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`
`PATENT DATE
`· -JUN 3 O 1998
`
`PATENT
`NUMBER
`
`FILING DATE CLASS
`1 :2: / :t ::~: / '31 !.:1
`:;;:~ :::: 0
`
`SUBCLASS
`
`GROUP ART UNIT
`J106
`
`BREEI>,. BOONTON TOWNSHI. NJ; W. THOMAS SANDERS, ROCKAWAY ~OWNSH,
`
`·,:
`
`#,#A'L--
`**CONTINUING DATA*********************
`VEF<IFIED
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`* * FOF-:E I GN /PCT APPL I ChT I ON!:':;*****~~:*
`VERIFIEiI:i
`,j
`
`FOREIGN FILING LICENSE GRANTED 02/27/96
`
`***** SMALL ENTITY*****
`
`Foreign priority claimed
`35 use 119 conditions met
`Verified and Acknowledged
`Dl:;:IP,N F<OF E
`:J76 Y1:\LE AVENUE
`WOODMERE NY
`11698-2051
`
`D yes
`no
`D ye~e::
`Exa~ner's initials
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`STATE OR SHEETS
`AS
`FILED COUNTRY DRWGS.
`-+ N.J
`· 17
`
`TOTAL
`CLAIMS
`20
`
`INDEP.
`FILING FEE
`ATTORNEY'S
`CLAIMS RECEIVED
`DOCKET NO.
`.-•,
`!f;:::i75. 00 ?'~TI -··6!.:;
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`..... 'i
`
`EFFICIENT AIRBAG MODULE
`
`U.S. DEPT. OF COMM./ PAT. & TM-PT0-436L (Rev.12-94)
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`PARTS OF APPLICATION
`FILED SEPARATELY
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`NOTICE OF ALLOWANCE MAILED
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`Form PT0-436A
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`WARNING: The information disclose
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`,/
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`Date
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`Counted
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`i
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`l.
`
`-S APPR~VED FOR LICENSE. D .
`PATENT APPLICATION
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`• -C,0i'41 I Ll,iT-"-' ____________ _
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`Date
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`Mailed
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`
`___ __ 1. Application
`
`- \"·~
`- - - - - 2. -
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`- - - - - 3. ~~~--.....;-----'--'---=-=-----
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`_____ 15. - - - - - - - - - - - (cid:173)
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`_____ 22. --------------e:---(cid:173)
`___ __ 23. - - - - - - - - - - - " - - (cid:173)
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`------,---24. - - - - - - - - - - - (cid:173)
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`_ ___ _ 25. - - - - - - - - - - - -
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`
`_____ 31. - - - - - - - - - - - (cid:173)
`
`_ __ __ 32. - - - - " - - - - - - " - - - -
`(FRONT)
`
`2
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`U.S. DEPARTMENT OF COMMERCE
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`52
`53
`54
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`57
`58
`59
`60
`61
`62
`63
`64
`65
`66
`67
`68
`69
`70
`71
`72
`73
`74
`75
`76
`77
`78
`79
`80
`81
`82
`83
`84
`85
`86
`87
`88
`89
`90
`91
`92
`93
`94
`95
`96
`97
`98
`99
`100
`
`SYMBOLS
`
`Rejected
`../ ......
`........... Allowed
`=
`• (Through numberal) Canceled
`+ ................................. Restricted
`N ................................. Non-elected
`I ............................... Interference
`A ................................ Appeal
`0 ................................. Objected
`
`(LEFT INSIDE)
`1
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`39
`40
`41
`42
`43
`44
`45
`46
`47
`48
`49
`50
`
`INDEX OF CLAIMS
`
`Date
`
`SYMBOLS
`./ ................................. Rejected
`= ................................. Allowed
`• (Through numberal) Canceled
`+ ................................. Restricted
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`51
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`58
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`91
`92
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`Date
`
`.
`
`I
`
`5
`
`

