US2941403A - Liquid depth gauge - Google Patents

Description

June 21, 1960 J. STEENFELD ETAL 2,94l,403

LIQUID DEPTH GAUGE Filed April 29, 1955 a U r////////// INVENTORS JOSEPH STEENFELD 4 GEORGE K Zro W A OR Y United States Parent O LIQUID DEPTH GAUGE Joseph Steenfeld, North Arlington, and 'George V. Zito,

Northvale, NJ., assignor to Bendix Aviation Corporation, Teterboro, NJ., a corporation of New Jersey Filed Apr. 29, 1955, Ser. No. 504,836

7 Claims. (CI. 73-304) This invention relates to liquefied gas converters, in which a supply of liquefied gas is maintained in a container, from which gas evaporated from the liquid is withdrawn as needed. Systems of this kind are used to supply oxygen to high-flying aviators.

Apparatus of this type must be provided with -arrangements for introducing liquid to replenish the supply when required, and should include means for indicating the amount of liquid in the container. This is efiectively accomplished by an electrical system including a Wheatstone bridge having in one arm a condenser immersed in the liquid and extending vertically throughout the liquid depthrange, an oscillator circuit for energizng the bridge and a bridge output circuit containing anindi cator actuated by variations in the capacity of the mmersed condenser due to changes in liquid level. The indicator may be located at a point remote -from the container, which is provided with a transmitter unit including the immersed condenser, and preferably the other bridge elements and the oscillator circuit. The unit must be associated with, and advantageously is removably mounted on, the container, which is designed to provide insulation for the low temperature liquid, frequently being constructed with insulated inner and outer walls and a long neck to minimize the heat transfer by conduction.

An object of the invention is to provide a novel arrangement for insert ing and supporting an immersion condenser in a container.

Another object is to provide an arrangement of this type that is suitable for use with a container having an elongated neck. I

A purpose is `to provide a novel arrangement for introducing liquid and withdrawing gas from the container. A related purpose is to provide such an arrangement in combination with an immersion condenser.

An object is to provide a unitary combination structure functioning both as an immersion condenser and as liquid introduction and gas withdrawal means.

Another object is to provide a unitary fitting, removably mountable in the container mouth and carrying as a unit an immersion condenser, a liquid supply and gas removal system, Components of an electrical circuit responsive to liquid depth, or any combination of these features.

A particular object is to provide an improved immerson condenser Construction, and especially one that is readily produced from standard material and -s Conveniently and rapidly assembled, while maintaining high electrical eflicieney and responsiveness to liquid level changes.

A further purpose is to provide an mmersion condenser with simple and eificient radio frequency shielding suitable for efiicient operation when the condenser is energized -by a local oscillator circui-t. A related purpose is to provide such shielding in a simple, eflicient and rugged unitary construction.

Another object is to provide improved anangements for gas withdrawal from gas space above a submerged con denser unit.

The foregoing and other objects, purposes and advantages of the nvention will appear more fully from consideraton of the detailed description which follows, in conjuncton with the accompanying drawing wherein one embodiment of the invention is illustrated. It is to be expressly understood, however, that the drawing is for the purposes of illustration and description, and is not to be construed as'defining the limits of the invention.

In the drawing:

Fig. '1 is a somewhat diagrammatic vertical central section through an oxygen Converter system embodying the invention, with parts shown in perspective and broken away; and

Fig. 2 is an enlarged longitudinal central section through the lower portion of the immersion condenser probe.

The invention is illust'ated in its application to an oxygen converter system which includes an insulated liquid oxygen' container or 'bottle 10 having a body 11 and a neck 12,' both comprised of an inner Wall 13 and an outer wall 14 with an insulating space 15, normally evacuated, between them. Walls 13 and 14 are sealed at the upper end of neck 12'to a metal cap -16 having a central mouth or'opening 17. Insulated bottles of this type are known, and features thereof which Would normally be included in practice have been omitted from this showing for purposes of Simplicity, since they have no relationship to the invention.

