OTHERWISE PROVIDED FOR
  • B60R21/00—Arrangements or fittings on vehicles for protecting or preventing injuries to occupants or pedestrians in case of accidents or other traffic risks
  • B60R21/02—Occupant safety arrangements or fittings, e.g. crash pads
  • B60R21/16—Inflatable occupant restraints or confinements designed to inflate upon impact or impending impact, e.g. air bags
  • B60R21/26—Inflatable occupant restraints or confinements designed to inflate upon impact or impending impact, e.g. air bags characterised by the inflation fluid source or means to control inflation fluid flow
  • B60R21/268—Inflatable occupant restraints or confinements designed to inflate upon impact or impending impact, e.g. air bags characterised by the inflation fluid source or means to control inflation fluid flow using instantaneous release of stored pressurised gas

Definitions

• the present invention relates to inflators used to inflate air bags in an automobile occupant protection system and, more particularly, to a mechanism for releasably containing a pressurized inflation fluid i a container used in a stored gas i ⁇ flator.
• Inflation systems for deploying an air bag in a motor vehicle generally employ a gas generator in fluid communication with an uninflated air bag.
• the gas generator is typically triggered by a firing circuit when a sensor determines that vehicle acceleration has exceeded a predetermined threshold value (for example, through the use of an acceleration-responsive inertial switch.)
• Air bag inflation systems often utilize a stored gas generator (or hybrid gas generator) housed within the B-pillar of a car, for example.
• Stored gas generators contain pressurized gas that is released to inflate the airbag upon receipt of a predetermined signal from the sensor.
• An ongoing challenge is to reduce the time required to release the stored gas upon a crash event.
• improved safety and reduced manufacturing costs are also ongoing concerns. Improvements in any of these areas would provide an advantage over state-of-the-art gas release systems.
• a mechanism for releasably confining pressurized fluid in a container includes a rupturable membrane (for example, a burst disk) in is fluid communication with an interior of the container, thereby exposing the membrane to the fluid.
• the membrane is configured to obstruct flow of the pressurized fluid when externally supported against pressure exerted by the fluid.
• the membrane is also rupturable by pressure exerted by the fluid when not externally supported against the pressure exerted by the fluid.
• a support member is provided for externally supporting the membrane against pressure exerted by the fluid. The support member is configured to be fracturable upon exposure to combustion products formed by activation of a gas generator.
• the mechanism described above may be incorporated into an inflator which includes a pressurized gas bottle having an opening which is sealed prior to activation of a gas generator, and a housing coupled to the gas bottle over the opening.
• the housing defines a gas passage, and has a first end, a second end, and a longitudinal axis extending between the first and second ends.
• the support member is fixed within the passage and is positioned over the bottle opening prior to gas generator activation to prevent gas flow through, the housing passage.
• a gas generator is coupled to the housing and is spaced apart from the longitudinal axis. The gas generator is positioned so as to fluidly communicate with the support member upon gas generator activation.
• FIG. 1 is a cross-sectional view of an inflator incorporating a mechanism for releasably confining pressurized fluid in a container, in accordance with the present invention
• FIG. 2 is a partial cross-sectional view of a container for storing pressurized inflation fluid in accordance with the present invention
• FIG. 3 is an end view of the container shown in FIG. 2
• FIG. 4 is a cross-sectional view of a housing used in the embodiment of the mechanism for releasably confining pressurized fluid in a container interior shown in FIG. 1
• FIG. 5 is an enlarged view taken with the circle 5 of FIG.
• FIG. 6 is a cross-sectional view of the inflator shown in FIG. 1 showing fracturing of a support member during operation of the inflator
• Fig. 7 is a schematic view of an airbag system and a vehicle occupant restraint system incorporating an inflator using the pressurized fluid containment mechanism of the present invention.
