US3370740A

US3370740A - Vacuum jacketed joint construction

Info

Publication number: US3370740A
Application number: US475354A
Authority: US
Inventors: James H Anderson
Original assignee: Individual
Current assignee: Individual
Priority date: 1965-07-28
Filing date: 1965-07-28
Publication date: 1968-02-27
Anticipated expiration: 1985-02-27

Description

Feb. 27, 1968 .1. H. ANDERSON 3,370,740

VACUUM JACKETED JOINT CONSTRUCTION Filed July 28, 1965 4 Sheets-Sheet 2 /2c /ac 7 ATTORNEY5 ZMAM, A /JWAM Feb. 27, 1968 J. H. ANDERSON 3,370,740

VACUUM JACKETED JOINT CONSTRUCTION Filed July 28, 1965 4 Sheets-Sheet s /wA hg w/wzm ATTORNEKS' Feb. 27, 1968 J. H. ANDERSON VACUUM JACKETED JOINT CONSTRUCTION Filed July 28, 1965 4 Sheets-Sheet 4 7M ATTORNEYS United States Patent T 3,370,746 VAUUM .iACKETEl) JGINT CONSTRUCTIGN James H. Anderson, 1615 Hillock Lane, York, Pa. 17403 Filed July 23, 1965, Ser. No. 475,354 13 Claims. (Cl. Zia-15) ABSTRACT (9F THE DISCLGSURE A double-walled thermally insulating, evacuated panel has an internal support arrangement which resists collapse of the walls by external forces acting on the walls. The support arrangement includes a series of post-like supports extending from the inner surfaces of the walls and tensioned cables passing in wave form over the free ends of the posts, thereby placing the latter in compres- SlOIl.

Disclosure This invention relates to thermally insulating walls for use in refrigeration systems or the like and in particular to double-wall constructions having an insulating vacuum between an inner wall and an outer wall.

More specifically, the invention is concerned with insulating wall structures which make effective use of the well-known principle of vacuum insulation and which at the same time have an internal supporting structure which resists collapse of the walls by atmospheric pressure and by an external load applied during use.

Any mechanical support structure extending across the evacuated space between walls inherently conducts some heat from one wall to the other by virtue of the necessary contact of the support structure with the walls. The principal object of the present invention is to provide an internal supporting structure in the vacuum space which will withstand external pressure forces while not materially reducing the effectiveness of the insulation. This is achieved, broadly, by means of a support having a minimum of contact with the walls, a small cross section through which heat is conducted and a long heat transfer path. In one preferred arrangement the internal support comprises a plurality of ribs or posts projecting transversely into the vacuum space from the inner surface of each wall and terminating short of the opposite wall, the ribs on one wall alternating with the ribs on the other wall. Cables under tension are strung over the inner edges of the ribs and are anchored at their ends so as to conveit external compressive forces acting on the external surfaces of the walls to compressive forces in the ribs and tension forces in the cables. In another preferred construction, the internal support includes tension cables which engage alternate corrugations on the inner and outer walls, the corrugations performing the same function as the previously described ribs.

It is a further object of the invention to provide prefabricated evacuated insulating panels embodying the improved internal supporting construction.

It is another object to provide panels as above described having edges constructed to be joined in overlapping relationship to other panels in a manner to reduce heat transmission at the junctions so that effectively insulated enclosures may be formed for storing or transporting refrigerated goods. The panels may be employed to form boxes having fiat or curved sides, rooms, refrigerator truck bodies, railway refrigerator car bodies and the like. The panels may form the walls of these structures or they may form a jacket to be applied to the exterior of existing structures.

It is a more specific object to provide a concentric double wall structure having the abovedescribed interior 3,37%,74fi Patented Feb. 27, 1968 support, the structure being suitable as an insulated cylindrical container or an insulated pipe line in which the interior support suspends the inner wall within the outer wall.

