Inner Container Support Structure For Dewar Vessel

Abstract

A dewar container has one end of a bellows supported above the outer wall and the other end connected to a closure plate affixed to the top of the inner container's neck tube so that the inner storage container is pendularly suspended from the outer wall by the neck tube and bellows. A cylindrical support surrounds the bellows and extends downwardly from the closure plate to a support adapter on the outer wall. The cylindrical support is free to move up and down with respect to the outer wall's support adapter as the inner container undergoes its pendular motion, but a tab and slot arrangement prevents more than a predetermined amount of both upward and rotational motion of the support with respect to the outer wall, while engagement of the support with the adapter limits downward motion of the inner container with respect to the dewar's outer wall. The inner containers of dewar vessels are frequently supported within the vessel's outer walls by means of a relatively long neck tube affixed to the inner container. In order to prevent undue heat leak from the dewar's surroundings into the container interior through the neck tube, however, the neck tubes are frequently made of a thin low heat conductive material. But because of the thin neck tube walls, it has been necessary to provide auxiliary supports to prevent the type of relative motion between the inner container and the dewar's outer wall that would damage the neck tube. Alternatively, if it is desired to eliminate auxiliary supports between the inner container and the outer walls, it has been necessary to make the vessle's neck tube sufficiently strong to withstand both the tension and bending stresses to which the neck tube is subjected as well as torsional stresses which occur from time to time. This type of solution, however, has resulted in an increase in the overall heat conductivity of the thusly strengthened neck tubes. One solution to the above problems has been to suspend the neck tube and thereby the inner container from the outer wall by a bellows arrangement. In this manner, a certain amount of flexibility has been provided between the vessel's outer and inner walls so as to permit the vessel's neck to be somewhat thinner. In thusly structured devices, however, the combined load of the fluid in the inner container and the forces due to the space between the vessel's walls having been evacuated, has compressed the bellows to the point where it is not sufficiently flexible to accomplish its intended purpose. Similarly, a bellows that is made sufficiently strong to avoid such loads is not sufficiently flexible to begin with. Consequently, it is an object of this invention to provide a support structure for the inner container of a dewar vessel wherein the inner container is pendularly suspended within the vessel's outer walls by a flexible bellows, but wherein the bellows is not required to be so heavy as to either lose its intended flexibility or be so thin that it will be compressed to the point where it loses its flexibility. An additional drawback of the previous types of bellows suspension systems is that the bellows are not well suited for withstanding torsional loads caused by relative rotation between the vessel's inner and outer walls. Consequently, it is another object of this invention to provide a flexible bellows suspension system for a dewar's inner container wherein the bellows is substantially isolated from torsional loads. In accordance with the principles of the invention a bellows is connected between the top of the inner container's neck tube and the vessel's outer walls so that the inner storage container is pendularly suspended and adapted for both pendular and vertical axial motion with respect to the dewar's outer walls. A motion limiting compression support is affixed to the top of the neck tube. This member is adapted to move upwardly a predetermined amount but, engages a support adapter on the dewar's outer wall after the bellows is contracted to the point where the inner container undergoes a certain predetermined amount of downward motion relative to the vessel's outer wall. In this manner, the inner container and the neck tube are permitted to undergo pendular motion without the neck tube being subjected to bending stresses so that the neck tube can be made thinner than otherwise required. In addition, a tab is either located on the outer wall's support adapter so as to engage a slot in the compression support; or the tab is located on the compression support so as to engage a slotted element on the vessels outer wall. In either case, the tab and slot structure prevents the bellows from being subjected to torsional stresses so that the bellows can be made thinner and thereby more flexible. The foregoing and other objects, features, and advantages of the invention will be apparent from the more particular description of preferred embodiments thereof, as illustrated in the accompanying drawings, wherein the same reference numerals refer to the same parts throughout the various views. The drawings are not necessarily intended to be to scale, but rather are presented so as to illustrate the principles of the invention in clear form.

Description

In the drawings:

FIG. 1 is a pictorial view of a dewar vessel of the type in which this invention finds particular utility and illustrates one embodiment of the invention's means for limiting the torsional stresses that are transmitted to the bellows;

FIG. 2 is a fragmentary sectional view taken along the arc 2--2 in FIG. 1;

FIG. 3 is a pictorial view of the neck of a dewar vessel employing an alternative embodiment of the tab means for preventing torsional stresses from being transmitted to the bellows;

In FIGS. 1 and 2, a conventional dewar vessel 10 has an outer wall 12 spaced from an inner container wall 14 by a vacuum space 16.