A fitting 18 of electrically conducting metal is mounted in the bottle mouth 17, as by threading neck 19 into said mouth so as to seal the bottle 10. An immersion condenser assem bly 20 'is mounted in neck 19 and extends downwardly through the bottle neck 12 substantially to thebottom of the bottle 10, this type of assembly being generally referred to as a probe. It includes a condenser unit formed of plates insulated from each other and extendng from substantially the bottom of the bottle 10 to a point above the maximum level 21.

The condenser unit forming part of assembly 20 may -advantageously terminate substantially `below the fitting neck 19, and of course above the maximum liquid level, as shownin the form illustrated. In this form the condenser unit of probe 20, shown in detail in Fig. 2, includes an inner tubular condenser element 22, a-n intermediate tubular insulated condenser element 23 and an external tubular condenser element 24, all concent rically arranged,

. and Conveniently cylindrical as in the illustrated embodiment.

The intermediate element 23 is supported and insulated by rings 25 of insulating material fitted around the inner eylinder 22 andbear ing against shoulders 26 on said cylinder Rings 25 are advantageously L-shaped in crosssection, andinclude a cylindrcal body portion 27 fitting against the inner face of intermediate eylinder 23, and a r adially extendingflange 28 fitting the inner surface of outer' eylinder 24, and hearing against the adjacent end of the intermediate eylinder 23. Abutting against the axially outerfaces of insulation ings 25 are annular metal retaining caps 29 fi-tting tightly around inner; eylinder 22 and connected thereto as by soldering. Outer eylinder 24 fits snugly around caps 29 at its ends, and is suitably engagedtosaid caps, as by spinning the ends 30 of eylinder 24 around the adjacent margins of said caps'.

condenser 'assembly. 20 is provided with, openings through which liquid will pass into the spaces 31, 32 jon either side ofintermediate eylinder 23 and promptly as sume the same levelas the liquid outside of said assembly.

with one 'or more openings 33; immediately ;adjacent` to= the bottom levels of said spaces 31, 32, and intermediate height of the liquid cylinder 23 is likewise -provided with one or more openings 34 at substantially the same level. The arrangement is such that by properly positioning and proportioning the lower cap 29 and adjacent insulation ring 25, liquid at a very low level in bottle' will enter the condenser arrangement and register on the indicating system.

Similar openings 35 in inner cylinder 22 and openings 36 in intermediate cylinder 23 are provided immediately adjacent to the upper ends of spaces 31, 32, and are located above the maximum height of liquid level 21.

The assembly or probe 20' includes an arrangement for suspending the condenser unit above described and for providing a connection between the passage 37 within the inner cylinder 22. In the construction shown, the latter cylinder is extended through fitting neck 19 into fitting 18, and is attached thereto, as by soldering said cylinder 22 to an anrular supporting fiange 38. The open upper end of passage 37 communicates with a liquid inlet passage 39 extending outwardly through a radial arm 40 of said fitting, and advantageously threaded at its outer end to receive a liquid supply pipe 41.

The space 4-2 in bottle 10 above liquid level 21 is filled with gas, which in the case of an oxygen supply system consists of gaseous oxygen evaporated from the liquid in the lower part of the bottle. An arrangement is pro vided for Withdrawing gas from space 42 as desired. For this purpose the fitting neck '19 is provided with an axial bore larger in diameter than the inner cylinder 22, which passes through and is spaced from the Walls of said bore to provide an annular passage 43 communicating with a gas outlet passage 44 extending through radial arm 45 of fitting 18, and advantageously threaded at its outer endto receive the gas discharge pipe 46. The radial arms 40 and 45 may conveniently be located opposite each other, With axially aligned outer openings, and passages 39 and 44 are preferably arranged with passage 49 sloping upwardly to the inlet of passage 37, while passage 44 slopes downwardly to a point below said inlet, flange 38 and the upper end of inner cylinder 22.

It will be understood that the liquid oxygen supply arrangement and the gas discharge arrangement will normally be provided With numerous features such as valves and Controls, which are not relevant to this invention and therefore have been omitted in the interests of simplicity.