The invention will be further understood from the following detailed description in conjunction with the drawings in which:

FIGURE 1 is a perspective view of a simplified vacuum panel constructed according to the principles of the present invention;

FIGURES 2 and 3 are sectional views taken on the line 22 and 33 of FIGURE 1, respectively;

FIGURE 4 is a fragmentary sectional view illustrating one form of joint between adjacent panels in a common plane;

FIGURES 5, 6 and 7 are fragmentary sectional views illustrating modified forms of joints between adjacent panels in a common plane;

FIGURE 8 is a fragmentary horizontal sectional view illustrating a panel having a corner sectional integral therewith which is adapted to make a joint with another panel;

FIGURES 9 and 10 are fragmentary vertical sectional views of joints between a horizontal panel and a vertical panel;

FIGURE 11 is a top plan view of an open-top, closedbott-om container assembled from vacuum panels;

FIGURE 12 is a fragmentary horizontal sectional view on an enlarged scale showing a junction between two of the wall panels of FIGURE 11;

FIGURE 13 is a sectional view taken on the line 13-13 of FIGURE 11;

FIGURE 14 is a fragmentary transverse sectional view of a vertical panel having corrugated walls;

FIGURE 15 is a fragmentary transverse sectional view of a cylindrical container constructed in accordance with the principles of the present invention;

FIGURE 16 is a perspective view of a modified flat panel which is constructed to join with another panel along each edge;

FIGURE 17 is a schematic sectional view of a telescoping box construction having vacuum insulated walls constructed according to the invention; and

FIGURE 18 is a section view of a modified type of corrugated panel.

Referring to FIGURES 1-3 there is shown in simplified form a sealed vacuum panel A) which illustrates the principles of the present invention. As shown, the panel 10 is of rectangular profile having an inner wall 12, an outer wall 14, side walls 16 and 18 and end walls 20 and 22. In use the panel 10 may be employed as the side of a box or it may be joined end-to-end and side-to-side with other panels to form larger structures.

An internal support structure includes a plurality of rigid

rectangular plates

24, 26 and cables 28. The plates 24 are fixed along one edge to the inner surface of the inner wall 12 and are disposed in a plurality of rows which extend across the width of the panel. Each row contains a plurality of plates 24 disposed parallel to the end walls 20 and 22 in spaced apart relationship. The plates 25 are of similar shape and are bonded along one edge to the internal surface of the outer wall 14. The plates 26 are ali ned with and alternate with the plates 24 as seen in FIGURES 2 and 3, respectively.

The

plates

24 and 26 are slightly shorter than the internal thickness of the panel 10, and therefore their terminal edges do not contact the opposite wall. The cables 28 are disposed in planes parallel to the side walls 16 and 18 and are run in tension in a wave pattern over the terminal edges of the

plates

24, 26. One end of each cable 28 is fixed to the end wall 20 and the other end is 3 fixed to end wall 22. This arrangement insures that the vacuum load on the panel is carried by the

plates

24, 26 in compression and by the cables in tension. To effect this relationship it is necessary that the

plates

24, 26 project more than halfway across the vacuum space.

The

plates

24 and 26 and the cables 28 are preferably constructed of a strong material having low thermal conductivity. For example, the plates may be constructed of rigid plastic employed alone or reinforced with glass fibers, and the cables may be constructed of glass fiber, Nylon or Dacron.

It will be seen that the solid heat conduction path transversely through the panel is much longer than the thickness of the panel. Heat must fiow through the plate 24, down a section of cable 28 and then through the next plate 26 in order to pass from one wall of the panel to the other.

While the size and spacing of the panel walls and interior load bearing elements are not critical, it has been found that excellent insulation is achieved with panels having an inner thickness of 2 inches and plates which clear the opposite wall by A inch and which are spaced apart 3 inches.

Additional insulation is provided by installing a plurality of spaced apart radiation reflective shields 29'disposed parallel to the

walls

12 and 14 and extending between the

walls

16, 18, 20, 22. Preferably the shields 29 are thin sheets of plastic such as Mylar coated on both sides with a highly reflective thin metallic coating such as aluminum or gold. Preferably, also, the sheets are crinkled to provide substantially only point contact between them. If desired, substantially the entire space within the panel 10 may be filled with the sheets. The sheets may be cemented to one wall, or when crinkled and employed in large numbers, they may be held in place by the mechanical pressure of the supports and cables.

