US005400487A.
`e
`5,400,487
`[11] Patent Number:
`United States Patent 1
`Gioutsos et al.
`[45] Date of Patent; Mar. 28, 1995
`
`
`[75]
`
`[54] VARIABLE INFLATION SYSTEM FOR
`5,209,510 5/1993 Mamiya .....sscsssscssssssesseeeese 280/735
`
`
`VEHICLE SAFETY RESTRAIN eeee
`
`al. resco
`320,
`tein
`et
`Inventors: Tony Gioutsos, Brighton; Edward J.
`oem
`Gillis, Canton: Leonard W. Behr,
`FOREIGN PATENT DOCUMENTS
`White Lake, all of Mich.
`3809074 10/1989 Germany oss 280/728 R
`[73] Assignee: Automotive Systems Laboratory, Inc.,
`SE16589
`5/1993)
`Japan ....esccsscsscssenseeseenens 280/734
`Farmington Hills, Mich.
`Primary Examiner—Margaret A. Focarino
`21] Appl. No.: 182.281
`Assistant Examiner—Peter C. English
`i 4 14. 1994
`oy ved °
`Attorney, Agent, orFirm—Lyman R. Lyon
`iled:
`.
`an.
`i
`ll
`it as
`57]
`ABSTRACT
`Ba) US.CTaaa/23s5280/73¢
`An inflation system (10)for a gas-operated vehicle oc
`cupant safety restraint, such as an air bag (12), com-
`180/282
`[58] Field of Search........... 280/735, 734, 736, 728 R:
`prises an accelerometer (14) and an infrared transceiver
`"480/282
`(20) for receiving vehicle acceleration information (a)
`and occupantposition information (x), respectively, for
`use by a processor (22) in selecting whichofa plurality
`of gas generators (28) willbe individually initiated, at
`selected actual timesto fire, in a selected order, to pro-
`vide optimal protection to the occupant in the event of
`a vehicle crash or marked vehicle deceleration.
`
`
`
`[56]
`
`.
`References Cited
`U.S. PATENT DOCUMENTS
`
`280/735
`5/1977 Held et ab.cesses
`4,021,057
`1/1981 Scholz et al.
`...
`se 280/735
`4,243,248
`3,067,744 11/1991 Hirabayashi ....
`wa. 280/734
`5,071,160 12/1991 White et al.
`....
`280/735
`5,074,583 12/1991 Fujita et al.
`280/735
`
`
`
`10 Claims, 2 Drawing Sheets
`
`
`
`PROCESSOR
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`U.S. Patent
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`Mar. 28, 1995
`
`Sheet 1 of 2
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`5,400,487
`
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`U.S. Patent
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`Mar. 28, 1995
`
`Sheet 2 of 2
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`5,400,487
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`Quantity(grams)ye
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`Bs
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`Quantity(grams)&®
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`i)
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`O
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`10
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`50
`20 30 40
`t (msec)
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`O
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`50
`10 20 30 40
`t (msec)
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`_ar. A._Fac. 8B.
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`re) 4 SS)
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`Quantity
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`(grams)
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`40
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`5,400,487
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`further correlate or otherwise qualify system response
`with the nature or severity of the crash and, hence,
`system response under Fujita et al fails to differentiate,
`for example, between a short-period, high-velocity
`crash and a long-period, low velocity crash (each of
`which requires substantively different inflator response,
`notwithstanding an identical relative occupant position
`within the vehicle).
`SUMMARYOF THE INVENTION
`
`VARIABLE INFLATION SYSTEM FOR VEHICLE
`SAFETY RESTRAINT
`
`BACKGROUND OF THE INVENTION
`
`5
`
`Theinstant invention relates to systems for deploying
`gas-operated vehicle occupant safety restraints, such as
`vehicle air bags, which seek to optimize occupant pro-
`tection notwithstanding variations in occupantsize and-
`/or position within the vehicle at the time at which
`safety restraint deploymentis otherwise deemed advis-
`able.
`The priorart teaches inflation systems for deploying
`an air bag in a motor vehicle which typically include a
`single gas generator in fluid communication with the
`interior of the uninflated air bag. In the typical embodi-
`ment, the gas generatoris triggered by an air bag firing
`circuit when the sensed vehicle acceleration exceeds a
`predetermined threshold value, as through theuse of an
`acceleration-responsive inertial switch and an explosive
`“squib.”
`In a variation upon this design, U.S. Pat. No.