`

`..
`
`PATENT APPLICATION SERIAL NO.
`
`U.S. DEPARTMENT OF COMMERCE
`PATENT AND TRADEMARK OFFICE
`FEE RECORD SHEET
`
`PT0-1556
`(5/87)
`
`1
`
`6
`
`

`

`BAR CODE LABEL
`
`llllllllllllllllllllllllllllllllllllllllllllllllll
`
`U.S. PATENT APPLICATION
`
`SERIAL NUMBER
`
`FILING DATE
`
`CLASS
`
`GROUP ART UNIT
`
`08/571,24 7
`
`12/12/95
`
`280
`
`3106
`
`~ DAVID S. BREED, BOONTON TOWNSHI, NJ; W. THOMAS SANDERS, ROCKAWAY TOWNSH,
`z
`~ NJ.
`:::;
`~
`
`**CONTINUING DATA*********************
`VERIFIED
`
`**FOREIGN/PCT APPLICATIONS************
`VERIFIED
`
`FOREIGN FILING LICENSE GRANTED 02/27/96
`
`***** SMALL ENTITY *****
`
`STATE OR
`COUNTRY
`
`SHEETS
`DRAWING
`
`TOTAL
`CLAIMS
`
`INDEPENDENT
`CLAIMS
`
`FILING FEE
`RECEIVED
`
`ATIORNEY DOCKET NO.
`
`NJ
`
`17
`
`20
`
`3
`
`$375.00
`
`ATI-65
`
`BRIAN ROFFE
`376 YALE AVENUE
`WOODMERE NY
`11598-2051
`
`~
`LU cr:
`0
`0
`<1:
`
`EFFICIENT AIRBAG MODULE
`
`This is to certify that annexed hereto is a true copy from the records of the United States
`Patent and Trademark Office of the application wh1ch is identified above.
`
`By authority of the
`COMMISSIONER OF PATENTS AND TRADEMARKS
`
`Date
`
`Certifying Officer
`
`1
`
`7
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`

`

`PATENT APPLICATION TRANSMITTAL LETTER
`
`08/571247
`
`__ Jacket Number'(Optional)
`ATI-65
`
`the Commissioner of Patents and Trademarks:
`·
`herewith for
`·
`under 35 U.S.C: 111 and 37 CFR 1.53 is the patent application of
`
`osed are:
`pages ofwritt~n description; claims and abstract.;/'1:? pc:Je,qppet·ltt-'ly
`49
`[XI
`00
`sheets of drawmgs.
`'
`17
`an assignment of the invention to Automotive Technologies Intl., Inc.
`[X] l (copy)
`[XI executed declaration of the inventors. (1 pages)
`[XI PT0-1595 for assignment.
`D associate power of attorney.
`[XI a verified statement to establish small entity status under 3 7 CFR 1. 9 and 1.2 7 (2 pages)
`[]g. Information disclosure statement, PT0-1449, 26 references
`D preliminary amendment
`D other:~~~~~~~~~~~~~~
`
`CLAIMS AS FILED
`
`BASIC FEE
`TOTAL CLAIMS
`INDEPENDENT CLAIMS
`MULTIPLE DEPENDENT CLAIM PRESENT
`
`FEE
`$750
`$
`$78 $
`$250
`
`*NUMBER EXTRA MUST BE ZERO OR LARGER
`
`TOTAL
`
`$750
`
`If applicant has small entity status under 37 CFR 1.9
`and 1.27, then divide total fee by 2, and enter amount here
`
`SMALL ENTITY
`TOTAL
`
`$375
`
`415 _ 00
`
`to cover the filing fee and assignment
`
`lXI Check totaling the amount of$
`recording fee is enclosed_
`D The Commissioner is hereby authorized to charge and credit Deposit Account
`as described below. I have enclosed a duplicate copy of this sheet.
`No.
`D Charge the amount of$
`as filing fee.
`D Charge any additional filing fees required under 3 7 CFR 1.16 and 1.17.
`D Charge the issue fee set in 37 CFR 1.18 at th~iling ofthe N22ti of
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`.· -·
`____ _
`7
`-:e'~t ~
`December Hl. 1995
`Date
`'
`
`·
`Signature
`Brian Roffe
`376 Yale Avenue
`Woodmere New York 11598
`
`Express Mail Mailing Label No. EG 390 267 475 US
`Date ofDeposit: December Q., 1995
`I hereby certify that this correspondence and/or fee is being deposited with the United States Postal
`Service "Express Mail Post Office to Addresse" service under 37 CFR 1.10 on the date indicated
`·
`ofPatents and Trademarks, Washington, D.C
`above, in an envelope
`dressed to
`20231" Brian''""'-"'/
`
`1/6
`
`(2-92)
`
`Patent and Trademark Office: U.S. DEPARTMENT OF
`COMMERCE
`
`1
`
`8
`
`