The probe 20 is advantageously provided with gas withdrawal means. cylindrical casing 47 fitting within and attached to the outer wall of the outlet passage 43 in neck 19', as by soldering, and extending downwardly to the upper end of outer cylinder 24. Casing 47 and inner cylinder 22 are spaced to form an annular gas passage 48 communicating with passages 43 and 44, and provided with suitable gas inlet means such as openings 49 in said casing, advantageously near .the lower part thereof adjacent to the upper end of outer cylinder 24.

Casing 47 is preferably fixed to cylinder 24 to provide added support and rigidity, being axially aligned with said cylinder in the llustrated embodiment, abutting the upper end of the latter cylinder and attached thereto as 'by a cylindrcal connecting collaa' 50 fitting against the outer faces of casing 47 and cylinder 22 and firmly attached to said casing and cylinder as by soldering. As already indicated the condenser unit forming the lower portion of probe 20 is ,electrically connected to a crcuit responsive to variations in the capacity of said condenser caused by changes in the liquid level. A oircuit of this type is shown, for instance, in application Serial No. 498, 6 81, filed April l, 1955, by George V. Zito. Components of such a circuit, advantageously including all elements thereof except the indicator unit, are enclosed in a cas-ing 51 mounted on fitting 18 and forming a compact unitary structure with the probe. As illustrated, said fitting is provided with a central positioning boss 52 to which the casing 51 is attached.

In the form shown this comprises a 2,941,4o3 i v An arrangement is provided for connect-ing the condenser unit formed by cylinders 22, 23 in said circuit. For this purpose electrically `connected cylinders 22 and 24 may be on the ground side of the circuit and in communication through fitting 18 with the ground side of the components in casing 51. An insulated lead 53 from said circuit is carried through aconnector 54 set in an insulating plug 55 into passage 37, the lower end of lead 53 passing through an opening 35 in the condenser portion of cylinder 22 and being electrically connected at 56 to the insulated intermediate cylinder 23. Casing 51 may be ,provided with the usual plug socket 57, through which leads to the remote indicator and source of electrical energy 'may be connected by 'a plug.

The probe 20 is arranged for convenient Construction, assembly and mounting on fitting 18, the probe being formed of metal cylinders of standard commercial type, With identical caps 29 and insulating rings 25, which may be sld into place `on the inner cylinder 22 and fixed in position engagng intermediate cylinder 23, after which the outer cylinder 24 may be fixed in place. The casing 47 with collar 50 can then be positioned and attached to cylinder 24. Likewise the casing 47 and inner cylinder 22 are arranged for convenient mounting in and attach ment to fitting 18. v

In operation, liquid oxygen is introduced through pipe 41 and passages 39 and 37, fiowing out of the bottom of inner cylinder 22 into the bottle 10 and through open- *ings 33 and'34 'into the space 31 and 32, Where the liquid level will be maintained at the same height as that in the bottle 10 and will suitably actuate the remote indicator. This makes it possible for the operator to regulate the supply of liquid oxygen by observing the indicator. Gas may be withdrawn as desired through pipe 46, passages 44, 43 and 48 and inlet openings 49, being replaced by evaporation from the liquid.

It will be evident that with this arrangement the entire liquid supply and gas discharge system is carried by the fitting '18, which -also carries the condenser assembly or probe 20 and the electrical circuit elements in casing '51. This entire assembly may be inserted in or removed 'from a -bottle 10 by simply screwing the neck 19 in or out of the bottle mouth 17.

It is also pointed out that the invention is eifective for'shielding the condenser elements and leads carrying radio f-requency voltages. The outer and inner tubular condenser elements 22 and 24 are conductively connected to the fitting 18 and the frame of the circuit oasing '51 which form one side of the circuit connected to :a reference voltage, usually ground; and the lead 53 from the insulated intermediate plate 23 passes upward to the circuit elements in casing 51 through inner tubular element 47 and fitting 18, providing continuous shielding.

