JP2008201404A - Gas generating system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To establish a lightweight, low-cost gas generating system having a filter for cooling the produced gas. <P>SOLUTION: The filter is provided including a first layer 200 of sheet material having a first base portion, and a plurality of first raised portions extending from the first base portion and defining a corresponding plurality of first openings through the first layer 200. A second layer 201 of sheet material also has a second base portion and a plurality of second raised portions extending from the second base portion and defining a corresponding plurality of second openings through the sheet material. The second layer 201 of sheet material is positioned adjacent to the first layer 200 of sheet material such that the first raised portions extend from the first base portion toward the second layer 201, and the second raised portions extend from the second base portion toward the first layer. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

This application claims the benefit of provisional application No. 60 / 876,418, filed on December 20, 2006.

TECHNICAL FIELD The present invention relates generally to gas generation systems or inflators used in inflatable occupant restraint systems in automobiles. More particularly, the present invention relates to a gas generation system or an inflator having a filter for cooling the generated gas.

BACKGROUND OF THE INVENTION As standard equipment in all new vehicles, the installation of inflatable occupant restraint systems, commonly known as “airbags”, has enhanced the search for smaller, lighter and cheaper occupant restraint systems. ing. Inflators used in such systems tend to be the heaviest and most expensive and there is a need for lighter and cheaper inflators.

  A typical inflator has a cylindrical steel or aluminum housing having a diameter and length associated with a vehicle application and includes a propellant therein. The inflator is generally provided with an internal filter that includes one or more layers of expanded metal or steel screen with different wire diameters from the mesh. The gas produced upon combustion of the propellant is passed through a filter before leaving the inflator. Particulate matter or slag produced during propellant combustion in known systems is substantially removed as the gas passes through the filter.

  Known filter / heat sink designs are formed from compressed and bonded wire or expanded metal and remove heat with a thermal mass. However, these known filter compositions and structures act to increase the weight of the filter and reduce the uniformity and controllability of gas flow, thereby increasing the variability of ballistic properties.

SUMMARY OF THE INVENTION In one aspect of the present invention, a filter has a first layer of sheet material having a first base portion, and a plurality of firsts extending from the first base portion and corresponding through the first layer. Provided with a plurality of first protruding portions defining a plurality of openings. A second layer of sheet material is provided having a second base portion and a plurality of second protruding portions extending from the second base portion and defining a corresponding plurality of second openings through the sheet material. Is done. A second layer of sheet material is disposed adjacent to the first layer of sheet material, and a first protruding portion extending from the first base portion extends in the direction of the second layer and extends from the second base portion. The extending second protruding portion extends in the direction of the first layer.

DETAILED DESCRIPTION The present invention generally relates to an inflator or gas generator that uses a filter formed from a continuous layer of embossed sheet material that defines a series of tortuous flow paths for the generated gas. Includes the system. The embossed type filter removes heat from the gas as it travels through the tortuous path formed by the embossed design. The selection of a suitable gas generant composition that can generate and burn an inflation gas that does not contain an inappropriate amount of particulates further avoids the need for the known relatively heavy wire mesh filter. The avoidance of the need for known filters in the inflator allows a device that is simpler, lighter, less expensive and easier to manufacture.

  1 and 2 show cross-sectional views of a first embodiment of a gas generation system 10 of the present invention. The gas generation system 10 is preferably made from a member made from a strong metal such as carbon steel or iron, but can include a member made from a tough, impact resistant polymer, for example. Those skilled in the art will understand the various manufacturing methods for the various components of the gas generation system.

  Reference is made to FIGS. The gas generation system 10 includes a generally cylindrical housing 12 having a closed end 14, an open end 16, and an outer wall 18 that extends along a longitudinal axis “A”. The housing 12 can be cast, stamped, extruded, or otherwise metal formed. At least one and preferably a plurality of openings 20 are formed along the housing wall 18 to allow fluid communication between the interior of the gas generation system and an airbag or other inflatable device (not shown).

  To prevent water vapor from entering the gas generation system housing 12, the opening 20 can be covered with a foil 56, such as an aluminum or stainless steel foil. The foil 56 is often referred to as a “burst foil” and is typically from 0.01 to about 0.20 mm thick. The foil 56 is typically adhered to the inner surface of the gas generating system housing using an adhesive.

  The gas generating system housing lid 30 is secured to the open end 16 of the housing 12 by crimping, welding or otherwise. The lid 30 can be cast, stamped, or otherwise metal molded. Alternatively, the lid 30 can be molded from a suitable high temperature resistant polymer.