`

`AN~FF:CIE~JT AIRBAG MODULE
`
`. ·~
`
`NCE TO RELATED APPLICATIO
`
`!}/
`08. 15?124'7
`5-:J~--~"
`~~-~.
`
`pplicatibns (A Tl-64) "Airbag System" --------filed
`
`October 30, 1995, U.S. patent application Serial o. 08/247,763 entitled "Film Airbags" filed May 23,
`
`1994 and U.S. patent application Serial No. 08~ 39,676 entitled "Airbag System With Self Shaping
`
`Airbag", filed October 5, 1995, all of which are i corporated by reference herein.
`
`FIELD OF THE INVENTION
`
`j0
`
`This invention is in the field of inflator evices for inflating airbag occupant restraints mainly for
`
`the protection of occupants of automobiles a d trucks although it also is applicable to the protection of
`
`occupants of other vehicles and for inflati g other inflatable objects.
`
`In particular, by means of the
`
`present invention, a more efficient utilizaf n of the energy in a propellant is attained resulting in the
`
`need for a lower amount of propellant th n in currently existing inflators, and t~1us a smaller inflator, to
`
`15
`
`inflate a given size inflatable object. Th s is accomplished in part through a more efficient aspirating
`
`nozzle design and an improved geomet of a gas generator which houses the propellant.
`
`BACKGROUND OF THE INVENTION
`
`Most airbag modules in use t ay are large, heavy, expensive, and inefficient. As a result, airbags
`
`20
`
`are now primarily only used for pro ecting the passenger and driver in a frontal impact, although at least
`
`three automobile manufacturers c rrently offer a small airbag providing limited
`
`25
`
`Express Mail Mailing Label No. EG 90 267 475 US
`Date of Deposit December 1a, 1995
`I hereby certify that this corresponde ce and/or fee is being deposited with the United States Postai Service "Express
`Mail Post Office to Addressee" service under 37 CFR 1.10 on the date indicated above, in an envc;ope addressed to
`the "Commissioner of Patents and Trademarks, Washington, D.C. 20231"
`
`ATI-65F .DOC
`
`1
`
`1
`
`9
`
`

