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`US005618057A
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`United States Patent
`
`[191
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`[11] Patent Number:
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`5,618,057
`
`Johnson et al.
`
`[45] Date of Patent:
`
`Apr. 8, 1997
`
`[54]
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`[75]
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`[73]
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`[21]
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`[22]
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`[51]
`[52]
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`[58]
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`[56]
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`CONTINUOUSLY VARIABLE CONTROLLED
`ORIFICE INFLATOR
`
`Inventors: Kelly B. Johnson, Layton; Brett
`Hussey, Bountiful, both of Utah
`
`Assignee: Morton International, Iuc., Chicago,
`Ill.
`
`Appl. No.: 529,181
`
`Filed:
`
`Sep. 15, 1995
`
`Int. Cl.“ ................................................... .. B60R 21/26
`U.S. Cl. ............................ 280/736; 280/742; 137/71;
`137/543.15; 222/3
`Field of Search ................................... .. 280/736, 737,
`280/740, 741, 742; 137/71, 543.15; 222/3
`
`References Cited
`
`U.S. PATENT DOCUMENTS
`
`533,806
`3,638,964
`
`..
`2/1895 Hesketh et al.
`2/1972 Chute ................
`
`137/71
`280/736
`
`5/1977 Suzuki etal. ........................... 280/737
`4,021,058
`4,172,465 10/1979 Dashner .... ..
`137/543.15
`
`..... .. 280/736
`5,195,777
`3/1992 Cuevas
`11/1993 Cuevas .................................. .. 280/736
`5,257,817
`
`Primary Examiner—B1ian L. Johnson
`Assistant Examiner—Peter C. English
`Attorney, Agent, or Firm—Char1es N. Lovell; Gerald K.
`White
`
`[57]
`
`ABSTRACT
`
`An air bag inflation which includes a gas source and a gas
`outlet opening for allowing flow of gas from the gas source
`into the air bag wherein the flow of gas is controlled with a
`valve assembly including a piston disposed in a cylinder and
`features a piston against which the gas acts to cause move-
`ment of the piston in a first direction in the cylinder to
`provide an increased flow of gas through the gas outlet
`opening and further includes a spring disposed in the path of
`movement of the piston so that as the piston moves in the
`cylinder the spring provides resistance to the movement of
`the piston.
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`5 Claims, 2 Drawing Sheets
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`U.S. Patent
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`Apr. 8, 1997
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`Sheet 1 of 2
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`5,618,057
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`U.S. Patent
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`Apr. 8, 1997
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`Sheet 2 of 2
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`5,618,057
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`5,618,057
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`1
`CONTINUOUSLY VARIABLE CONTROLLED
`ORIFICE INFLATOR
`
`CROSS~REFERENCE
`
`This application is related to application Ser. No. 08/528,
`972 filed on even date herewith, entitled A“Pintle Controlled
`Orifice Inflator” (Morton Docket 2530-21-00) by the same
`inventors herein.
`
`BACKGROUND OF THE INVENTION
`
`1. Technical Field
`
`The present invention relates to a hybrid air bag inflator,
`and more particularly to apparatus for controlling the rate of
`gas flow from a hybrid air bag inflator.
`2. Description of the Prior Art
`Air bag inflatable restraint systems commonly include an
`air bag and an inflator for providing gas to inflate the air bag.
`In hybrid air bag or augmented stored gas inflator systems a
`quantity of gas is stored under pressure in the inflator. Upon
`actuation of the inflator, the gas is released and directed into
`the air bag to effect its inflation. In vehicle restraint systems
`including an air bag, it is desirable to control the operating
`pressure hi the air bag to ensure the desired amount of
`inflation at the desired time. Controlling the rate of flow of
`gas into the air bag controls bag inflation. Valving is
`typically used for controlling gas flow from the inflator. U.S.
`Pat. No. 3,638,964 discloses a moveable member for con-
`trolling the release of gas into an air bag. A quantity of
`silicone oil or grease is forced through an outlet to retard and
`thereby control movement of the moveable member. U.S.
`Pat. No. 5,195,777 discloses a valve assembly for control-
`ling the flow of gas out of an inflator. The valve assembly
`includes a piston slidably received in a cylinder and a
`crushable honeycomb disposed in the path of movement of
`said piston for controlling movement of said piston in said
`cylinder.