`4,928,991 to Thorn teaches an aspirating inflator assem-
`bly for a vehicle occupant restraint which employs a
`plurality of low cost gas generators to achieve an in-
`creased aspiration ratio. Each of Thorn’s identical gas
`generators has an identical output characteristic, ie.,
`generate a like quantity of gas effluent over a like
`amountof time; and the basic manner in which each gas
`generator is triggered remains the same, ie., a “fire”
`signal for each gas generatoris itself generated when
`the sensed acceleration exceeds a predetermined thresh-
`old value, thereby identifying the time at which each
`gas generatoris to be triggered (sometimes referred to
`as its “actual time-to-fire” or “actual TTF”). Thorn
`further suggests that the use of multiple gas generators
`permits the adapting of the inflator assembly output
`characteristic to the conditions of the crash,i.e., vehicle
`velocity, ambient temperature, occupant size and/or
`position or other condition, presumably based upon
`values therefor as measured at the time that the “fire”
`signal is generated, by triggering the ignition of only
`some of the inflator assembly’s multiple gas generators.
`Stated another way, under Thorn,a fire signal is gener-
`ated by the firing circuit based solely upon received
`vehicle acceleration information, at which time the
`initiation of each gas generatoris selectively triggered
`to provide a plurality of inflator responses.
`In U.S. Pat. No. 5,074,583, Fujita et al teach an air
`bag system for an automobile which employs accelera-
`tion data to detect a vehicle collision or marked deceler-
`ation requiring deployment of the air bag. The system
`further controls when and how quicklyto inflate the air
`bag upon such detection of a vehicle collision or
`marked deceleration based on occupantposition as it is
`indirectly garnered from the occupant’s “seating condi-
`tion,” i.e., the longitudinal position of the seat within
`the vehicle, the reclining angle of the seat back, pres-
`sure sensors in the seat and seat back, etc. Thus, as
`under the above Thorn patent, under Fujita et al, once
`a “fire” signal is generated by the system’s firing circuit,
`the system attempts to further adjust the nature of the
`response,i.e., the mannerin whichtheair bagis actually
`inflated, in response to indirectly-sensed occupantposi-
`tion data. Thereis no attempt to adjust the actual TTF,
`ie., the time at which the “fire” signal is itself gener-
`ated, based on the nature or severity of the crash experi-
`enced by the vehicle. Nor do Fujita et al attempt to
`
`It is an object of the instant invention to provide an
`inflation system for a gas-operated vehicle occupant
`safety restraint, such as an air bag, which adapts the
`mannerin which therestraint is inflated so as to maxi-
`mize its effectiveness for an occupant in any given posi-
`tion within the vehicle and for any given crash type.
`A further object of the instant invention is to provide
`an inflation system for a gas-operated vehicle occupant
`safety restraint, such as an air bag, which employs a
`selected one of a plurality of inflation profiles as deter-
`mined by an occupant’s relative position within the
`vehicle and the nature or type of the crash therein-
`volved, with each inflation profile featuring a different
`bag inflation rate and/orinflation pressure, wherebyair
`bag inflation may be tailored to maximize restraint ef-
`fectiveness.
`In accordance with the instant invention, an inflation
`system for a gas-operated vehicle occupant safety re-
`straint, such as an air bag, comprises a first means for
`receiving information representative of instantaneous
`vehicle acceleration; a second means for receiving in-
`formation indicative of instantaneous occupant position
`relative to a fixed interior structure; and a processor
`means, responsive to the received vehicle acceleration
`information and the received occupant position infor-
`.Mation, for determining a first measure representative
`of crash type using the received vehicle acceleration
`information, and for determining a desired inflation
`profile using the first measure representative of crash
`type and the received occupant position information. In
`accordancewiththe instant invention, while the proces-
`sor means determines the first measure and, correla-
`tively, the desired inflation profile, the processor means
`is simultaneously determining a first actual timeto fire
`using the received vehicle acceleration information.
`Finally, the instant system further includes actuating
`means, responsiveto thefirst time to fire and the desired
`inflation profile, for generating a gas effluent in accor-
`dancewith the desired inflation profile at the first time
`to fire. In the preferred embodiment,
`the actuating
`means comprises an inflator assembly having at least
`two individually-triggerable gas generators, wherein
`one of the gas generators has a different output charac-
`teristic than another of the gas generators.