The vacuum space preferably contains one or another of a variety of bulk insulation materials such as a laminated insulation or suitable opacified powder. These matters, however, form no part of the instant invention and will not be further discussed.

The inner container 14 is supported from the outer container 12 by means of a low thermal conductivity neck tube 18 which is preferably made of a fiberglass reinforced expoxy resin or stainless steel and should have as thin a wall as possible compatible with the strength required to support the inner container 14 and its contents.

A support adapter or collar 20 is welded or otherwise suitably connected in a gas tight manner to an extension 22 of the vessel's outer wall 12. Similarly, an upper collar or closure plate 24 is affixed at 26 by means of a gas tight seal about the outer circumference of the low conductivity neck tube 18; and a flexible bellows 28 is connected between flange 30 on the lower collar 20 and flange 32 on the upper collar 24. In this manner, the inner container 14 is pendularly suspended from the dewar's outer wall 12 by means of the flexible bellows 28 so that the inner container is free to undergo motion within the vacuum space 16.

A cylindrical support 36 is welded at 38 to the outer circumference of the upper collar 24 which also functions as a closure plate for the vacuum space 16. The cylindrical support has a plurality of vertical slots 40 about its circumference and extends downwardly about the bellows 28 so as to be slidably disposed about a shoulder 42 on the outer wall's support adapter 20. The cylindrical support, therefore, is permitted to move upwardly or pivot back and forth about its lower outside rim 44 as it follows motion of the upper collar 24 which moves with the pendular or vertical motion of the inner container. When the inner container moves a predetermined distance downwardly with respect to the outer wall 12, however, the lower surfaces 46 of the cylindrical support bear against the shoulder 42 of the outer wall's support adapter 20 so as to rigidify the connection between the vessel's inner and outer walls. In this manner, the bellows 28 is permitted to have its walls desirably thin so as to be sufficiently flexible when the neck tube 18 is normally loaded, but both the bellows 28 and the neck tube 18 are supported by the cylindrical support 36 when the neck tube is subjected to high loads.

In the FIG. 1 and 2 embodiments, a plurality of bent tabs or pins 50 have their lower portions 52 welded to the outer circumference of the support adapter 20, while their other ends 54 extend inwardly through the vertical slots 40 on the cylindrical support 36. This structure permits the cylindrical support to move upwardly or pivot until the lower surface 56 of one of the vertical slots 40 is brought into engagement with the lower surface 58 of the corresponding tab 50. This structure, therefore, functions to limit the upward motion of the inner storage container with respect to the outer walls.

In addition, rotational motion of the clindrical support, and thereby the inner container, is limited by one of the sides 60 of one of the tabs 50 with a corresponding side 62 of one of the vertical slots 40. Consequently, although the structure permits a predetermined small amount of rotation to be transmitted to the flexible bellows 28, the bellows is thusly isolated from large torsional stresses of the type which would otherwise require a substantially stronger bellows and neck structure.

The FIG. 3 embodiment of the invention is substantially the same as that illustrated in FIGS. 1 and 2 except that a plurality of tabs 70 and slotted stanchions 72 are substituted for the first embodiment's combination of tabs 50 and slots 40. In the FIG. 3 embodiment, the tabs 70 are affixed to the cylindrical support 36 and extend outwardly into slots 74 of the stanchions 70 which are affixed at their lower ends 76 to the dewar's outer wall 12. In this manner, the upward motion of the support cylinder 36 is limited by engagement of one of the upper surfaces 78 with the inner top portion 80 of a corresponding stanchion; and rotary motion of the cylindrical support 36 is limited by engagement of a side 82 of one of the tabs 70 with one of the inside surfaces 82 of one of the stanchions 72. In all other respects, the second embodiment's structure is substantially equivalent to that of the first, and, hence, will not be further discussed. Those skilled in the art, however, will appreciate that both embodiments provide a structure whereby the inner container can be pendularly suspended without requiring either an undesirably rigidified bellows or an overly thick neck tube. Similarly, it will be appreciated that both embodiments prevent substantial torsional stresses from being transmitted to the bellows.

While the invention has been particularly shown and described with reference to preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and detail may be made therein without departing from the spirit and scope of the invention. For example, although the invention has been described in connection with a dewar having a cylindrical neck, it will be appreciated that the invention is equally applicable to dewars having square necks or, in its broader aspects, to vessels having the storage container's support structure located substantially within the vessel's outer walls rather than extending outwardly therefrom as has been illustrated.