`
`SUMMARY OF THE INVENTION
`
`The present invention is directed to an apparatus for
`inflating vehicle air bag restraint systems. The apparatus
`comprises a gas generator including a diflhser region and
`means for defining controlled (choked) gas outlet opening
`orifices in said diffuser region where the gas is turned and
`exits the generator to inflate the air bag. The means defining
`said gas outlet orifices includes a piston located in the
`diffuser region where the gas exits the generator. The piston
`is spring loaded with any spring-like material which allows
`motion of the spring relative to the difiuser. As the piston
`moves under pressure, from the generated gases it slides past
`the controlling orifices opening up the flow area,
`thus
`changing the cross-sectional flow area of the orifices over a
`continuously variable range. The operational pressure and
`mass flow rate from the generator is directly dependent on
`the flow area of the controlling orifices. When the gas
`generator encounters higher operating temperatures,
`the
`burning rate and pressure tend to increase. The piston
`controlled orifices will reduce such pressure increases by
`opening up the controlling orifices,
`thus equalizing the
`performance of the gas generators as a function of tempera-
`ture. Similar behavior occurs during cold operation when
`pressures and burn rates are lower. Under these conditions,
`less flow area is opened up, and thus more pressure is created
`by the combustion of the pyrotechnic. The inflator therefore
`acts more like an ambient shot than a cold shot. The spring
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`can initially be placed under load, ie. biased to provide more
`of a delay, for the obtention of certain tuning parameters.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`The foregoing and other features of the present invention
`will become apparent
`to one skilled in the art upon a
`consideration of the following detailed description of the
`invention with reference to the accompanying drawings.
`FIG. 1 is a longitudinal sectional view of an inflator
`embodying the present invention.
`FIG. 2 is an enlarged view of a portion of FIG. 1 showing
`a valve assembly in closed position; and
`FIG. 3 is an enlarged view of a portion of FIG. 1 showing
`a valve assembly in open position.
`
`DESCRIPTION OF PREFERRED EMBODIMENT
`
`The present invention relates to an air bag inflator and
`particularly to an inflator for inflating an air bag to protect
`the passenger of a vehicle. The present invention is appli-
`cable to various inflator constructions. As representative of
`the present invention, FIG. 1 illustrates an inflator 10 for
`inflating an air bag (not shown) to protect passengers of a
`vehicle. The inflator 10 is an augmented inflator having a
`quantity of gas stored in a container in the inflator, usually
`under pressure. The inflator includes an initiator and a
`quantity of combustible material disposed in the container.
`Upon actuation of the inflator,
`the initiator ignites the
`combustible material, which generates heat to raise the
`pressure of the gas stored in the container. The combustible
`material also generates additional gas to augment the gas
`stored in the container. The stored gas and the gas generated
`by the combustible material are directed into the air bag to
`cause it to inflate. It should be understood that the present
`invention could be embodied in an inflator which uses only
`combustible material
`to generate gas, rather than in an
`augmented inflator.
`The inflator 10 includes a quantity of gas stored under
`pressure in container 12. The gas is preferably argon,
`although other gases such as nitrogen or air could be used.
`The container 12 includes a housing 14 and a diffuser 16,
`which is attached to housing 14 by attachment boss 18. The
`difl°user 16, attachment boss 18 and housing 14 are welded
`together. An initiator assembly 20, which includes an ini-
`tiator and a quantity of combustible gas generating material
`is disposed within container 12 adjacent one of its ends. A
`burst disk 22 seals an opening 24 in the attachment boss 18.
`Diffuser 16 is cup-shaped with radial holes (controlling
`orifices) 40 to direct gases from the inflator into the air bag.
`The inflator 10 includes a valve assembly 30 for control-
`ling the flow of gas out of the inflator. The valve assembly
`30 includes a cylinder 32 formed as part of the diffuser 16.
`The cylinder extends axially outward from a radially extend-
`ing portion 34 of attachment boss 18. The cylinder 32 has a
`cylindrical outer surface 36 and a cylindrical inner surface
`38 between which extend a plurality of radial gas outlet
`openings 40.