`

`protectio..Q_in side impacts. ·
`
`; main advantage of airbags over oth
`
`that they utilize the space between the occupant and vehicle interior surfaces to a sorb the kinetic
`
`11e.r.g_~ng structures is
`
`energy of the occupant during a crash, cushioning the impending >impact of the occupant with the
`
`vehicle interior surfaces. Airbags have been so successful in frontal impacts th
`
`it is only a matter of
`
`5
`
`time before they are effectively used for side impact protection, protection for ear seat occupants and
`
`in place of current knee bolsters. Substantial improvements,
`
`ust be made in airbags
`
`before they assume many of these additional tasks
`
`A good place to start describing the problems with current air ags is with a calculation of the
`
`amount of energy used in a typical airbag inflator and how muc energy is required to inflate an
`
`10
`
`airbag. By one analysis,
`
`the chemical propellant in a ty ical driver's side
`
`inflator contains
`
`approximately 50,000 foot pounds (68,000 joules) of energy A calculation made to determine the
`
`energy required to inflate a driver's side airbag yields an estimate of about 500 foot pounds (680
`
`joules). A comparison of these numbers shows that ap roximately 99% of the energy in a chemical
`
`propellant is lost, that is, generated but not needed f
`
`inflation of the airbag. One reason for this is
`
`15
`
`that there is a mismatch between the output of a b rning propellant and the inflation requirements of
`
`an airbc.1g.
`
`In engineering this is known as a
`
`impedance mismatch. Stated simply, propellants
`
`naturally produce gases having high temper, tures and high pressures and low gas flow rates.
`
`Airbags, on the other hand, need gases wit
`
`low temperatures and low pressures and high gas flow
`
`rates.
`
`20
`
`In view of this impedance mis
`
`tch, inflators are, in theory at least, many times larger then
`
`they would have to be if the energ of the propellant contained within the inflator were efficiently
`
`utilized. Some attempts to partial
`
`solve this problem have resulted in a so called "hybrid" inflator
`
`where a stored pressurized gas 1s heated by a propellant to inflate the airbag. Such systems are
`
`considerably more energy effi ent, however, they also require a container of high p:··:;ssure gas and
`
`25 means for monitoring the pre sure in that container. Other systems have (, .. empted to use aspiration
`
`ATI-65F.DOC
`
`2
`
`1
`
`10
`
`

`

`techniques, but because o,
`
`a geometry constraints of current ~c..
`I
`locations, and for other reasons, currently used aspiration systems are only able to draw up to about
`
`flator designs and mounting
`
`30% of the gas needed to inflate an airbag from the passeng
`
`compartment. Theoretical studies
`
`have shown that as much as 90% or more of the gas could be o tained in this manner.
`
`5
`
`Furthermore, since inflators are large and inefficient, s vere restrictions have been placed on
`
`the type of propellants that can be used since the combu
`
`ion products of the propellant must be
`
`breathable by automobile occupants.
`
`It is of little value to save an occupant from death in an
`
`automobile accident only to suffocate him from an excessi e amount of carbon dioxide in the air within
`
`the passenger compartment after the accident.
`
`If inflat rs operated more efficiently, then alternate,
`
`10 more efficient but slightly toxic propellants could be
`
`current inflators are made from
`
`propellants, namely sodium azide, which are not total consumed. Only about 40% of the mass of
`
`sodium azide propellants currently being used, for e ample, enters the airbag as gas. This residual
`
`mass is very hot and requires the inflator to be
`
`ounted away from combustible materials further
`
`adding to the mass and size of the airbag system.
`
`15
`
`It is a persistent problem in the art that ma y people are being seriously injured or even killed
`
`today t·y the airbag itself. This generally happen when an occupant is out-of-position and against an
`
`airbag module when the airbag deploys.
`
`In or,er to open the module cover, sometimes called the
`
`deployment door, substantial pressure must /irst build up in the airbag before enough force is
`
`generated to burst open the cover. This press?re is even greater if the occupant is in a position which
`
`20
`
`prevents the door from opening. As a result/worK is underway to substantially reduce the amount of
`
`energy required to open the deployment doors and devices have been developed which pop off the
`/
`deployment door or else cut the deployment door material using pyrotechnics, for example.
`
`One reason that this is such a significant problem is that the airba9 nodule itself is quite large
`/
`and, in particular, the airbags are made fut of thick, heavy material and f)ackaged in a poor, folded
`
`25
`
`geometry. The airbag, for example, w ich protects the passenger is housed in a module which is
`
`ATI-65F.DOC
`
`3
`
`1
`
`11
`
`