Claims

The embodiments of the invention in which an exclusive property or privilege are claimed are defined as follows:

1. A neck suspension for a vacuum insulated double walled storage vessel having an inner storage container thereof suspended from an outer wall by a low thermal-conductivity neck tube, the suspension for said neck tube comprising:

a bellows affixed to said outer wall;

connecting means for connecting said bellows to said neck tube so that said inner storage container is pendularly suspended from said outer wall by said neck tube and bellows, and adapted for pendular and vertical axial motion with respect to said outer wall;

limit means spaced apart from said inner storage container and disposed externally of said bellows for limiting both upward and downward vertical motion of said inner container with respect to said outer wall to a predetermined amount; and

additional rotation limiting means disposed externally of said connecting means to limit rotational motion of said inner storage container with respect to said outer wall.

2. A neck suspension for a double walled storage vessel having an inner storage container thereof suspended from an outer wall by a low thermal-conductivity neck tube, the suspension for said neck tube comprising:

a bellows affixed to said outer wall;

connecting means for connecting said bellows to said neck tube so that said inner storage container is pendularly suspended from said outer wall by said neck tube and bellows, and adapted for pendular and vertical axial motion with respect to said outer wall;

limit means for limiting both upward and downward vertical motion of said inner container with respect to said outer wall to a predetermined amount; and

wherein said limit means includes a support affixed to said connecting means and extending toward said outer wall, but movable with respect to said outer wall from an upper position to a lower position when said support is in contact with said outer wall whereby said inner container has a predetermined minimum lower position with respect to the outer wall.

3. The apparatus of claim 2 including a rotation limiting means for limiting rotational motion of said inner storage container with respect to said outer wall.

4. The apparatus of claim 2 including an upper motion limiting means operative in combination with said support means to limit upward motion of said inner storage container with respect to said outer wall.

5. The apparatus of claim 4 including a rotation limiting means for limiting rotation of said inner storage container with respect to said outer wall.

6. The apparatus of claim 4 wherein said upper motion limiting means is affixed to said outer wall and engageable with said support when said support is in a predetermined upper position.

7. The apparatus of claim 6 including a rotation limiting means for limiting rotation of said inner storage container with respect to said outer wall.

8. The apparatus of claim 6 wherein said support has a slot therein said upper motion limiting means having an end thereof extending into said slot so as to limit upward motion of said support by engagement of said end with the lower end of said slot and to limit rotational motion of said support and thereby said inner container by engagement of a side of said limiting means with a side of said slot.

9. The apparatus of claim 6 wherein said means for limiting upward motion of said support includes a slotted means affixed to said outer wall and a means affixed to said support and extending therefrom into the slot on said slotted means whereby upward motion of said support is limited by engagement of said means extending therefrom with said slot; and rotational motion of said support is limited by engagement of the sides of said extended means with the sides of the slot.

10. A neck suspension for a double walled storage vessel having an inner storage container thereof suspended from an outer wall by a low thermal conductivity neck tube, the suspension for said neck tube comprising:

a first collar affixed to the top of said neck tube and extending outwardly therefrom;

a second collar affixed to said outer wall;

a bellows connected between said first collar and said second collar so that said neck tube and thereby said inner container are pendularly suspended within said outer wall by means of said flexible bellows;

a support member surrounding said bellows and affixed at an upper end to said first collar and extending downwardly toward said second collar, said support member being adapted to move upwardly and downwardly with said inner container, but limited in its downward motion by engagement with said second collar so as to correspondingly limit downward motion of said inner container with respect to said outer wall.

11. The apparatus of claim 10 including an outwardly projecting arm on said support member; and a slotted stanchion affixed to said outer wall, said arm extending into said slotted stanchion so as to have an upper surface thereof engageable with said slotted stanchion upon a predetermined amount of upward motion of said inner storage container with respect to said outer wall, and a side surface thereof engageable with a side of said slotted stanchion upon more than a predetermined amount of rotation of said inner storage container with respect to said outer wall.

12. The apparatus of claim 10 an including an inwardly projecting arm affixed to said outer wall; and a slot in said support member, said arm extending into said slot and engageable with a lower portion of said slot upon a predetermined amount of upward motion of said inner storage container with respect to said outer wall, and engageable with a side portion of said slot upon a predetermined amount of rotation of said inner storage container with respect to said outer wall.