• FIGS. 1-6 show one embodiment of an inflator 8 incorporating a mechanism 10 for releasably containing pressurized fluid in a container, in accordance with the present invention.
• mechanism 10 is shown secured to a gas bottle or tank 18 in which a pressurized fluid (in this case, an inflation gas) is stored.
• Bottle 18 has an annular wall 36 defining an opening 24, with an annular shoulder 37 extending from annular wall 36 to form an annular ledge 26 along a base portion of shoulder 37.
• mechanism 10 includes a rupturable membrane 22 (for example, a burst disk) secured in fluid communication with an interior of bottle 18.
• a rupturable membrane 22 for example, a burst disk
• Membrane 22 forms a fluid-tight barrier preventing flow of pressurized gas through or around the membrane.
• membrane 22 is seated along gas bottle annular ledge 26 and -welded or otherwise secured thereon to obstruct flow of the pressurized fluid during normal vehicular operation.
• Membrane 22 is configured to obstruct flow of the pressurized fluid when externally supported against pressure exerted by the fluid by a support member 28, as described in detail below.
• Membrane 22 is also configured to be rupturable by pressure exerted by the fluid when not externally supported against this pressure.
• Membrane 22 may be stamped or formed from any of various disks, foils, films, etc., as is known in the art.
• a support member 28 abuts membrane 22 to bias the membrane against ledge 22, thereby providing external support to the membrane against pressure exerted by fluid stored in bottle 18.
• support member 28 is tapered from a first end 32 to a second end 34.
• First end 32 has a diameter slightly larger than a diameter of annular ledge 26 formed in bottle wall 26 adjacent bottle opening 24. Accordingly, support member first end 32 forms an interference fit with shoulder 37 to cover membrane 22.
• Support member 28 may be formed from a polymeric material that decomposes in the presence of heat and, as explained below, also fractures upon contact with, gases resulting from combustion of a gas generant compound.
• support member 28 may be made from a two-part epoxy resin.
• the epoxy or polymeric composition used to form the support member 26 may be obtained, for example, from ITW Devcon of Danvers, MA under the trade name "5-Minute Epoxy Resin".
• the primary constituents of the epoxy resin include bisphenol A diglycidyl ether resin in an amount greater than 60% by weight.
• the "5- Minute Epoxy Resin” may be employed with a “5-Minute Epoxy Hardener", also provided by ITW Devcon of Danvers, MA.
• the primary constituents of the epoxy hardener include a mercaptan amine blend in an amount preferably ranging from 90-100% by weight.
• Other two-part epoxy compositions include, but are not limited to, "Epoxy Plus Resin” and "Epoxy Plus Hardener” also provided by ITW Devcon.
• the resin composition includes aminoethylpiperazine at about 10-30% by weight of the total composition, nonylphenol at about 10-20% by weight of the total composition, polyamide of C18 fatty acid dimmers and 1,4,8,11- tetraazacyclotetradecane-N,N,N",N'"-tetraacetic acid (TETA) at about 1-5% by weight of the total composition, and 2,4,6-Tris(Dimethylaminomethyl)phenol at about 5-10% by weight of the total composition.
• TETA 1,4,8,11- tetraazacyclotetradecane-N,N,N",N'"-tetraacetic acid
• the hardener composition includes bisphenol A diglycidyl ether resin at about 30-60% by weight of the total composition, an acrylate at about 1-5% by weight of the total composition, and butylated bisphenol A epoxy resin at about 30-60% by weight of the total composition.
• Other suitable two-part epoxies or polymers are also contemplated.
• support member 28 is fixed within a passage 11 formed in an elongated housing 12 secured to container 18.
• Housing 12 contains a first end 14, a second end 16, and passage 11 for receiving the pressurized fluid therethrough. Passage 11 extends between housing first end 14 and housing second end 16.
• a connecting passage 13 in communication with passage 11 is formed in housing 12 to enable fluid communication between passage 11 and a gas generator, as described in greater detail below.
• Housing 12 is fabricated (for example, by stamping, casting, forming, or some other, suitable process) from a rigid material such as carbon steel or stainless steel.
