‘
`
`e
`
`3,944,769
`(1
`United States Patent
`[45] Mar. 16, 1976
`Wagner
`
`
`115;
`
`HOUSEr neeeessessccccssesssseessooe 200/83 B
`12/1967
`3,359,388
`[54] PRESSURE SENSING MEANS AND
`preenwoodseertseenenneesnsnnn aoeeaos
`anoys
`*I58eee
`METHOD FOR MAKINGA PRESSURIZED
`
`3728,
`ceeceeteesseneenee
`AKOTA... eee
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`CONTAINER MEANS AND SYSTEM S/1973)0Kermer oe.ceecccceseescsseees 200/83 R3,735,376
`
`UTILIZING THE SAME
`3,818,764
`6/1974 Wagne reeesceereseneen 280/150 AB
`Inventor:
`Joseph P. Wagner, Knoxville, Tenn.
`{75]
`:
`[73] Assignee: Robertshaw Controls Company,
`Richmond, Va.
`Sept. 25, 1974
`[22]. Filed:
`[21] Appl. No.: 509,009
`:
`er
`. Related USS. Application Data
`[63] Continuation of Ser. No. 321,648, Jan. 8, 1973,
`abandoned.
`[52] US. Cl...........5otete ports393; 200/83 B;
`[51]
`Int. Cl?
`fi
`; 280/150 HOH36/34
`feeeens
`[58] Field of Sean a3aa or 200/83 J, 83 N,
`I 340, 84 R, 61.25, 61.26,
`/242, 73/393, 407 R
`.
`References Cited
`UNITED STATES PATENTS
`4/1928
`Siddal oo... eeescseseeseseens 200/83 N
`
`4/1948 Cressey...cece 200/83 J X
`6/1958 W00dcrceecccsecccosscscssessssessese 200/83 C
`
`4/1966
`Boetttinger «....eesescsesceeseee 200/83 N
`
`2/1967. Coopericsccsccessessssessscecessses 200/83 B
`
`Primary Examiner—M. H. Wood,Jr.
`Assistant Examiner—John P.Silverstrim
`Attorney, Agent, or Firm—Candor, Candor & Tassone
`.
`ABSTRACT
`[57]
`A pressure sensing means having a housing provided
`with a chamber therein. A double wall fluid operated
`device is disposed in the chamber of the housing and
`is carried by the same, the walls of the device defining
`a chamber therebetweenthat is interconnected to the
`exterior of the housing by a passage. A charge of pres-
`sure fluid is sealed in the chamber of the housing to
`initially hold the walls of the device in flat abutting re-_
`lation in a manner to prevent an adverse permanent
`set thereof. Subsequently, the chamber of the double
`wall fluid operated device is interconnected to the
`pressurized chamberof a container meansfor a vehic-
`ular air bag safety system whereby the pressure sens-
`ing means can subsequently detectloss or gain of pres-
`sure differential across at least one of the walls of the
`double wall operated device for detection purposes or
`thelike.
`.
`oo
`3 Claims, 6 Drawing Figures
`
`[56]
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`U.S. Patent March 16, 1976
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`|
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`3,944,769
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`1
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`3,944,769
`
`PRESSURE SENSING MEANS AND METHOD FOR
`MAKING A PRESSURIZED CONTAINER MEANS
`AND SYSTEM UTILIZING THE SAME
`This is a continuation of application Ser. No.
`321,648, filed Jan. 8, 1973, now abandoned.
`This invention relates to an improved pressure sens-
`ing device and to a method for making such a pressure
`sensing device as well as to a pressurized container
`means and method for making the same.
`It is well known that a vehicularair bag safety system
`has now been provided wherein an inflatable bag is
`normally disposed in a flat, out of the way condition
`and is adapted to be almost instantaneously inflated by
`fluid pressure upon an impact of a vehicle with a harm
`producing object so as to protect one or more individu-
`als in the vehicle being engaged by the thus inflated
`bag. In order to inflate such safety air bag, a container
`means mustbe provided for the storing of such inflating
`fluid under pressure and in order for the system to
`function properly,
`the pressure in such container
`‘means must not increase or decrease beyond a prede-
`termined amount when that container meansis at a
`certain temperature.