The cables 28 can be assembled over one wall assembly with the plates in place, with their ends anchored at any convenient place such as is shown at the end wall in FIGURE 3, or they could be anchored to one of the plates if so desired. An alternative anchoring spot is on the outer walls as shown in FIGURE 4. While various methods of assembly are possible a preferred one is to assemble one half of a panel with the cables 28 laid over the plates, and fastened at a measured length. Following this the other half or other wall with its plates in place and with crinkled insulation in place can be assembled over the cables, and clamped to the other wall to tighten the cables, following which the edges can be welded, brazed or otherwise secured. When a vacuum is drawn on the assembled panel through a suitable fitting (not shown) by a vacuum pump, the atmospheric pressure forces against both walls will hold the cables tightly in place.

If the panel is to be provided-with a transverse access opening therethrough as for instrument lines, this is desirably accomplished with the arrangement illustrated in FIGURE 3. The opening is defined by the bore of a tube 30 which passes through the inner and

outer walls

12 and 14 and which is sealed to the inner wall 12. An outer tube 32 surrounds that portion of the tube 30 which is outside the outer wall 14 and defines an evacuated annulus 34 which is in communication with the inside of the panel 10. The outer end of the annulus 34 is closed by a plate 36 which is sealed to both of the tubes 30 and 32.

In practice it will be desirable to construct the edges of the vacuum panel in a manner to lengthen the heat transmission through a joint formed by two abutting edges of ditferent panels. This may be accomplished in several diiferent ways as seen in FIGURES 4-10.

FIGURE 4 illustrates an edge-to-edge joint between two panels 10a disposed in a common plane. In this arrangement the end Wall 22a of one of the panels abuts the end Wall 20a of the other panel. The end Walls are inclined with respect to the inner and outer walls 12:: and 14a of the panels so as to increase the length of the heat transmission path between the latter at the location of the joint. Any suitable brackets (not shown) or bonding composition (not shown) may be employed to fasten the panels 10a together.

FIGURES 5, 6 and 7 illustrate joints in which the abutting end walls of coplanar panels are stepped in order to increase the heat transmission path. For simplicity the internal plates, cables and reflective shields have been omitted. In FIGURE 5 the end walls 20b and 22b of the panels 1012 are constructed in the form of a simple step. In FIGURE 6 the

end walls

290 and 22c of panels are constructed with an interlocking stepped configuration which prevents longitudinal separation of the panels after they have been joined. As shown, each end Wall has a projection and a cavity for mating with the other wall. FIGURE Tillustrates another interlocking stepped configuration to which the abutting end walls 20d and 22d are each provided with a plurality of alternate projections and cavities.

Referring again to FIGURE 6 there is also shown an additional construction for improving the insulation properties of a joint between panels. This additional construction is in the form of a vacuum jacket which overlies the joint. As shown, the jacket is formed by a channel member 38 and a cover plate 40 which is sealed between the flanges of the channel member 38 so as to form a vacuum space. Reflective shields 290 are provided within the space to improve its insulation. The jacket is placed over the joint with an insulating gasket 42 between the Web of the channel member 38 and the faces of the panels 10c and is secured in place with angle brackets 44. In the embodiment illustrated the jacket is relatively narrow and does not require internal support. A system of plates and cables may be employed if the width of the jacket is sufficiently great to require strengthening.

FIGURE 8 illustrates in horizontal section a vertical panel 10e having an integral corner section 46 which is at a right angle to the main section of the panel. In order to provide the necessary internal strength, the cable 28e is strung around the corner and anchored to the inner wall of the corner section 46. As shown, this is accomplished by mounting a support plate 48 in a diagonal position on the inner wall 122 at its junction with the inner wall of the corner section 46. In the embodiment illustrated the latter is constructed with a stepped configuraton so as to interlock with a fiat panel (not shown) in the manner shown in FIGURE 6. It will be understood that while the panel 10@ has been described as a vertical corner panel adapted for abutting with a vertical side panel, the same panel construction may be employed for a horizontal roof or floor panel for abutment with a vertical side panel.