`In operation, the instant system receives information
`as to vehicle acceleration and occupant position and,
`upon discriminating a crash condition requiring deploy-
`ment of a safety restraint while otherwise determining
`the probable crash-type, the system selectively triggers
`individual gas generators to tailor theinflation profile to
`meet those conditions.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`FIG. 1 is a biock diagram ofthe instant variable infla-
`tion system for inflating a vehicle air bag;
`FIGS.2a and 20 are plots of the total quantity of gas
`generated over time by a first gas generator (A) and a
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`second gas generator (B) controlled by the instant sys-
`tem, respectively, as measured from the time of their
`ignition; and
`FIG. 3 contains exemplaryplots of the total quantity
`of gas generated over time by the instant system under
`four different inflation profiles (W, X, Y and Z), as
`selected using measures representing crash-type and
`occupantposition from four different scenarios, as mea-
`sured from the commencementof a crash event.
`
`DETAILED DESCRIPTION OF THE
`PREFERRED EMBODIMENT(S)
`Referring to FIG.1, an inflation system 10 for a gas-
`operated vehicle occupant safety restraint, such as an
`air bag 12, comprises a first means, such as an acceler-
`ometer 14, for receiving information a representative of
`instantaneous vehicle acceleration, which acceleration
`informationis supplied as digital acceleration data 16 to
`a data storage means, such as a RAM 18; a second
`means, such as infrared transceiver 20, for receiving
`informationx indicative of instantaneous occupantposi-
`tion; processor means 22 responsive to the acceleration
`data 16 stored in the RAM 18 and theinstantaneous
`occupant position information for generating at least
`one trigger signal 24 based on the acceleration data 16
`and the instantaneous occupant position information;
`and actuating means,suchasair baginflator 26, respon-
`sive to the at least one trigger signal 24 for deploying
`the safety restraint 12, wherein the inflator 26 includes
`at least two individually-triggerable gas generators 28
`responsive to theat least one trigger signal 24 generated
`by the processor means 22, respectively, with at least
`one of the gas generators 28 having a different output
`characteristic than the other gas generators 28.
`Undertheinstant invention, the output characteristic
`of the inflator 26 as a whole—its “inflation profile”—is
`defined by the timing of and particular order in which
`eachofits gas generators 28 is selectively triggered by
`the processor 22, whichitself is a function of both the
`crash type (as extrapolated from past received accelera-
`tion data) and the occupant position (as indicated by
`present received occupantposition data).
`The Table below comprises a matrix providing exem-
`plary values for the preferred actual times to fire TTF4
`and TTFsfor each of two dissimilar gas generators A
`and B whose hypothetical outputs are plotted in FIGS.
`2a and 28, respectively. The output characteristic for
`gas generatorA,i.e., the quantity of gas effluent gener-
`ated by gas generator A over time, provides fora rela-
`tively rapid and, hence, relatively “hard” inflation of
`the air bag 12; whereas the output characteristic of gas
`generator B provides for a relatively slower and, hence,
`relatively “softer” air bag inflation.
`For the purpose of discussing the contents of the
`Table, it will be assumed that there are only these two
`gas generators A and B in the subject inflator; and that
`the actual times to fire appearing in the Table will pro-
`vide the optimal inflation profile for a given combina-
`tion of crash type and occupant position, for a given
`vehicle. The crash types appearing in the Table are
`nominally defined as follows: a small ON-condition
`crash is one generating an impact velocity of 15 MPH:
`a moderate ON-condition crash is one generating an
`impact velocity of 20 MPH;and a severe ON-condition
`crash is one generating an impact velocity of perhaps 25
`MPH.
`
` 4
`
`Small ON-
`Condition
`Crash
`
`Moderate ON-
`Condition Crash
`
`Severe ON-
`Condition Crash
`
`5
`
`10
`
`15
`
`20
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`40
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`aA0
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`35
`
`60
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`65
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`Near TTF4= 45 msec TTF4= 20msec TTF, = 10 msec
`Occu-
`pant
`Posit TFs = 30 msec TIFg = 25 msec TIFg = 10 msec
`tion
`Nom- TTF4= 50 msec TIF4= 30 msec
`inal
`Occu-
`pant
`Posi-
`tion
`Far
`Occu-
`pant
`TITFg = 55 msec TIFg = 35 msec TIFg = 30 msec
`Posi-
`tion
`
`TITFg = 40 msec TIFg = 30 msec TIFg = 20 msec
`
`TYF4= 60 msec TIF4=40msec TIF, = 20 msec
`
`TTF4 = 15 msec
`
`It must be emphasized the above Table provides pre-
`ferred actual timesto fire for each of the two gas gener-
`ators thereinvolved, for purposes ofillustration only.