`

`typically about one th_ird ·a~
`
`g as the deployed airbag. All of thl
`
`)avy airbag material must be
`
`rolled and folded inside this comparatively small module, thus requinn~ su~antial energy to unfold
`
`during deployment. This situation could be substantially improved if the a/bag module were to have
`
`an alternate geometry and if the airbag material were substantially light~and thinner and, therefore,
`less massive and folded mainly parallel to the inflator. Even the ~ime to deploy the airbag is
`
`5
`
`substantially affected by the mass of the airbag material and the ?~ed to unfold an airbag with a
`
`complicated folding pattern. Parallel folding, as used herein, meanj that the airbag material is ·folded
`with the fold lines substantially parallel the axis of the inflator wit~~ut being folded over lengthwise as
`
`is now done with conventional airbag folding patterns.
`/
`Devices are under development which will monitor the r~sition of the occupant and prevent the
`
`10
`
`airbag from deploying if the occupant is dangerously close ;to the module where he or she can be
`
`seriously injured by the deployment. Some systems w1 also prevent deployment if the seat in
`
`connection with which the airbag operates is unoccupie1d. An alternate approach is to move the
`I
`deployment doors to a location away from normal occupint positions. One such location is the ceiling
`
`15
`
`of the vehicle. One problem with ceiling mounted airb9'gs is that the distance required for the airbag
`
`I
`
`to travE.d, in some cases, is longer and therefore a Ia ger airbag is needed with greater deployment
`
`time. With the use of light airbag materials, such as thin plastic film, as disclosed in the above
`
`referenced patent applications Serial Nos. 08/247'163 and 08/539,676, and the use of more efficient
`
`inflators, both of these problems can be solved es , ecially for the front and rear seat passengers. The
`
`20
`
`driver poses a different problem since it would b difficult to position a ceiling mounted airbag module
`
`where the airbag would always be projected pro erly between the occupant and the steering wheel.
`I
`This problem for the driver's airbag sttem is not the concept of mounting the airbag on the
`
`ceiling, but the design of the steering wheel '·nd steering column. The.se d~signs come from t.he. time
`
`when the only way of steering an automof11e was through mechamcal linkages. The majonty of
`
`25
`
`vehicles manufactured today have power I ssisted steering systems and, in fact, most drivers would
`
`ATI-65F.DOC
`
`4
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`1
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`12
`
`

`

`have difficulty steering a cc.
`
`jay if the power steering failed. If se.
`
`)OJer steering were used, the
`
`need for a mechanical linkage between a steering wheel, or other such device, and the power
`I
`steering system would no longer be necessary. Servo power steering foj the purposes here will mean
`those cases where the linkage between the manually operated stee~~g device, which regardless of
`
`5
`
`what that device is, will herein be called a steering wheel, is d1ne with a servo system either
`
`electrically or hydraulically and the system does not have an fperative mechanical connection
`
`10
`
`15
`
`between the steering wheel and the steering mechanism which mq~es the wheels.
`I I
`The problem of educating the general population, which ~as become secure in the feeling of a
`I
`I
`steering wheel and steering column, might be insurmountable d it were not for the substantial safety
`!
`!
`advantage resulting from substituting servo power steering for conventional steering systems and
`/
`using a non-steering wheel mounted airbag module for the dr)'ver.
`I
`l
`The steering wheel and steering column are among the most dangerous parts of the vehicle to
`
`I
`
`I
`I
`/
`the occupant. Small people, for example, who are wearifl'g seatbelts can still be seriously injured or
`I /
`killed in accidents as their faces slam into the steerirjg wheel hubs. The problem of properly
`! I
`positioning an airbag, when the comfort and convenienc;e features of telescoping and tilting steering
`
`/'
`I
`/
`columr1s are considered, results in substantial safety/ compromises. Deployment induced injuries
`I
`which result when a small person is close to the steeriQg wheel when the airbag deploys have already
`I
`caused several deaths and numerous serious injurie$. Future vehicles, therefore, for safety reasons
`I I
`should be constructed without the massive steering v(heel and steering column and substitute therefor
`
`I
`
`20
`
`a servo steering assembly. With this modificatfn. a ceiling mounted airbag. module, such as
`
`discussed herein, becomes feasible for the dnver 7 well as the other seatmg pos1t1ons m the veh1~le.
`
`The front seat of the vehicle today has an 1rbag for the passenger and another for the dnver.
`
`In some accidents, an occupant, and particularly
`
`center seated occupant, can pass between tt1e two
`
`A TI-65F. DOC
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`5
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`1
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`13
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`