  The gas generation system 10 further includes a first inflation fluid source disposed within the outer wall to releasably inflate the inflation fluid to inflate an inflatable element of a vehicle occupant restraint system, such as an airbag. Store, produce, or otherwise provide. In the embodiment shown in FIGS. 1 and 2, the first inflation fluid source is a gas generator disposed in a combustion chamber 24 defined by a filter 58 (described in detail below) and an end closure 30. Composition 22 is included.

  The gas generant 22 can be any known, smokeless gas generant composition useful in airbag applications, such as US Pat. Nos. 5,035,757, 5,872. 329, 6,074,502, 6,287,400, 6,306,232, 6,475,312, but are not limited thereto. These patents are referenced and incorporated as part of this specification. Other suitable compositions are disclosed in US patent application Ser. Nos. 10 / 407,300 and 60 / 369,775, which are incorporated by reference and incorporated herein. As used herein, the term “smokeless” should be generally understood to mean a propellant capable of providing at least about 90% of a gaseous product as a combustion product based on the sum of the product materials; Also, as a reasoning, the solid product is about 10% or less based on the total amount of product. It has been found that the use of compositions having the disclosed combustion characteristics can generally eliminate filters as used in other gas generation system designs.

  The igniter 26 is securely attached to the gas generating system 10 and allows fluid communication with the gas generant 22 to ignite the gas generant in the event of a collision. In the embodiment shown in FIGS. 1 and 2, the igniter 26 is placed and securely attached within the annular bore of the housing lid 30 using known methods. In a different embodiment (not shown), the perforated igniter support tube can be welded or otherwise secured within the housing 12 to support the igniter 26. The perforated support tube allows the frame front generated by the igniter 26 to pass to the gas generant 22, thereby igniting the gas generant and generating inflation gas. The igniter 26 can be formed as is known in the art. One exemplary igniter structure is described in US Pat. No. 6,009,809, which is incorporated by reference and incorporated herein.

  Please refer to FIGS. 1 and 2 again. A predetermined amount of a known booster propellant 28 may be disposed within the housing 12 to allow fluid communication between the booster propellant and the gas generant composition 22 upon activation of the gas generant system. A cup 25 can be placed in the gas generation system housing to enclose the igniter 26 and receive the booster propellant 28. The cup 25 can be metal formed by stamping, extrusion or other methods, and can be made from carbon steel, stainless steel or other thermally conductive metals or alloys. Activation of the igniter 26 causes combustion of the booster propellant, thereby igniting the gas generant composition 22 in a manner known in the art. In addition, a cavity can be formed in the end surface of the booster cup to accommodate a predetermined amount of thermally activated autoignition compound 29.

  A self-ignition compound 29 can be disposed in the gas generation system to allow fluid communication between the gas generant 22 and the self-ignition compound and / or further fluid between the booster propellant 28 and the self-ignition compound. Can be contacted. In a manner known in the art, ignition of the gas generant 22 is caused by the combustion of the booster propellant 28 resulting from the combustion of the autoignition compound 29. Alternatively, ignition of the gas generant 22 can be caused by the combustion of the self-ignition compound 29 directly. The autoignition material 29 is ignited by exposure to a temperature below the ignition temperature of the gas generant 22 in response to exposure outside the gas generant system housing to high temperatures (eg, caused by a vehicle fire). It is a substance. When ignited, the autoignition material 29 produces a hot gas / particulate effluent. Suitable autoignition materials are known to those skilled in the art. Examples of suitable autoignition materials are nitrocellulose-based compositions and black powder. The combustion of the gas generant 22 can also be initiated by the combustion of the booster propellant 28 without using a self-igniting material.

  Please refer to FIGS. 1 and 2 again. The gas generation system of the present invention uses a filter, generally designated 58, to pass inflation fluid between the combustion chamber 24 and the outer wall 18 and to cool the inflation gas passing therethrough. The filter 58 is operatively disposed between the gas generant composition 22 and the housing wall 18. That is, the filter 58 is configured such that the expansion fluid generated by the combustion of the gas generant 22 passes through the filter to reach the housing wall 18.

  Generally, the filter 58 has a first layer of sheet material having a first base portion, and a plurality of first protruding portions extending from the first base portion, the protruding portions corresponding to the first layers. A plurality of first openings are defined through the layers. The second layer of sheet material has a second base portion and a plurality of second protruding portions extending from the second base portion, the protruding portions corresponding to a plurality of second openings through the sheet material. Define the part. A second layer of sheet material is disposed adjacent to and securely attached to the first layer of sheet material, and a first protruding portion extending from the first base portion extends in the direction of the second layer, A second protruding portion extending from the base portion extends in the direction of the first layer.