,Although but one embodiment of the invention hasbeen illustrated and described in detail, it is to be expressly understood that the invention is not limited thereto. Various changes can be made in the design `and arrangement of the parts without departing from the spirit and scope of the invention, as the same Will now be understood by those skilled in the art. For instance, the upper' part of the inner cylinder 22 functions as 'a support for the condenser unit while the lower part operates as an element of said unit; and while these parts are shown as integral, this arrangement is not intended to be re- -strictive Likewise, while the casing 47 in the form illustrated is fixed to the condenser unit and acts as a support, 'being connected to the interier of the container 10 to openings 49, the invention is not limited to the use of this casing nor its equivalent as a support, or 'to the particular type of gas inlet illustrated.

We claim:

1. A liquid level sensing system for use with a liquid container having `a top opening, comprising a fitting `for said opening, a tubular metal support element mounted on said fittng and extending downwardly from the fittng, a coaxial tubular condenser unit carried by said support element and having an open passageway communicating with the interier of said tubular element, and a fluid passageway in the fittng communicating with the interier of said tubular element, arranged for the passage of fluid through said fittng and support element.

2. A liquid level sensing system for use with a liquid container having a top opening, comprising a fittng for said opening, -a tubular metal support element mounted on said fittng and extending downwardly from the fittng, a -tubular metal condenser element mounted concentrically on the lower part of and insulated from said support element, arranged for forming with the lower part of the support element and immerson condenser unit, and a fluid passageway in the fittng communicating with the interier of said tubular support element, arranged for the passage of fluid through said fittng and support element.

3. A liquid level sensing system for use With a liquid container having :a top opening, comprising a fittng for said opening, a tubular metal support element mounted on said fittng and extending downwardly therefrom, a coaxial tubular metal condenser unit carried by said support element and having an open passageway communicating with the interier of said tubular element, and a fluid passageway in the fittng communicating with the interier of said tubular element, said fittng being provided with a second separate fluid passageway communicating with the upper part of the centainer.

4. A liquid level sensing system for use with a liquid container having a top opening substantially above the liquid level in the container, comprising a fittng for said opening, an inner hollow metal cylinder mounted on the fittng and extending downwardly therefrem, arranged to extend through said opening into the container below said liquid level, a liquid passageway through the fittng communicating with the interier of said cylinder, and an outer metal cylinder mounted on the fittng concentric with and spaced from the inner cylinder below the fittng, and including an opening :for gas in the upper part contiguous to the fittng, said fittng including a gas passageway communicating with the space between said cylinders.

5. A liquid level sensing system including a liquid centainer having a top opening, a fittng mounted in said opening, a liquid level sensing condenser mounted on the fittng and extending downwardly into the container, including a tubular condenser comprsing two concentric plates located in the container, a liquid supply passage in the fittng in communication with the interier of said tubular condenser, and a gas passage in s-aidvfitting in communication with the upper part of the centainer.

6. A liquid level sensing 'system including a liquid container having a top opening, a fittng mounted in said opening and provided with a passage, a first tubular metal condenser plate mounted on the fittng in communication with said passage and extending downwardly therefrom into the container, a second associated tubular condenser plate concentrc with said first plate, and means for mounting the second plate in `capacitve relation to and insulated from the first plate, said fittng including a second passage connected to an opening in the lower part of the fittng arranged to communicate with the upper part of the centainer.

7. A liquid level sensing probe for use with a liquid container having a top opening, comprising a fittng for said opening provided with a passage, a first 'tubular metal condenser plate mounted on the fittng :in communication with said pass-age and extending downwardly firom the fittng, a second -associated tubular metal condenser plate concentric with said first plate and spaced from the fittng, and means for supporting the second plate from the fittng, said fittng being provided with a second passage having an opening in the lower face of the fittng, ar'anged for communication with the upper part of the centainer.

References Cited in the file of this patent UNITED STATES PATENTS 2,127,875 Lippert Aug. 23, 1938 2,377,275 Smith May 29, 1945 2,563,280 Shaefer Aug. 7, 1951 2,754,457 Meyer July 10, 1956 FOREIGN PATENTS 455,731 Canada Apr. 5, 1949

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