FIGURE 9 illustrates in vertical section a vacuuminsulated joint between two panelsltlf, one of which is a horizontal roof panel and the other of which is a vertical side panel. As shown, the panels 10 have plain square edges like those of FIGURES 1-3, and the horizontal panel is rested on and secured to the upper edge of the vertical panel. The joint thus formed is also provided With an inner corner jacket 52 and an outer corner jacket 54, each of which is secured in place with angle brackets 56. The inner jacket 52 is constructed of an angle plate 58 contoured to mate with the inner walls 12 of the panels and a cover plate 60 sealed to the angle plate to define a triangular vacuum space. The outer jacket consists of an angle plate 62 contoured to mate with the outer walls 141 and a semi-cylindrical plate 64 sealed along its edges to the plate 62. Heat insulating

gaskets

66 and 68 are disposed between the jackets and the panels.

FIGURE 10 illustrates in vertical section view a joint between two panels 10g, one of which is a horizontal floor panel and the other of which is 'a vertical side panel. The end wall 20g of the vertical panel rests on the inner wall 12g of the horizontal panel and is offset inwardly from the end wall 18g of the latter. The external corner between the two panels is insulated with a gasket 70 and a vacuum jacket 72. The jacket 72 is of the same construction as the inner jacket 52 of FIGURE 9.

FIGURES l1, l2 and 13 illustrate the construction of an open-topped, closed-bottom refrigeration container 74 assembled from vacuum panels. As seen in top plan view in FIGURE 11, the container includes a floor panel 76 and four vertical side and corner panels 19]: of special stepped construction.

Referring to FIGURE 12 it will be seen that the joint between each two vertical panels 10h is formed by two overlapping tongues 78, 83 which are integral parts of the panels. The joint is held together by means of tension bolts 82 which extend parallel to the tongues between angle brackets 84 affixed to the external surface of the outer walls 14h. A compressible gasket 86 is disposed between the end of the outer tongue 39 and a cavity defined by the junction of the inner tongue 7 8 with the end wall 20h of the same panel. When the bolts 82 are drawn up, the gasket 86 becomes compressed, and most of the force is taken by the end of the inner tongue pressing against the end wall 22h of the other panel. The ends of both tongues are inclined so as to interlock the panels and to resist the tendency to pivot caused by the offset position of the bolts 82.

The arrangement relieves the abutting sides of the tongues 80 and 82 of a large proportion of the stress created by the bolts 82 and, accordingly, these sides 88 and 90 may be constructed of relatively low strength material and can be made thin to reduce heat conduction. Stainless steel is preferable because of its lower heat conductivity relative to steel.

It Will generally be desirable to provide inner support within the tongues 78 and 80 to resist the vacuum load. This may be accomplished by means of an auxiliary cable system, as seen within the outer tongue 80, or by means of a support beam, as seen within the inner tongue 78. The cable system is analogous to the main cable system (not shown) within the main section of the panels 10k and includes a row of vertically spaced support plates 92 bonded along one edge to the wall 88 and a corresponding number of tension cables 94 extending along the length of the tongue 80. The alternative construction, which is not as effective an insulator, consists of a foamed plastic beam 96 bonded to the wall 90 of the tongue 78.

FIGURE 13 shows the joint between the floor panel 76 and the side panels 10h of the container 74. The floor panel is square in plan view and has an upper wall 98 which is provided with an upstanding hollow flange 109 spaced inwardly of the edges of the panel. The lower edges of the side panels 1071 are disposed around the outside of the flange 1tl0 and are sealed thereto by a soft insulating gasket 102. The latter may be of flexible-lip or hollow construction both of which are conventional. If of hollow construction, it may be of the type which is inflatable with compressed gas. The actual construction of the gasket 102 is not critical so long as it makes a tight seal at the inner and outer edges of the joint and effects a long heat conductive path along the edges of the panels 10h.

The container 74 is readily disassembled into its component panels. Thus, it may be employed to transport refrigerated goods, disassembled at its destination and shipped back to its starting point for reuse.