  In the embodiment shown in FIGS. 1 and 2, the filter 58 is formed from two cylindrical layers 200, 201 of embossed sheet material. The sheet material can be aluminum, steel or any suitable metal that can be formed into a shape having the desired characteristics by embossing or a similar process. Molding can be, for example, by pressing with a roller, a complementary mold, punching or other methods. The material used in the sheet can have a relatively high thermal conductivity in order to more efficiently absorb heat from the generated gas and transfer heat. In certain embodiments, sheets 200 and 201 are substantially coaxial.

  In the embodiment shown in FIGS. 1-2, the embossed pattern is formed in the structure of the sheets 200 and 201. Layers 200 and 201 include corresponding base portions 200a and 201a, and include portions of embossed first and second protruding portions 200b and 201b that are spaced apart. The protruding portions 200b, 201b extend from the corresponding base portions 200a, 201a of each sheet and define openings 200c, 201c extending through the respective layers. These openings direct the gas flow in a direction substantially perpendicular to the base portion of the sheet material, the direction indicated by arrows B and C.

  As seen in FIG. 1-2, the sheets 200 and 201 are arranged adjacent to each other, and the first protruding portion 200b on the first layer 200 is opposite to the base portion 201a of the second layer 201; A clearance 202a is formed between the first protruding portion 200b and the second layer base portion 201a. These clearances provide a corresponding plurality of fluid flow paths between the first protruding portion 200b and the second base portion 201a. Similarly, the second projecting portion 201b on the second layer 201 is spaced from the base portion 200a of the first layer 200, and is spaced from the second projecting portion 201b and the first layer. A clearance 202b is formed between the base portion 200a. These clearances provide a corresponding plurality of fluid flow paths between the second protruding portion 201b and the first base portion 200a.

  In the embodiment shown here, the protruding portion on one layer is opposite the base portion of the other layer. This is because the protrusions of one layer are nested between the protrusions of another layer, thereby creating a space between the protrusions of another layer.

  As shown in FIG. 2, these nested embossed patterns work with the base portions 200a, 201a of the sheet material to define multiple tortuous gas flows through the thickness of the filter. A typical path for the generated gas through the filter is indicated by arrows B and C in FIG.

  The spacing between layers 200 and 201 necessary to provide clearance 202a, 202b can be formed using any of a number of methods. For example, as shown in FIG. 2, one or more spacer portions 211 can be formed in the base portion of one or both sheets, and other sheets when the sheets are placed adjacent to each other. It can touch the base part. Alternatively, any of a variety of other methods (eg, individual stand-alone spacers) can be used to achieve the relative placement of sheets 200 and 201 to provide clearance 202.

  In another embodiment 158 of the filter (shown in FIG. 3), a porous layer 210 of filter or other material is applied to one or both sheets prior to the formation of the protruding portions 200b, 201b and the openings 200c, 201c. 200, 201 applied to the inner surface. In FIG. 3, the filter material 210 is applied only to the layer 201. The formation of the protruding portion 201b during manufacture of the sheet cuts or otherwise opens the corresponding opening through the filter material 210, while the rest of the filter material applied to the base portion 201a is kept intact. ing. As can be seen in FIG. 3, when the sheets 200 and 201 are arranged adjacent to each other, the complete portion of the filter material 210 abuts the end of the protruding portion 200b, thereby filtering the corresponding plurality of fluid flow passages. Provide in the layer of material. Thus, the gas through layers 200 and 201 further passes through the porous material supplemental layer 210 to provide additional filtration of the gas.

  In certain embodiments, the thickness of the filter material 210 provides the spacing between the layers 200 and 201 that is required to form the clearances 202a and 202b.

  4A and 4B further illustrate another embodiment filter 258. In this embodiment, the embossed raised portions 300b, 301b define openings through the corresponding layers 300 and 301. This directs gas flow in a direction substantially parallel to the respective base portion 300a, 301a of the sheet material, which is the direction indicated by the arrow “E”. In this embodiment, the distance d that the protruding portions 300b, 301b extend over the respective base portions 301a and 301b is substantially equal. Also, the distance between the base portion 300a of the first layer 300 and the base portion 301a of the second layer 301 is determined by the distance d. The protruding portions 300b, 301b in FIGS. 4A and 4B each provide a single opening 310 for the flow of gas therethrough. 4B is a partial cross-sectional view of the filter shown in FIG. 4A viewed from the direction of arrow F in FIG. 4A. FIG. 4B shows that the gas exits through the opening 310 formed in the protruding portion 300 b of the layer 300 and enters the opening formed in the protruding portion 301 b of the layer 301. In certain embodiments (not shown), the protruding portion includes a plurality of openings therein to provide a plurality of gas flow paths through the protruding portion. For example, an opening can be provided along the opposite side of each projection portion to allow gas to exit (enter) the projection portion and enter (exit) the opposite projection portion.