`

`used, a single airbag cou.
`
`3 deployed to cover the entire front , . .,atly simplifying the airbag
`
`system design.
`
`I
`
`One method of partially solving many of these problems is t use an efficient aspirated airbag
`
`system. There have been numerous patents granted on design
`
`for airbag systems using aspirated
`
`5
`
`inflators.
`
`In these patents as well as in the discussion herein t e term. "pumping ratio" is used. The
`
`pumping ratio as used in the art is defined as the ratio ~· the mass of gas aspirated from the
`
`environment, either from inside or outside of the vehicle, to the mass of gas generated by burning the
`
`propellant. A brief description of several pertinent pa ents, all of which are included herein by
`
`reference, follows:
`
`10
`
`U.S. Patent No. 2,052,869 to Coanda illustra s the manner in which a fluid jet is caused to
`
`change direction, although no mention is made of its use in airbags. This principle, the "Coanda
`
`effect", is used in some implementations of th
`
`instant invention as well as in U.S. Patent No.
`
`3,909,037 to Stewart discussed below. It's prim,ry contribution is that when used in inflator designs, it
`permits a reduction in the length of the nozz'irequired to efficiently aspirate a~r into the airbag. No
`
`15
`
`disclosure is made of a pumping ratio in lh's system and in fact it is not an object of Coanda to
`
`aspirate fluid.
`
`U.S. Patent No. 3,204,862 to Hadf'er also predates the invention of vehicular airbags but is
`
`nonetheless a good example of the use(! aspiration to inflate an inflatable structure.
`
`In this device,
`
`an inflating gas is injected into an ann lar converging-diverging nozzle and some space efficiency is
`
`20
`
`obtained by locating the nozzle so th t the flow is parallel to the wall of the inflatable structure. No
`
`mention is made of a pumping ratio
`
`f this device and furthermore, this device is circular.
`
`U.S. Patent No. 3,632,133 ·o Hass provides a good example of a nozzle in a circular module
`
`with a high pumping ratio in an early construction of an airbag. Although analysis indicates that
`
`pumping ratios of 4:1 or 5:1
`
`7uld be difficult to achieve with this des1gn as illustrated, nevertheless,
`
`q
`
`ATI-65F.DOC
`
`6
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`1
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`14
`
`