`For example, such fluid storage container means can
`each be charged with an inert gas, such as argon, he-
`lium, and the like, or a mixture of the same, to approxi-
`mately 2400 psi at room temperature and such con-
`tainer means must be adapted to maintain the stored
`gas pressure so that the same does not drop by more
`than approximately 200 psi or does not gain more than
`approximately 200 psi when at that same room temper-
`ature. Of course, such limits, as well as others hereinaf-
`ter set forth, are by way of example only and are not
`intended in any manner to place restrictions on the
`scope of the claimed invention.
`It is feature of applicant’s concurrently filed patent
`application, Ser. No. 322,071, filed Jan. 8, 1973, now
`U.S. Pat. No. 3,818,764 and entitled PRESSURE
`SENSING MEANS AND METHOD FOR A PRES-
`SURIZED CONTAINER MEANS AND SYSTEM
`UTILIZING THE SAME,to provide a meansfor de-
`tecting any adverse loss or gain in the pressure in such
`pressurized container means caused by means other
`than temperature change, such as pressure changes
`that are caused by a leak in the container means or
`other damage of the container means.
`In particular, one embodimentof the invention of the
`aforementioned pending patent application comprises
`a fluid operated sensing meanscarried by the container
`means in such a mannerthat the sensing meansis sub-
`stantially surrounded by a reference pressure of the
`fluid of the container means so as to be temperature
`compensated thereby whereby any pressure changes of
`the fluid in the container means caused by temperature
`changes thereof are ineffective to cause a sensing
`thereof by the sensing meansasthe fluid of the sensing
`meansis always at the same temperatureasthe fluid in
`the container means. Such sensing means comprises a
`fluid operated means having a movable wall inside the
`container meanswith that movable wall being changed
`by the pressure differential acting across the same and
`operating an electrical switch of a signal meanstoindi-
`cate when the pressure in the container means has
`changed from the desired value thereof to an undesired
`value thereof by means other than temperature change
`thereof.
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`Thus, under extreme temperature variation condi-
`tions of the storage area for the fluid storage container
`for the vehicle air bag safety system, even though the
`sameis inside the passenger compartment, the temper-
`ature of the fluid in the container means can reach
`approximately 220° F or minus 20° F and under these
`abient temperature conditions, the pressure within the
`container means can build to 3400 psi or go as low as
`1700 psi at the extreme temperature conditions thereof
`even though the same is approximately 2400 psi at
`room temperature. However, the sensing device of the
`aforementioned copending application is temperature
`compensated by the fluid of the containeritself, so that
`the temperature of the fluid operated sensing deviceis
`the same as the temperature of the fluid in the con-
`tainer means. Thus, such pressure changes caused by
`extreme temperature conditions will not cause a false
`indication that the pressure within the container means
`has been adversely affected by means other than tem-
`perature.
`The aforementioned copending patent application
`teaches that the fluid in the sensing means mustinitially
`be at the same pressurelevel as the pressurelevelof the
`fluid initially charged into the main container means
`and, such copending patent application states that the
`sensing means and the container meanscan be simulta-
`neously charged with the same fluid and to the same
`pressure level.
`However,it has been found according to the teach-
`ings of this invention that it may be desirable to charge
`the sensing means with the its fluid remote from the
`main container meansso that such percharged sensing
`means can thereafter be assembled inside the container
`meansfor the previously mentioned temperature com-
`pensating purposes with the container means subse-
`quently being charged with its fluid independently of
`the precharging of the sensing means andstill have the
`sensing means performits function of thereafter detect-
`ing any loss in the pressure in the main container means
`caused by a leak of fluid from the main container
`means or other damage thereof as will be apparent
`hereinafter.