• passage 11 is tapered to conform to the shape of support member 28, as described above. This enables housing 12 to brace support member 28 i a position abutting membrane 22. Shaping passage 11 in correspondence with a desired shape of support member 28 also enables the housing to be used as a mold, or vessel, to fabricate the support member within the housing.
• Support member 28 may be formed within housing 12 by injecting or pouring an epoxy compound into a portion of housing 12 machined or formed to the desired shape of support member 28. In the case where support member 28 is formed within housing 12, the epoxy is positioned in the housing according to manufacturer instructions and then cured within housing 12. Alternatively, Support member 28 may be preformed and inserted into housing 12 during assembly of mechanism 10. In an alternative embodiment (not shown), the support member is secured to a part of the assembly other than the housing (for example, to bottle 18). In another alternative embodiment (not shown), rather than securing membrane 22 to bottle 18, membrane 22 is secured within housing passage 11. In yet another alternative embodiment (also not shown), membrane 22 is secured to housing 12 outside passage 11. Referring again to FIG.
• a gas generator 66 is positioned in relation to housing 12 so as to enable fluid communication with support member 28 upon activation of the gas generator.
• gas generator 66 is crimped or otherwise suitably secured to the periphery of housing 12 and extends through a wall of the housing so that, upon activation of gas generator 66, the gas generator is in fluid communication with passage 11 via connecting passage 13.
• membrane 22 and support member 26 lay along a common axis L extending between the housing first end 14 and housing second end 16. It may also be seen that gas generator 66 is spaced apart from axis L. Stated another way, gas generator 66 does not intersect axis L along which membrane 22 and support member 28 are positioned.
• axis is understood to designate a line in relation to which parts of a structure or body may be referenced.
• An igniter 68 is contained within the generator 66 and ignitably communicates with a gas generant 70 also contained within generator 66.
• Gas generant 70 may comprise any gas generant composition known for its utility in vehicle occupant protection systems.
• Co-owned U.S. Patent Nos. 5,035,757, 5,756,929, 5,872,329, 6,077,371, 6,074,502, and 6,210,505 are incorporated herein by reference and exemplify, but do not limit gas generant compositions contemplated in accordance with the present invention.
• gas generant 70 comprises a mixture of silicone as a fuel at about 10-25% by weight, and an oxidizer such as ammonium or potassium perchlorate at about 75-90% by weight. Silicone not only functions as a fuel but also functions as a binder thereby facilitating the formation of pliant cylindrical gas generant extrusions.
• gas generant 70 comprises silicone as a fuel at about 10-25% by weight; a perchlorate oxidizer such as ammonium, lithium, or potassium perchlorate; and a strontium salt such as strontium nitrate or strontium carbonate as a coolant, wherein the oxidizer and coolant comprise about 75-90% by weight of the gas generant.
• gas generant composition 70 comprises, in percents by weight, 10-25% silicone, 75-90% oxidizer, 1-30% coolant, and 1-20% of a slag- forming constituent.
• the oxidizer may be selected from, for example, inorganic perchlorates and nitrates such as sodium perchlorate, potassium perchlorate, ammonium perchlorate, potassium nitrate, ammonium nitrate, and phase stabilized ammonium nitrate.
• the coolant may, be selected from for example metal hydroxides such as aluminum hydroxide; metal carbonates such as calcium carbonate, magnesium carbonate, strontium carbonate, and sodium carbonate; and inorganic oxalates such as calcium oxalate, strontium oxalate, and ammonium oxalate.
• the slag-forming constituent may be selected from for example metal oxides such as aluminum oxide and iron oxide. It has been found that gas generating compositions containing silicone and a perchlorate oxidizer burn at relatively lower temperatures when a coolant, in accordance with the present invention, is added to the mixture. As a result, the cooling requirements of gas generated within the mechanism 10 can be substantially minimized while still providing sufficient heat to fracture and decompose the support member 26.
• a hollow diffuser 44 is machined or otherwise formed from steel or other suitable materials, and then welded or otherwise fixed to housing second end 16. Diffuser 44 functions to distribute gas flowing from first end 14 through passage 11 to housing second end 16.