`Conceptually speaking, to obtain the desired inflation
`profile using the values in the Table, the ignition of each
`gas generator could be triggered by the crash discrimi-
`natorat the actual time to fire prescribed therein. Under
`the more practical approach employedin the preferred
`embodiment of the instant system 10, however,
`the
`processor 22 determines a single actual timeto fire upon
`application of its crash discrimination analysis to the
`received vehicle acceleration information a (as perhaps
`further supplemented using the received occupantposi-
`tion information x), whereupon the processor 22 checks
`the currently selected inflation profile to determine
`which of the gas generators 28 is then designated as
`properly being the first of the gas generators 28 to be
`ignited (noting further that the optimal inflation profile
`may designate two or more gas generators 28 as prop-
`erly being the first gas generator 28 to be ignited,i.e.,
`the inflation profile designates simultaneous ignition of
`those two or more gas generators 28). The processor 22
`then proceeds to trigger ignition of the heretofore-
`designated-first-to-be-ignited gas generator 28. Thereaf-
`ter, additional gas generators 28 are individually and
`selectively ignited after a time delay equal to the differ-
`ence between the additional gas generators’ prescribed
`actual timeto fire less the first-to-be-ignited gas genera-
`tor’s prescribed actual timeto fire, thereby effectuating
`the optimal inflation profile. It is noted that the ap-
`proach of the preferred embodiment
`is particularly
`well-suited for systems employing a large numberof gas
`generators 28 and, hence, which provide an even
`greater number of combinations and permutations in
`accordance with which the individual gas generators 28
`may be ignited. In this manner, the response of the
`inflator 26 is adjusted to provide a selected one of the
`available inflation profiles available by virtue of the
`various combinations and permutations of individually
`triggering the gas generators at sameordifferent TTFs.
`FIG. 3 contains exemplary plots of the total quantity
`of gas generated overtime by the instant system under
`four of the different inflation profiles found in Table.
`Specifically, where analysis of the received acceleration
`information prior to generation of the trigger signal
`further indicates the occurrence of a relatively severe
`crash, while the received occupant position information
`indicates an assumed position relatively near to the
`inflator as of the moment whenthe trigger signal
`is
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`generated, the instant system determines the appropri-
`ate inflation profile W as requiring simultaneous igni-
`tion of both individual gas generators at a prescribed
`actual TTF of 10 msec so as to provide a very steep
`inflation profile or “S-curve’”to inflate the air bag very
`rapidly.
`And, where analysis of the received acceleration
`information prior to generation of the trigger signal
`further suggests that the vehicle is experiencing a rela-
`tively moderate crash, while the received occupant
`position information indicates that the occupant has
`assumed a position within the vehicle very near the
`restraint, the instant system would provide an inflation
`profile X featuring a hybrid S-curve having a gradual
`slope up followed bya steep rise in pressure over time,
`ie., a relatively “soft” initial inflation followed by a
`relatively “harder” one. Specifically, this inflation pro-
`file X would be achieved by triggering ignition of gas
`generator A at an actual time to fire of 20 msec, with gas
`generator B being subsequently ignited after a further
`delay of 5 msec.
`Where analysis of the received acceleration informa-
`tion prior to generation of the trigger signal suggests
`that the vehicle is experiencing a relatively small but
`significant crash, and the occupantis detected as being
`relatively near the uninflated air bag, gas generator B
`would first be ignited at an actual time to fire TTFg of
`30 msec, with gas generator A being ignited some 15
`mseclater, illustrated as inflation profile Y in FIG. 3.
`And, where analysis of the received acceleration
`information suggests that the vehicle is experiencing a
`relatively small but significant crash, but the occupantis
`detected as being relatively far away from the unin-
`flated air bag, gas generator B wouldfirst be ignited at
`an actual time to fire TTF, of 55 msec, with gas genera-
`tor A being ignited some 5 mseclater, illustrated as
`inflation profile Z in FIG.3.
`As a final example (not shown in FIG. 3), where
`analysis of the received acceleration information a prior
`to the discrimination of a crash condition requiring
`deployment of the air bag suggests that the vehicle is
`experiencing a severe crash, but the received occupant
`position information x indicates an assumed position
`whichis particularly far-removed from the uninflated
`air bag, the instant system would provide an inflation
`profile featuring a hybrid S-curve having a gradual
`slope up followed by a steep rise in pressure over time,
`ie., a relatively “soft” initial inflation followed by a
`relatively “harder” one.