`Accordingly, it is a feature of this invention to pro-
`vide an improved pressure.sensing means that can be
`precharged with its pressure fluid and whichwill not be
`adversely affected thereby, such as by being given an
`adverse permanentset by such percharging thereof, so
`that the same can thereafter beutilized with a pressur-
`ized container means
`to sense pressure changes
`therein.
`In particular, one embodimentofthis invention pro-
`vides a sensing means having a housing meansprovided
`with a chambertherein. A: double wall fluid operated
`device is disposed in the chamberof the housing means
`and is carried by the same, the walls of the device defin-
`ing a chamber therebetween that is interconnected to
`the exterior of the housing meansby a passage means.
`A charge ofpressure fluid is sealed in the chamber of
`the housing meansand since the chamberof the double
`wall fluid operated device in an atmospheric condition,
`the pressure ofthe fluid in the chamberofthe housing
`means holds the walls of the device in a collapsed abut-
`ting condition. Since both walls are moved toward each
`other by the surroundingfluid pressurein the chamber
`of the housing means so as to be held in intimate
`contact against each other, no adverse permanentsetis
`provided on the walls of the fluid operated device even
`though the percharged sensing means is stored for a
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`relatively long period of time. Such sensing means can
`theréafter.be assembled inside the container meansof a
`vehicularair bag safety system and the container means
`can be subsequently charged with pressurefluid to the
`desired level thereof which, according to the teachings
`of this invention, is to substantially the same pressure
`level as the pressurelevel of the precharged fluid that is
`sealed in the chamber of the housing means of the
`sensing means whereby the chamberinside the fluid
`operated device is now interconnected to the fluid
`pressure in the main:container meansand will cause the
`movable walls thereof to expand outwardly to a certain
`position’ because of the resulting pressure differential
`now acting across such walls.
`Whenthe pressure differential across the walls of the
`sensing means‘is at an.acceptablelevel, one. of the walls
`of the fluid operating device can be utilized to make
`contact. witha contact means.so as to continuously
`indicate that the pressure level within the main con-
`tainer meansis at.an acceptable level. However, should
`the pressure differential acting across such wall of the
`fluid operated device increase becauseofa loss of fluid
`pressure in the main container means, such as through
`a.leak thereof or the like, such movable wall will move
`away from the contact means bysuch resulting increase
`in pressure differential across the.same and thereby
`interrupt anelectrical circuit so that an indicator or
`alarm will be activated to provide means forindicating
`that the pressure level within the main container means
`has ‘fallen below an acceptable level for safe operation
`-of the vehicular air bag safety system.
`- Therefore, it is an object of this invention to provide
`an improved pressure sensing means having one or
`more of the novel features. of this invention as set forth
`above or hereinafter:shown in described:
`Another. object of this invention is to provide a
`method for making sucha fluid operated pressure sens-
`ing means..
`--
`-
`'- Another object of this invention is to provide an
`‘improved pressurized container means for a vehicular
`air ‘bag'safety. system and thelike.
`Another object of this invention is
`to provide a
`‘methodfor:making such a pressurized container means
`orthe like.”
`: Other objects, uses and advantages of this invention
`‘ are apparent from the readingof this description which
`proceeds with reference to the accompanying drawings
`-showing apart thereof and wherein:
`FIG. 1 is:a schematic view illustrating the vehicular
`air bag safety system of this invention.
`.FIG..2 is a side view of the improved. fluid operated
`‘ pressure sensing meansofthis invention.
`FIG.
`3.
`is an enlarged, cross-sectional view taken
`substantially:on line 33 of FIG. 2, FIG. 3 illustrating
`the fluid operated pressure sensing means before the
`same has been charged with its fluid.
`FIG. 4 is a.view similar to FIG. 3 and illustrates the
`«fluid. operated pressure sensing means after the same
`has been precharged with its fluid.