`A piston guide 50 is secured in the cylinder 32. The piston
`guide 50 has a radially extending base portion 52 and a guide
`pin 54 projecting axially from the base portion. The guide
`pin 54 has a cylindrical outer surface 56 extending parallel
`to the inner surface 38 of cylinder 32.
`A piston 60 is disposed in the cylinder 32. The piston 60
`has a radially extending surface 62 facing axially inward
`toward the burst disk 22. The piston 60 also has a radially
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`extending surface 64 facing axially outward toward the
`piston guide base 52. The piston 60 has a cylindrical outer
`surface 66 in sliding engagement with the inner surface 38
`of the cylinder 32, and a cylindrical inner surface 68 defining
`a central opening through which the guide pin 54 extends.
`A coil spring 70 is disposed in cylinder 32. The material
`used for making the spring is not critical. Any material
`typically used for springs and which allows motion of the
`spring and piston relative to the diffuser can be employed in
`making the spring 70, eg. spring steel, brass, etc.. Coil spring
`70 can be cylindrical or conical in shape and can be made
`with a circular or rectangular cross section.
`The axially inner end 72 of the springis in abutting
`relation with surface 64 of piston 60. The axially outer end
`74 of spring 70 is in abutting engagement with the piston
`guide base 52. In a typical installation, the guide pin 54,
`spring 70 and piston 60 are placed into the diffuser 16. The
`diifuser 16 is then placed onto shoulder 26 of attachment
`boss 18 and the dilfuser is welded to the attachment boss 18
`by any conventional welding process. The attachment boss
`18 is initially welded onto housing 14, as shown in FIG. 1.
`A small amount of spring preload is desirable to prevent the
`rattle of loose parts. The amount of preloading can be
`advantageously used as a tuning parameter that allows
`tailoring of the inflator performance to meet the specific
`needs of each design application.
`FIG. 2 illustrates the parts of the valve assembly 30 in a
`first condition prior to activation of the inflator 10. The burst
`disk 22 is intact, maintaining the gas in the container. The
`piston 60 is disposed at the axially inner end of the cylinder
`32 between the opening 24 and the gas outlet openings 40.
`The spring 70 is disposed between the piston 60 and the
`piston guide base 52.
`Upon actuation of the inflator 10, the initiator assembly
`heats the gas in the container 12 to raise its pressure. The
`initiator assembly 20 also generates additional gas to aug-
`ment the gas stored in the container 12. When the gas
`pressure in the container 12 reaches a predetermined level,
`the burst disk 22 bursts, as shown in FIG. 3. The gas contacts
`the surface 62 of piston 60, causing the piston to move in a
`first direction in the cylinder 32, from the position shown in
`FIG. 2 to the position shown in FIG. 3.
`The spring 70 is disposed in the path of movement of the
`piston 60 with the coils of the spring oriented transversely to
`the path of movement. The spring 70 resists and slows
`movement of the piston 60 but does not block such move-
`ment. The force exerted by the moving piston 60 on the
`spring 70 causes the spring to be compressed between the
`moving piston and the piston guide base 52. The spring 70
`compresses from its axially inner surface 72 to its axially
`outer surface 74. When the piston 60 has completed its path
`of movement in the cylinder 32, the spring 70 is compressed,
`as is seen in FIG. 3.
`
`As the piston 60 moves in the cylinder 32, it exposes the
`gas outlet openings 40. The gas from the container 12 flows
`through the opening 24 and through the gas outlet openings
`40. The gas then flows into the air bag (not shown) to cause
`its inflation.
`
`As the piston 60 moves in the cylinder 32, the piston
`exposes an increasing amount of gas exhaust area through
`the gas outlet openings 40. The speed of movement of the
`piston 60 is controlled by the spring 70. As the piston 60
`travels down the cylinder 32 the spring provides resistance
`to the movement of the piston. The construction of spring 70
`can be varied to control the compression rate of the spring
`and thus the rate of movement of the piston 60 in the
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`cylinder 32. Thus, by selecting an appropriate spring, it is
`possible to control the rate of the gas flow from the inflator
`10 into the air bag.