`

`this re~nce illustra.tes t~t
`
`Le and rough shape of an aspirating .
`
`,em which is required to obtain
`
`high pumping ratios using the prior art designs.
`
`)
`
`U.S. Patent No. 3,909,037 to Stewart provides a good example of the ap 1cation of the
`
`Coanda effect to airbag aspirating inflators. Stewart, nevertheless, still discards mo t of the energy in
`
`5
`
`the propellant which is absorbed as heat in the inflator mechanism. Most prop
`
`!ants considered for
`
`airbag applications burn at pressures in excess of about 1000 psi g. St art discloses that the
`
`maximum efficiency corresponding to a 5:1 pumping ratio occurs at infll gas pressures of about 5
`
`In order to reduce the pressure, Stewart utilizes J complicated filtering system
`
`to about 45 ps1g.
`
`similar to that used in conventional inflators. Stewart requires th/ use of valves to close off the
`
`10
`
`aspiration ports when the system is not aspirating. Through the ;Jse of the Coanda effect, Stewart
`
`alludes to a substantial reduction in the size of the aspiration sylem, compared to Hass for example.
`
`Also, Stewart shows only a simple converging nozzle through hich the burning propellant is passed.
`
`U.S. Patent No. 4,833,996 to Hayashi et al. describ s a gas generating apparatus for inflating
`
`an airbag which is circular and allegedly provides an nstantaneous pumping ratio of up to 7:1
`
`15
`
`although analysis shows that this is unlikely ~n the illust
`
`ted geometry. The average pumping ratio is
`
`specified to be up to 4:1. This invention is desi ned for the driver side of the vehicle where
`
`unrestricted access to the aspirating port might b difficult to achieve when mounted on a steering
`
`wheel. The propellant of choice in Hayashi et al. is sodium azide which requires extensive filtering to
`
`remove particulates. No attempt has been m de in this design to optimize the nozzle geometry to
`
`20 make use of a converging-diverging nozzle design, for example. Also, the inflator has a roughly
`
`conventional driver side shape. It is also in
`
`resting to note that no mention is made of valves to close
`
`off or restrict flow through the aspiration art during deflation. Since most aspiration designs having
`
`even substantially smaller pumping rj'os provide for such valves, the eliminatio-n of these valves
`
`would be a significant advance in thfart. Analysis shows, however, that the openmg needed for the
`
`25
`
`claimed aspiration ratios would in g neral be far too large for it also to be used for exhausting the
`
`ATI-65F.DOC
`
`7
`
`l
`
`15
`
`

`

`/tis is not discussed, it should be assL,
`
`~equired but
`
`not illustrated in the figures.
`
`,,\
`\
`
`U.S. Patent No. 4,877,264 to Cuevas describes an aspirating/venting airbag module/assembly
`/
`which includes a circular gas generator and contemplate·s the use of conventional idium azide
`
`I
`
`5
`
`propellants or equivalent. The aspiration or pumping ratio of this inflator is app/oximately .2:1,
`
`substantially below that of Hayashi et al., but more in line with aspiration syste s in common use
`
`today. This design also does not require use of aspiration valves which is m e reasonable for this
`
`case, but still unlikely, since the aspiration port area is much smaller. Ag in, no attempt has been
`
`made to optimize the nozzle design as is evident by .the short nozzle len h and the low pumping ratio.
`
`10
`
`U.S. Patent No. 4,909,549 to Poole et al. describes a proce
`
`for inflating an airbag with an
`
`aspiration system but does not discuss the aspiration design or
`
`chanism and merely asserts that a
`
`ratio as high as 4:1 is possible but assumes that 2.5:1 is avail ble. This patent is significant in that it
`
`discloses the idea that if such high pumping ratios are ob
`
`inable (i.e., 2.5:1 compared with .2:1 for
`
`inflators in use), then certain propellants, which wo d otherwise be unacceptable due to their
`
`15
`
`production of toxic chemicals, can be used. For e mple, the patent discloses the use of tetrazol
`
`compounds.
`
`It is interesting to note that there s yet is no commercialization of the Poole et al.
`
`invention which raises the question as to whe er such high aspiration ratios are in fact achievable
`
`with any of the prior art designs. Analysis as shown that this is the case, that is, that such large
`
`aspiration ratios are not achievable with t e prior art designs.
`
`20
`
`U.S. Patent No. 4,928,991 t Thorn describes an aspirating inflator assembly including
`
`aspiration valves which are gener y needed in all high pumping ratio aspiration systems. Sodium
`
`;1zide is the propellant used. P mping ratios of 1:1 to 1.5:1 are mentioned in this patent which by
`
`analysis is possible. It is note orthy that the preamble of this patent discloses that the state of the art
`
`of aspirating inflators yield pumping ratios of .1:1 to .5:1, far below those spec1fied in several of the
`
`ATI-65F.DOC
`
`8
`
`1
`
`16
`
`