`. FIG. 5 is a view similar to FIG. 4 and illustrates the
`fluid operated pressure sensing meansof this invention
`after. the same has been disposed within a main con-
`tainer means that has also been subsequently charged
`with its pressure fluid.
`FIG. 6 is a fragmentary schematic view illustrating
`‘how thepressure sensing meansofthis invention can be
`‘mounted within the main container means and can be
`utilized to indicate loss of. pressure therein.
`
`4
`While the various features of this invention are here-
`inafter described and illustrated as being particularly
`adaptable for providing pressure sensing meansfor the
`pressurized container means of a vehicular air bag
`safety means, it is to be understood that the various
`features of this invention can be utilized singularly or in
`any combination thereof to.provide fluid operated
`sensing means for other devices. as desired.
`Therefore, this invention is not to be limited to only
`the embodimentillustrated in the drawings, because
`the drawings are merely utilized toillustrate one of the
`wide variety of the. uses of this invention.
`Referring now to FIG. 1,.a vehicular air bag safety
`system is generally indicatedby the reference numeral
`20 and comprises an air bagstructure 21 adapted to be
`normally stored.in a collapsed out of the way condition
`but being adapted to be substantially instantaneously
`inflated as schematically illustrated in FIG. 1 by being
`fluidly interconnected toa pressurized container means
`22 by suitable means 23 that is actuated by an impact
`of the vehicle against a harm producing object in a
`mannerwell knownin the art wherebythe details of the
`same need not be further described in order to under-
`stand thefeatures of this invention.
`The system 20 of. this invention includes a signal
`producing device 24, such as analarm, lamp, or other
`indicator which will be activated by the pressure sens-
`ing means of this invention in a mannerlater to be
`described when the pressure sensing means detects an
`adverse changein the pressure of the fluid in the stor-
`age container means 22.
`,
`Asillustrated in FIGS. 2 and 3, the pressure sensing
`means of this invention is generally indicated by’ the
`reference numeral 25 and comprises. ahousing means
`26 that can be formed from a pair of parts 27 and 28
`assembled together to provide a chamber 29 therebe-
`tween and within the housing means 26. While the
`housing part 28is illustrated as being formed ofelectri-
`cally insulating material, it is to be understood that the
`same could bé formed ofelectrically conductive mate-
`rialif desired as will be apparent hereinafter.
`A double wall fluid operated device that is generally
`indicated by the reference numeral 39 is disposed
`within the chamber 29 of the housing. means 26 andis
`carried by the same, the device 30 comprising a pair of
`annular cup-shaped diaphragm walls 31 and 32 respec-
`tively being secured together at their outer peripheries
`33 and 34 in a mannerwell knownin the art and being
`adapted to define a chamber 36 therebetween.
`The walls 31 and 32 are respectively corrugated by a
`plurality of annular flutes 35 which are adapted to
`intimately. and readily nest within one another in the
`mannerillustrated in FIG. 4 for a purpose hereinafter
`described.
`:
`The wall 32 of the device 30 hasits central portion 76
`secured to a tubular member 37 sealed through an
`opening 38 in the housing part 28 whereby the tubular
`member 37 carries the double wall device 30 and since
`the tubular member37 is securedto the housing means
`28 and has an enlarged annular part 39 disposed within
`the chamber 29 so that the same cannot, pass through
`the opening 38 in the housingpart 28, the tubular part
`37. secures the device. 30 to the housing means 26
`within the chamber 29 thereof. The tubular member 37
`has a passage 40 passing longitudinally therethrough
`and being aligned with an opening 41 formed through
`the central part 76 of the wall 32 sothatthe passage 40
`is in fluid communication with the chamber 36 of the
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`terminal 55 that projectsoutofthe container means 22
`‘andiselectrically. insulatedtherefrom byanelectrically
`‘insulating plug 56:which. also carries: another, terminal
`57 in-electrically spacéd relation :to..the: terminal. 55.