`The spring acts in a linear fashion to influence the burning
`behavior through the entire combustion process. Early on,
`the spring will resist piston movement,‘ however, when the
`pressure begins to decline, the piston will move back over
`the diffuser orifices, slowing the mass flow out of the
`inflator. This will result in a higher inflator pressure than
`would be provided with a constant controlling orifice area
`and therefore faster combustion. This will provide a sus-
`tained period at relatively constant pressure, better perfor-
`mance after peak pressure is reached, and a quicker tailoff of
`the inflator pressure. In addition, the device may allow use
`of a simpler pyrotechnic shape to achieve neutral-burn
`characteristics. In brief, the spring loaded device of the
`present invention advantageously influences performance
`throughout the entire combustion event in contrast to prior
`art devices, such as the device of U.S. Pat. No. 5,195,777
`which influences performance only up to the time of peak
`inflator pressure.
`From the above description of the invention, those skilled
`in the art will perceive improvements, changes and modi-
`fications in the invention. Such improvements changes and
`modifications within the skill of the art are intended to be
`covered by the appended claims.
`What is claimed is:
`
`~1. An inflator for providing gas to inflate an air bag
`comprising:
`a gas source stored under pressure in a container, said
`container having a gas outlet end,
`said container including a diffuser shaped in the form of
`a cylinder aifixed to said gas outlet end of said con-
`tainer,
`
`means for defining a gas outlet opening in said diifuser to
`allow flow of gas from said gas source into said air bag
`to cause said air bag to inflate, and
`valve means for controlling flow of said gas through said
`diifuser gas outlet opening,
`said valve means comprising a spring loaded piston
`slidably contained within said cylinder,
`said piston having a first radially extending surface
`against which said flow of gas moves said piston in a
`first direction to allow increased flow of gas through
`said gas outlet opening,
`said valve means including a coil spring disposed in the
`path of movement of said piston for controlling the
`movement of said piston in said cylinder.
`2. Apparatus as claimed in claim 1 wherein said diffuser
`chamber comprises a longitudinally extending wall defining
`the path of movement of said piston, said diffuser having an
`axially inner cylinder portion in which said gas outlet
`opening is formed, said piston being disposed in a first
`position in said inner cylinder portion prior to actuation of
`said apparatus, said cylinder including an axially outer
`portion in which said coil spring is disposed, said gas acting
`to move said piston in said first direction from a first position
`to a second position at least partially in said axially outer
`portion of said cylinder against the resistance of said coil
`spring.
`3. Apparatus as defined in claim 2 wherein said piston is
`in the shape of an armulus, having a central axially extending
`opening, said coil spring having an axially extending central
`opening, said diffuser having a guide pin fixed to a piston
`guide base located in an end of said difl°user, said pin
`extending through said central opening in said piston and
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`said coil spring to guide movement of said piston in said
`diffuser.
`4. Apparatus as defined in claim 3 wherein said coil spring
`comprises a plurality of coils extending transverse to said
`first direction including an axially inner coil in abutting 5
`relationship with the piston and an axially outer coil in
`abutting relationship with the piston guide base, movement
`
`of said piston in said first direction acting to compress said
`C0flS_
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`5. Apparatus as defined in claim 3 wherein said coil spring
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`UNITED STATES PATENT AND TRADEMARK OFFICE
`
`CERTIFICATE OF CORRECTION
`
`PATENT NO.
`
`; 5. 618 . 057
`
`DATED
`
`2 8 April 1997
`
`WVEN“WS)i Kelly B. Johnson and Brett Hussey
`
`It is certified that error appears in the above-indentified patent and that said Letters Patent is hereby
`corrected as shown below:
`
`At title page, Abstract,
`
`line 1, "inflation" should be
`——inflator--.
`-
`
`At column 4,
`
`lines 50 and 51, "diffuser chamber comprises"
`should be
`
`-—diffuser comprises--.
`
`Signed and Sealed this
`
`Thirtieth Day of September, 1997
`
`Am
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`@4144 7:;/Cr>~.u.\
`
`BRUCE LEHMAN
`
`Arteszing 0_ffIC€I‘
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`CrnmJIi.s.\‘I'rHIm‘ of Ptlrmm. and Tl'lH](’IHLl7‘k.\'
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