`

`above referenced earlier p,
`
`Jts. Once again, little attempt has b'~~~· ade to optimize the nozzle
`
`design.
`
`. U.S. Patent No. 5,004,586 to Hayashi et al. describes a sotum azide driver side inflator in
`
`5
`
`which the aspirating air flows through a senes of annular -slots on; the Circumference of the circular
`I
`inflator in contrast to the earlier Hayashi et al. patent where the flow was on the axis. Similar pumping
`
`ratios of about 4:1 are claimed however, which by analysis is un~ely. Once again, aspiration valves
`
`I
`are not shown and the reason that they can be neglected is jnot discussed. An inefficient nozzle
`
`design is again illustrated. The lack of commercial success ithese two Hayashi patents is probably
`
`due to the fact that such high pumping ratios as claimed ari not in fact achievable in the geometries
`
`10
`
`illustrated.
`
`/
`
`U.S. Patent No. 5,060,973 to Giovanetti desc'lbes the first liquid propellant airbag gas
`
`generator wherein the propellant burns clean and does fot require filters to trap solid particles. Thus,
`
`it is one preferred propellant for use in the instant in(ention. This system however produces a gas
`
`which is too hot for use directly to inflate an airbag. /The gas also contains substantial quantities of
`I
`steam as well as carbon dioxide. The steam can ;r-ause burns to occupants and carbon dioxide in
`
`15
`
`significc:tnt quantities is toxic. The gas generatoiis also circular. Aspirating systems are therefore
`
`must be exhausted outside of the vehicle.
`
`required when using the liquid propellant discloled in this patent, or alternately, the gas generated
`I
`/
`;
`I
`U.S. Patent No. 5,129,674 to Levosins~i describes a converging-diverging nozzle design which
`I
`!
`provides for more efficient aspiration than sG)me of the above discussed patents. Nevertheless, the
`I
`
`airbag system disclosed is quite large and l)~ited in length such that the flow passageways are quite
`I
`large which requires a long nozzle design fr efficient operation. Since there is insufficient space for a
`
`20
`
`long nozzle, it can be estimated that this Jystem has a pumping ratio less than 1:1 and probably about
`
`.2:1. Once again a sodium azide basedrropellant is used.
`
`9
`
`ATI-65F.DOC
`
`{
`
`l
`
`17
`
`

`

`U.S. Patent No. 5,
`
`,450 to Pack, Jr. et al. describes/~"'
`
`.spirated air cushion restraint
`
`I
`
`system in which no attempt was made to optimize the nozzle design for this sodium azide driver side
`I
`
`airbag. Also, aspiration valves are used although it is suggest~d that the exhaust from the airbag can
`i
`' I
`be made through the aspirating holes thereby eliminating /the need for the flapper valves. No
`I
`analysis, however, is provided to prove that the area of thtspiration holes is comparable to the area
`
`5
`
`of the exhaust holes normally provtded tn the atrbag. Alt ough no mentton ts made of the pumping
`
`ratio of this design, the device as illustrated appear
`
`to be approximately the same size as a
`
`conventional driver side inflator. This, coupled with an analysis of the geometry, indicates a pumping
`
`ratio of less than 1:1 and probably less than .2: 1.
`
`he statement that the aspiration valves are not
`
`10
`
`needed also indicates that the aspiration ratio mus be small. Large inlet ports which are needed for
`
`large aspiration ratios are generally much larger t an the typical airbag exhaust ports.
`
`U.S. Patent No. 5,286,054 to Cuevas de cribes an aspirating/venting motor vehicle passenger
`
`airbag module in which the principal of operati n is similar to the '264 patent discussed above. Once
`
`again the aspiration pumping ratio of this
`
`vice is .15:1 to .2:1 which is in line with conventional
`
`15
`
`aspirated inflators.
`
`It is interesting to no
`
`that this pioneer in the field does not avail himself of
`
`desigm; purporting to yield higher pumpin
`
`ratios. Again the nozzle design has not been optimized.
`
`Other U.S. patents which are rei van