`:Fhe-terminal.55 isadapted to beinterconnected by a
`-lead'58 to oneside 59 oftheindicatingdevice 24 while
`-the: other’ sidé 60 thereof is adapted tobe -intercon-
`‘nected by a lead‘ 61 to‘ oneside.62 of:an electrical
`power source 63, such as the automobile battery thatis
`illustrated. ‘The other: side. 64 of :the electricalpower
`source63 is adapted to beinterconnected by the: lead
`‘65 ‘to the terminal.’57:.The:terminal: 57, in-turn,
`is
`adapted’ to be “interconnected by-the- iead 66 to the
`‘tubular’ member 37of the Sensing device 30- whereby
`“theside 64 ofthe: power: source 63:is,:in effect, electri-
`‘allyinterconnected to. the wall:31 of the. device: 30
`whiletheterminalrod 45is electrically interconnected
`to theother side*62 ofthe power source 63.-:
`~ The indicator:24isso: constructed.and arranged that
`the sameindicates that the system is safe: aslong as an
`-electrical current passes therethrough so that. when the
`“electrical current passing throughthe:indicator: 24. is
`“broken, the same indicates that: an- unsafe condition
`
`“herérinafter: described:,
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`devicé'30and,thus,‘fluidly interconnécts the:chamber
`36'ofthe device 30to the exterior‘ofthe housingmeans
`‘26fora' purpose hereinafter desoribed:.
`:
`«The othér’wall:32‘of the device’30:;has.its: central
`‘portion 42: formed in’ a:cup shape to:;provide-a.flat ©
`circular part‘43 extending completely: beyond:theflutes
`35 of thewall 31 so:as. to bé adapted:to. abut against:a
`flat end 44of a terminal rod 45 havingits upperend 46
`“projecting:intothe chamber‘29 ofthe sensing ineans 25
`in’ the‘manner: illustrated.in FIG.5 for:athe, purpose ‘
`--The:terminal rod 45 is securedtothe housingpart27
`while being electrically insulated therefromby an elec-
`-trically insulating sleeve.47.sothat the upper.end 46,of
`the tod 45: projects. into the.chamber.29 and the lower
`end 48thereof projects out of:‘the housingmeans26for
`lead attachment:‘Purposes.as.willbeapparent hereinaf-
`ter. :
`ey
`The.terminal “rod.45.is assembledto:the‘housing
`means26 jin such.a mannerthat the uppersurface44 of
`the upper. end 46 ofthe rod45 is slightly spaced from
`. thesurface43of thewall.31of the device-30 when.the
`chamber29 ofthe housingmeans.26 and the chamber
`-36. ofthe device 30. are atatmospheric conditions,as.
`illustrated.jn FIG. 3 for;a.purpose|hereinafter,de-
`scribed..
`cay
`-_
`.Thehousing’part28 carriesa filtube 49‘thathas’its
`passage means. 50. in uid.communica' ion|with the
`
`chamber29ofthe housing means 26.
`After the pressuresensing meanshas been assembled
`inthe. mariner illustrated in FIG.3, the chamber 29
`thereofisadapted to be‘precharged \with|pressure fluid
`
`and
`ssure levelthat’is substantially1thé'same'as
`thedesired pressure level thatiis‘to be maintained in‘the
`main container means ‘22 of the’‘air ‘bagsafety system
`20.Itis, preferred thatthe fluid being ‘chargedirito the
`chamber 29 ofthe’sensing:meaiis ‘25° throughthefill
`
`‘tube49 beof hesame typeoffluidthatiistobe utilized
`in the main'containermeans 22,'In any.event,after the
`chamber"29°hasbeencharged’‘to’the’‘predetermined ‘
`" pressure‘level thereof,‘the fill tube’ 49 is sealed ‘closed
`, by any|suitable means; such as'bythe'welding51 ‘illus-
`“tratedin"FIG; 4 whereby the ‘charge’bf!présstre’fluid
`within the‘Chamber 29 is completely‘sealed:from the
`“exteriorof the housing means 26;
`Since the chamber 29 of the device 30:is‘at:atmo-
`spheric condition, it can be seen that as the pressure
`fluid is being charged into the chamber 29, the result-
`ing pressure differential acting across the walls 31 and
`32 of the device 30 causes the walls 31 and 32 to col-"’
`lapse toward each otheras illustrated in FIG. 4 and
`have the flutes 35 thereof intimately fit within each
`other so that both walls 31 and 32:are pushing toward
`each other with the same force. Thus, neither wall 31
`or 32 is overstressed by the charged pressure fluid ”
`within the chamber 29 and therefore will not take any
`adverse permanentsetfrom the fluid pressure charge in
`the chamber 29 even though the charged device 25
`may remain in a stored and precharged condition for a
`relatively long period of time before the sameis utilized ©
`with the container means 22 forr the air bag safety sys-
`tem 20.