FIGURE 14 illustrates in transverse section a vertical panel mi having corrugated inner and outer walls 121' and 14i which are disposed so that their peaks and valleys are directly opposite each other. The corrugated walls provide greater stiffness and bending strength than flat walls so that thinner material may be used for their construction. The space between the walls 122 and 1 1i carries horizontally spaced vertically extending ribs 241 and 26i which are analogous to the

plates

24 and 26 of FIGURES 1-3. Similarly, tension cables 28] are strung over the edges of the rims 241 and 261 to give increased load strength to the panel. Two adjacent panels of this construction may be joined by means of tension bolts 82i extending between suitable brackets 8 1ifixed to the outer walls 141 of the panels. The bolts 82i and brackets 84i are preferably recessed in one of the corrugations as shown so as to avoid unnecessary projections. This is of particular importance in trailer body construction where the maximum width of the body is set by law and in shipping box construction where the boxes must be stacked. In some constructions it may be desirable to employ a fiat outer wall and a corrugated inner wall.

FIGURE 15 illustrates in horizontal section a portion of a vertically disposed cylindrical container having concentric inner and outer walls 112i and 14 respectively. Support plates 2 1i and 26 are bonded in alternating relationship to the inner surfaces of the walls 12 and 14], respectively. The plates 24 and 2b] are disposed parallel to the axis of the container, and vertically spaced horizontal cables 28 are employed in the manner heretofore described. The cables 28 may be endless or they may be of finite length with their ends secured to one of the walls 12] or 14 If desired, the

plates

24 and 26 may be annular in shape and disposed at right angles to the axis of the container and the cables 28 strung vertically or helically. While the body of the container in this embodiment is constructed as a single cylindrical panel, it may be constructed, if desired, of a plurality of arcuate panels joined together edge to edge by means of circumferential tension bands and one of the heretofore described joint arrangements.

The construction shown in FIGURE 15 may also be employed as a vacuum jacketed pipeline in which the inner wall 12 is insulated from the atmosphere by the vacuum space. In this case the internal support structure also suspends the wall 12 within the wall 14 When employing either arcuate or cylindrical panels it will generally be desirable to allow for the greater expansion and contraction of the outer wall by means of a suitable expansion joint as indicated at 104 in FIGURE 15. This arrangement insures that all the vacuum load across the outer wall 14 is transferred through the cables 28] and

plates

24 and 26 to compress the inner wall 12 and that practically none of the vacuum load is taken in circumferential compression stress of the outer wall 14 itself. If the outer wall 14 took the compression load, then the inner wall 12 would be under tension from the vacuum load. This, added to the pressure stress from the contents within the container, would make it necessary to construct the inner wall 12 thicker in order to withstand the additional stress.

The expansion 104 can be omitted if the inner wall 12f is placed in compression and the outer Wall 14 in tension by tensioning the cables 28 to a high degree. By controlling the tension in the cables enough compression could be set up in the inner wall to make it allowably thinner than it would otherwise have to be. By accurate control of the assembly and the tension on the cables the total material in the inner and outer walls would need to be very little more than that required in a single Walled tank.

While the cylindrical'vacuum panel of FIGURE 15 serves as the container and thus requires relatively little material it will be appreciated that the container may be constructed as an ordinary tank and the vacuum panel added solely as an insulating jacket. The latter arrangement has the advantage that a leak in the tank does not affect the insulation system. If the jacket is constructed of arcuate panels, a further advantage is obtained in that one vacuum leak does not affect the entire vacuum system and can be more easily located.