  By controlling properties such as the size of the protrusion opening and / or the spacing between the protrusion extending from one layer and the base of another layer, the gas flow rate, the path of the gas through the filter Characteristic parameters such as length, heat conduction from the gas and other parameters can be affected.

  Although two sheets or layers of sheet material are shown in the above embodiments of the present invention, any desired number of embossed sheets can be applied to the desired performance characteristics, such as gas residence time in the filter, average through the filter. It can be used to optimize properties such as gas flow path length and heat conduction from the gas. Further, while the above embodiments use an annular sheet, a series of substantially flat sheets, folded sheets, or sheets made into other desired structures can be used for specific gas generation system design requirements. Can be used according to.

  If desired, known compressed and bonded wires, expanded metal, other types of filter elements or materials, along with embossed filter components, may be used for additional filtration capacity or additional gas cooling capacity. May be used to provide additional heat mass. Such a filter element may be, for example, one or more filter materials disposed between the gas generant combustion chamber and the filter, between the layers of sheet material containing the filter, and / or along the outside of the filter. Can do.

The operation of the gas generation system is discussed with reference to FIGS.
In FIG. 1, at least a portion of the opening through the first layer 200 is in fluid communication with the combustion chamber 24 of the gas generation system. Upon collision, a signal from a crash sensor (not shown) is transmitted to the igniter 26, thereby actuating the booster propellant 28. Heat from the combustion of the booster propellant 28 causes the gas generant 22 to ignite. As indicated by arrows B and C (FIG. 2), the gas produced by the combustion of the gas generant 22 passes through an embossing pattern formed in successive layers 200 and 201 of sheet material. As mentioned above, if it is necessary to provide additional cooling performance, an additional embossed sheet or known wire mesh or expanded metal filter element is also provided in the gas chamber formed in the combustion chamber and gas generation system housing. It can arrange | position between opening parts. However, the use of embossed filter components generally avoids the need to use relatively heavier known filter elements in order to perform the necessary cooling function. Thus, the overall weight of the gas generation system is substantially reduced.

  In the embodiment shown in FIG. 1-2, the expanded gas produced by the combustion of the gas generant 22 proceeds radially outward through the filter 58 and formed between the filter 58 and the wall of the housing 12. Enters into the planum 64 and flows through the filter 58 in the direction indicated by arrows B and C. The inflation gas then flows out of the housing through the opening 20 and into an associated airbag (not shown). The tortuous fluid flow pattern established by the embossed pattern and slits formed in the continuous layer of sheet material is believed to provide a predetermined degree of cooling of the inflation fluid. With appropriate improvements in factors such as the geometry of the embossed pattern and the number and location of slits, the degree of fluid cooling can be correspondingly adjusted to meet the cooling requirements in a specific application.

  FIG. 5 illustrates a specific application of the gas generation system structure of the embodiment described above. Please refer to FIG. The gas generation system including the filter is incorporated into a driver side airbag module 100 mounted in a vehicle steering column. Embodiments of the airbag module 100 or any gas generation system described herein include a wider, more comprehensive vehicle occupant restraint system 180 that includes additional elements such as a safety belt assembly 150. Can be incorporated. FIG. 5 shows a schematic diagram of one exemplary embodiment of such a restraint system. The airbag module 100 includes or is connected to an airbag 202 and a collision sensor 210. The crash sensor 210 is connected to a known crash sensor algorithm that generates a signal for activation of the airbag module 100 in the event of a crash, for example by activation of the igniter 26 (FIG. 1).

  Safety belt assembly 150 includes a safety belt housing 152 and a safety belt 225 of the present invention extending from housing 152. A safety belt retractor mechanism 154 (eg, a spring-loaded mechanism) can be coupled to the belt end portion 153. Further, a safety belt pretensioner 156 can be coupled to the belt retractor mechanism 154 to start the retractor mechanism in the event of a collision. Exemplary seat belt retractor mechanisms that can be used with the safety belt embodiment of the present invention are US Pat. Nos. 5,743,480, 5,553,803, 5,667,161, 5,451,008, 4,558,832 and 4,597,546. These patents are referenced and incorporated as part of this specification. Examples of typical pretensioners with which safety belt embodiments of the present invention can be combined are disclosed in US Pat. Nos. 6,505,790 and 6,419,177. These patents are referenced and incorporated as part of this specification.