`The precharged sensing means$25 of this invention is
`adapted to be disposed within the main chamber 52 of
`the container means 22 in the mannerillustrated in
`FIG. 6 and can be supported therein: by suitable
`bracket means 53. The terminal rod 45 of the device 25
`could be electrically interconnected by a lead 54 to a
`
`‘exists:such |as by ‘flashing a light, sounding,aran alarm,
`25:ete.
`« After the precharged device 25.ofthis invention is
`assembled iin the chamber’52 ofthe container means 22
`“in the mannerillustrated in FIG.6; the chamber 52.of
`. the container means 22:oan be charged: withits pressur-
`‘ized fluid througha filling tube:67, FIG.6, to the prede-
`termined ‘pressure level :thereof..When the -pressure
`level within the chamber 52:reaches. substantially the
`“Same: pressure level as: within the.chambér 29of. the
`w in ‘sensing‘device 30 ofthé sensing means,25; the chamber
`36of the:device 30:-within thé:chamber 29 of the-hous-
`ing means 26 is nowreceiving pressure fluid thatis.in
`the chamber 52:of: the. container means.:22-and. has
`‘causedthepressure differéntial across-the-walls 31. and
`:'32 ofthe device'30to decrease. so that when-the.cham-
`‘ber 52:is charged to.a pressure level-only slightly aboye
`the pressure level in thechamber 29 of the sensing
`device 25, the movable wall 31 is moved by the pres-
`sure:differential acrossthe:same in such a mannerthat
`“theflat part 43:thereof makes electrical contact: with
`"45.
`the end surface 44 ofthe terminal rod 45.in the manner
`« illustrated in FIG:5 to:therebyeffectively complete the
`“-electtical circuit through :the .indicator 24..Thus, the
`indicator 24 will indicate that the container means 22is
`charged to the proper pressurelevel and that as long as
`the pressure in the chamber52 of the container means
`22 remains at such pressure level and does not fall
`below the same by approximately 200 psi or other
`pre-selected amount, the indicator 24 will have the
`electrical circuit completed therethrough by the sens-
`ing means 25 in a mannerillustrated in FIG. 5. Thus,
`the fill tube 67 can be sealed closed by the sealing
`means68illustrated in FIG. 6 and the container means
`22 can now beutilized in the vehicular air bag safety
`system 20 of FIG. 1.
`When the charged container means 22 is utilized in
`the vehicular air bag safety system 20 as illustrated in
`FIG. 1, the indicator 24 will continuously indicate that
`the pressure level within the container means 22 is at
`the proper pressure level for safe operation of the air
`bag 21,
`However, should the pressure within the chamber 52
`of the container means 22 fall approximately 200 psi
`below the initial charge value thereof, the resulting
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`pressure differential acting across the wall: 31-ofthe
`device 30 ‘of the sensing means-25will cause the wall 31
`to have the central part 43 thereof move away from the
`end 44 of the terminal rod 45 and thereby break the
`electrical circuit therebetween and, thus, break: the ”
`electrical circuit through the indicator 24 so that the
`indicator 24 will provide its warning function to the
`operator of the vehicle that the container means 22 for
`the ‘air bag safety means 20 is.in a damaged condition
`so that the same will not operate the air bag 21 in the
`proper manner and. must be immediately checked.