`Asa final note regarding to the Table, it should be
`pointed out that a truly “robust” system would not
`resort to a lookup table to obtain the actual TTFs corre-
`sponding to a given inflator profile but, rather, would
`be monotonic in its approach. Thus, where a delta ve-
`locity crash of 20 MPH is encountered (nominally a
`“moderate ON-condition crash”) while an occupantis
`positioned 10 inches from the dash (a “near occupant
`position”’), the Table supplies actual times to fire of 20
`msec and 25 msec for gas generators A and B, respec-
`tively. Now suppose the occupantis seated at the same
`position, but a 22 MPHcrash is encountered. The sys-
`tem should preferably prescribe an actual timeto fire of
`18 msec for gas generatorinflator A and 21 msec for gas
`generator B.
`Finally, it is noted that crash type and transitory
`occupant position remain significant measures even
`after the processor 22 triggers ignition of the first of the
`gas generatorsat the actual time to fire generated by the
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`crash discrimination analysis. Accordingly, such subse-
`quent crash type and transitory occupant position mea-
`sures may thereafter be analyzed and the optimal infla-
`tion profile subsequently adjusted (as by shortening or
`lengthening the then-prescribed time delays relating to
`further ignition of the remaining gas generators 28),
`thereby further improving the response of the instant
`system 10.
`While the preferred embodimentof the invention has
`been disclosed, it should be appreciated that the inven-
`tion is susceptible of modification without departing
`from the spirit of the invention or the scope of the sub-
`joined claims. For example, while the preferred em-
`bodiment discussed hereinabove relates to the deploy-
`ment ofan air bag,it will be readily appreciated that the
`invention may be used with other gas-operated safety
`restraints, e.g., seat belt pretensioners, which may be
`adapted to employ multiple gas generators to provide
`variable and/or multistage response.
`Weclaim:
`1. A system for generating a gas effluent for inflating
`a gas-operated vehicle occupant safety restraint com-
`prising:
`a first means for receiving information representative
`of instantaneous vehicle acceleration;
`a second meansfor receiving information indicative
`of instantaneous occupant position relative to a
`fixed structure within the vehicle;
`a processor means, responsive to the received vehicle
`acceleration information and the received occu-
`pant position information, for determining a first
`measure representative of crash type using the
`received vehicle acceleration information, wherein
`said processor means further determines a desired
`inflation profile using the first measure representa-
`tive of crash type and the received occupant posi-
`tion information, and wherein said processor means
`simultaneously determines a first actual time to fire
`using the received vehicle acceleration informa-
`tion; and
`actuating means, responsive to the first time to fire
`and the desired inflation profile, for generating a
`gas effluent in accordance with the desired infla-
`tion profile at the first time to fire.
`2. The system of claim 1, wherein said actuating
`means includes an inflator assembly having at least two
`individually-triggerable gas generators, wherein one of
`the gas generators has a different output characteristic
`than another of the gas generators, and wherein the
`desired inflation profile selects which of said at least
`two gas generators is triggered at the first timeto fire.
`3. The system of claim 2, wherein said inflation pro-
`file further selects which of said at least two gas genera-
`tors is triggered after the first time to fire at a second
`timeto fire.
`4. The system of claim 3, wherein the second time to
`fire is defined by the desired inflation profile relative to
`the first time to fire, whereby the secondtimetofire is
`a selected time delay after the first time to fire.
`5. The system of claim 4, including means responsive
`to the received vehicle acceleration information or the
`received occupant position information for adjusting,
`after the first timeto fire, the selected time delay.
`6. The system of claim 1, wherein said processor
`means is further responsive to the received occupant
`position information when determining thefirst time to
`fire using the received vehicle acceleration information.
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`7. The system of claim 6, wherein said actuating
`means includesan inflator assembly havingat least two
`individually-triggerable gas generators, wherein one of
`the gas generators has a different output characteristic
`than another of the gas generators, and wherein the
`desired inflation profile selects which of said at least
`two gas generatorsis triggered at the first time tofire.
`8. The system of claim 7, wherein said inflation pro-
`file further selects whichofsaid at least two gas genera-
`
`8
`tors is triggered after the first time to fire at a second
`timeto fire.
`9. The system of claim 8, wherein the second time to
`fire is defined by the desired inflation profile relative to
`the first time to fire, whereby the secondtimetofire is
`a selected time delay after the first timeto fire.
`10. The system of claim 9, including means respon-
`sive to the received vehicle acceleration information or
`the received occupant position information for adjust-
`ing, after the first time to fire, the selected time delay.
`*
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