• a plurality of gas discharge orifices 54 is spaced about a circumference of the diffuser. The embodiment shown in FIGS. 1 and 5 includes four gas discharge orifices 54 evenly spaced about the circumference of the diffuser.
• the diffuser may incorporate a filter 45 therein to filter combustion products and fragments of support member 28 from the inflation fluid prior to gas distribution. Any suitable metallic mesh filter or woven wire cloth may be used, many examples of which are known and obtainable from commercially available sources (for example, Wayne Wire Cloth Products, Inc.
• the igniter 68 receives a signal from a crash sensor or accelerometer (not shown), for example, and then ignites gas generant 70.
• Heat and combustion gases produced by ignition of gas generant 70 proceed along connecting passage 13 to passage 11 where supporting member 26 is positioned.
• the heat and combustion products are directed toward axis L upon activation of gas generator 66.
• the combustion products are directed along a line substantially orthogonal to axis L.
• heat and combustion products from the gas generator are directed generally toward where support member 26 resides, although not necessarily along a straight line or along a line orthogonal to axis L.
• Airbag system 200 includes at least one airbag 202 and an inflator 8 coupled to airbag 202 so as to enable fluid communication with an interior of the airbag.
• Airbag system 200 may also be in communication with a crash event sensor 210 including a known crash sensor algorithm that signals actuation of airbag system 200 via, for example, activation of airbag igniter 68 in the event of a collision.
• a crash event sensor 210 including a known crash sensor algorithm that signals actuation of airbag system 200 via, for example, activation of airbag igniter 68 in the event of a collision.
• an embodiment of the inflator or an airbag system including an embodiment of the inflator may be incorporated into a broader, more comprehensive vehicle occupant restraint system 180 including additional elements such as a safety belt assembly, as seen in FIG. 7.
• Safety belt assembly 150 includes a safety belt bousing 152 and a safety belt 160 in accordance with the present invention extending from housing 152.
• A. safety belt retractor mechanism 154 (for example, a spring-loaded mechanism) may be coupled to an end portion 153 of the belt.
• a safety belt pretensioner 156 may be coupled to belt retractor mechanism 154 to actuate the retractor mechanism in the event of a collision.
• Typical seat belt retractor mechanisms which may be used in conjunction with the safety belt embodiments of the present invention are described in U.S. Pat. Nos. 5,743,480, 5,553,803, 5,667,161, 5,451,008, 4,558,832 and 4,597,546, incorporated herein by reference.
• Illustrative examples of typical pretensioners with which the safety belt embodiments of the present invention may be combined are described in U.S. Pat. Nos. 6,505,790 and 6,419,177, incorporated herein by reference.
• Safety belt system 150 may be in communication with a crash event sensor 158 (for example, an inertia sensor or an accelerometer) including a known crash sensor algorithm that signals actuation of belt pretensioner 156 via, for example, activation of a pyrotechnic igniter (not shown) incorporated into the pretensioner.
• a crash event sensor 158 for example, an inertia sensor or an accelerometer
• U.S. Pat. Nos. 6,505,790 and 6,419,177 previously incorporated herein by reference, provide illustrative examples of pretensioners actuated in such a manner.

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• Physics & Mathematics (AREA)
• Fluid Mechanics (AREA)
• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Air Bags (AREA)
• Feeding, Discharge, Calcimining, Fusing, And Gas-Generation Devices (AREA)

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Applications Claiming Priority (4)

Publications (2)

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Citations (9)

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• 2004
  • 2004-10-20 US US10/969,254 patent/US7527290B2/en not_active Expired - Fee Related
  • 2004-10-21 WO PCT/US2004/035341 patent/WO2005039893A2/en not_active Ceased
  • 2004-10-21 EP EP04817358A patent/EP1677995A4/en not_active Withdrawn
  • 2004-10-21 JP JP2006536899A patent/JP2007517705A/ja active Pending

Patent Citations (10)

Non-Patent Citations (1)

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