`If desired, the terminal 57 can be. eliminated and the
`side 64 of the power source could be connected to
`ground while the housing part 28 of the sensing means
`25 could be formed of conductive material .and..be™
`effectively interconnected to ground through ’ the
`bracket.53 and container means 22. Thus, in order for
`an electrical circuit to.be completed through the indi-
`cator 24, the wall 31 of the device 30 must. make
`contact with the terminal rod 45.
`bat
`Therefore, it can be seen that this invention. provides
`an improvedfluid operated pressure sensing meansthat
`can have thefluid thereof precharged therein and such
`precharging of the pressure fluid therein will not cause
`the movable wall means thereof to take an adverse
`permanentset, the pressure sensing meansofthis in-
`vention being adapted to be disposed within a main
`container means that is to be subsequently pressurized
`so that the same will be temperature compensated by
`the fluid pressure within the main container meansfor
`‘the reasons fully set.forth in the aforementioned co-
`pending patent application.
`:
`It can also: be seen that this invention provides a
`method for making such afluid operated sensing means
`as well’as an improved pressurized container means
`and method of making the same. ©.
`oe,
`While the. form and method of the invention now
`preferred have been disclosed and described as .re-
`quired by PatentStatutes, it is to be understood that
`other forms and methods canbeutilized andstill come
`within the scope of the appendedclaims. -
`:
`‘Whatis claimedis: -
`a”
`co
`1. In combination, a container means having a pres-
`surized fluid therein, and fluid operated sensing means
`‘ carried by said container means for sensing pressure
`changes within said container means,’ said sensing
`meansand said container means being so constructed
`
`“8
`and. arranged thatsaid sensing meatis is temperature
`compensated by being disposed within said container
`means to be substantially surrounded by a reference
`. pressure’ of said fluid-of said container meansso that
`‘pressure changes of said fluid insaid container means
`caused bytemperaturechanges thereofare ineffective
`to cause sensing thereof by said sensing meansas the
`‘fluid of said sensing meansis at the same temperature
`as said fluid in said container méans, said fluid operated
`sensing means‘and said container means having been
`initially charged with their respective pressurized fluids
`to substantially the same pressure levels, said sensing
`means comprising: a housing means secured in said
`conitainerand. having a chambertherein, a double wall
`fluid operated device disposed in said chamber of said
`_ housing means and being carried by the same, said
`walls of said device defining a.chamber therebetween,
`said device having passage meansinterconnecting said
`-chambez' of said device to the exteriorof said housing
`means so ‘as to be in fluid communication with said
`fluid in said container meanis, and a charge of pressure
`fluid sealed in-said chamberof said housing means to
`provide said pressurized fluid of said sensing means,
`said charge of fluid in said chamber of said housing
`meansbeing‘adapted to holdsaid walls of said device in
`intimate contact with each other throughoutthe entire
`" effective surface areas thereofso that the samewill not.
`take a permanent set when the chamber therebetween
`is at atmospheric conditions.
`. 2. A combination as set forthin claim 1 wherein a
`contactmeansis carried by said housing means andis
`_ disposed within said chamberof said housing means,
`said device and said contact means being so con-
`structed and arranged that one of said walls makes
`contactwith said contact meansas long as the pressure
`value of the’ fluid in. said chamber of said device ‘is
`substantially the. sameasthe pressure valueofthefluid
`sealed in said chamberof said housing means. _
`3. A.combination as set forth in-claim 2 wherein said
`contact means comprises a terminal rod insulated from
`said housing meansand having one endthereof dis-
`_posed in said chamberto be contacted by saidone wall
`of said device.and having the other end thereofproject-
`ing out of said housing means for exterior lead attach-
`mentthereto.
`_.
`:
`ec en
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`Page 6 of 6
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`KSS 1028
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