  The safety belt system 150 includes a crash sensor algorithm 158 (e.g., a known crash sensor algorithm that generates an activation signal for the belt pretensioner 156, e.g., upon activation of a pyrotechnic igniter (not shown) incorporated in the pretensioner. Inertial sensors or accelerometers) or can be connected thereto. US Pat. Nos. 6,505,790 and 6,419,177, referenced above and incorporated as part of this specification, provide examples of pretensioners that start in such a manner.

  The embossed sheet filter design described herein provides several advantages over known filter designs. Since all or at least a portion of the filter is formed from a continuous layer of relatively light sheet material, the weight of the filter and gas generating system is reduced. Embossed sheet materials are relatively simpler and less expensive to manufacture than known filter materials. The embossed pattern formed in the filter sheet material also allows greater control over the filter shape. Thus, the shape and length of the gas flow path can be defined with greater accuracy, more uniform gas flow through the filter, greater residence time of gas in the filter, contact between gases, and the filter provided. It allowed a larger area of filter material for the total thickness, increased system performance and reduced changes in ballistic properties.

  Further, it is believed that the advantages in filters formed in accordance with the present invention will provide similar advantages with respect to airbag modules and generally vehicle occupant restraint systems. These advantages include, for example, low gas outlet temperature, ease of manufacture, reduced manufacturing costs, simplified assembly, and tailored suitability of the combined airbag inflation profile.

  It will be further understood that the foregoing descriptions of embodiments of the present invention are for illustrative purposes only and do not limit the scope of the invention in any way. As such, the various structural operational features shown herein can be modified in many ways by those skilled in the art without departing from the scope of the invention as defined by the claims. .

FIG. 1 is a cross-sectional view of a gas generation system incorporating a first embodiment of the filter of the present invention. FIG. 2 is an enlarged partial cross-sectional view of the filter portion of FIG. FIG. 3 is a partial cross-sectional view of a filter according to another embodiment of the present invention. FIG. 4-A is a partial cross-sectional side view of a filter according to another embodiment of the present invention. FIG. 4-B is a partial cross-sectional view of the filter embodiment shown in FIG. 4-A. FIG. 5 is a schematic diagram of an exemplary vehicle occupant restraint system incorporating a gas generation system including a filter of the present invention.

Claims (11)

A sheet material having a first base portion and a plurality of first protrusion portions extending from the first base portion, wherein the protrusion portions define a plurality of first openings through corresponding first layers. First layer;
A second sheet material having a second base portion and a plurality of second protrusion portions extending from the second base portion, the protrusion portions defining a plurality of second openings through the corresponding sheet material. A filter comprising:
A second layer of the sheet material is disposed adjacent to the first layer of sheet material, a first protrusion extending from the first base portion extends toward the second layer, and a second base A filter, wherein a second protruding portion extending from the portion extends toward the first layer. The distance between the base portion of the first layer and the base portion of the second layer is the distance between the first layer and the protruding portion of the second layer extending from one of the first layer and the second layer. The filter of claim 1, determined by: The filter of claim 1 further comprising a layer of filter material disposed between the first and second layers of sheet material. The first protrusion portion is spaced relative to the second base portion and provides a corresponding plurality of fluid flow passages between the first protrusion portion and the second base portion; The two protruding portions are spaced relative to the first base portion to provide a corresponding plurality of fluid flow passages between the second protruding portion and the first base portion. The filter according to 1. The at least one spacer portion is provided between the first layer of sheet material and the second layer of sheet material to control the distance between the first layer and the second layer. Filter. 6. The plurality of spacer portions between the first layer of sheet material and the second layer of sheet material are provided to control the distance between the first layer and the second layer. filter. 6. The filter of claim 5, wherein at least one spacer portion is made in one of the first layer and the second layer. At least a portion of the plurality of protrusions extending from the other one of the first layer and the second layer further comprising a layer of filter material applied to at least one base portion of the first layer and the second layer 5. The filter of claim 4, wherein the filter is in contact with the layer of filter material and provides a corresponding plurality of fluid flow passages within the filter material. A gas generation system comprising the filter according to claim 1. The gas generation system of claim 9, wherein at least a portion of the plurality of first openings through the first layer is in fluid communication with a combustion chamber of the gas generation system. A vehicle occupant protection system comprising a gas generation system comprising the filter of claim 1.

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