FIGURE 16 illustrates a flat vacuum panel 10k which is constructed so as to be easily connectable to a similar panel along all four edges. As shown, the panel 10k has the exterior appearance of being constructed of two overlying panels which are offset from each other in a diagonal direction so as to form a step 168 along each edge. The panel has a single interior vacuum space provided with a support plate and cable system of the kind heretofore described. It will be apparent from inspection that the panel 10k can be joined to coplanar panels or to panels disposed at right angles thereto by fitting the steps 108 into engagement with corresponding steps on the other panels. 7

FIGURE 17 shows a refrigeration container 110 of telescoping box construction the walls of which embody the principles of the present invention. For simplicity the internal support plates and cables are omitted. The assembled container comprises an inner open ended box having side walls 112 and an end wall 114 telescoped into an outer open ended box having side walls 116 and an end wall 118. The inner transverse dimensions of the outer box are sufiiciently larger than the outer dimensions of the inner box that the

side walls

112 and 116 do not touch each other. A gasket 126 between the free ends of the side walls 112 and the inner surface of the end walls 118 forms a seal at this location. An additional seal is formed by a gasket 122 between the free ends of the side walls 116 and a laterally extending flange 124 on the closed end of the inner box. The

gaskets

120 and 122 become compressed as the boxes are drawn toward each other by means of bolts 12 6 passing through the flange 124. The primary advantage'of that arrangement is that the closure for the open end of the inner box is separated from the open end of the outer box by the full length of one

side wall

112 or 116.

In FIGURE 18 there is shown a panel whose inner and outer walls 12m and 14m serve as the inner cable sup porting means. In this construction the walls are shaped out of sheet metal so as to form ribs 128 which project into the vacuum space. The arrangement is similar to ordinary corrugations with an additional indentation at the apex of each valley. The ribs 128 serve'as supports for a tension cable 28m which takes the vacuum load in the manner heretofore described. Although heat transmission through the ribs 128 would be expected to be greater than through the

plates

24 and 26 of the other embodiments, the rib construction is more economical in requiring fewer parts. In addition it permits the panel to be slightly curved.

What is claimed is: 4

1. A thermally insulating hollow sealed structure having at least two spaced apart opposed walls defining therebet'ween a relatively thin elongated thermally insulating space,'and support and reinforcing means within said space for resisting collapse of said walls by forces acting externally thereon, said means including a plurality of spaced apart compression members projecting in a transverse direction relative to said space, adjacent members projecting into said vacuum space fromopposite Walls and having a free end facing the other wall, and at least one flexible tensioned member disposed and passing in a Wave pattern over the free ends of said compression members and applying compression thereto in a transverse direction relative to said space, whereby said walls are subjected to outward forces which resist external collapsing forces.

2. Apparatus as in claim 1 wherein said compression members are separate elements from said opposed walls and are secured at one end to the inner surfaces of said opposed walls.

3. Apparatus as in claim 1 wherein each of said compression members is integrally formed with the opposed wall from which it projects.

and wherein said tensioned member extends transversely to the corrugations.

6. Apparatus as in claim 1 wherein said structure has the shape of an annulus, one of said opposed walls defin-.

ing the inner wall of the annulus and the other opposed wall defining the outer wall of the annulus.

7. Apparatus as in claim 1 wherein said structure is a panel having a front surface defined by one of said opposed walls and a rear surface defined by the other of said opposed walls and at least one edge disposed generally transverse to said walls, said edge having a hollow stepped tongue-like structure extending generally parallel to said walls for mating with a complementary configuration on another panel.

8. Apparatus as in claim 7 wherein said tongue-like structure includes at least one recess and at least one projection adapted for interlocking with a complementary projection and recess on another panel.

9. Apparatus as in claim 7 including means for insulating the junction of said edge with one of said opposed walls, said insulating means including a sealed vacuum jacket defined by spaced-apart walls, said jacket overlying said junction.

10. Apparatus as in claim 7 wherein said tongue-like structure projects from said opposed walls at an angle thereby forming a corner on said panel.

11. Apparatus as in claim 7 in combination witha complementary panel, the tongue-like structures of the A two panels overlapping each other and terminating at their outer ends in flat walls which are inclined to the axis of the tongue-like structures, each of said inclined walls abutting a complementary wall on the other panel; and externally fastening means for drawing said panels together in the direction of the axes of said tongue-like structures.

12. Apparatus as in claim 1 wherein said structure is a panel having a front and rear surface defined by one of said opposed walls and a rear surface defined by the other of said opposed walls, said one opposed wall having a hollow evacuated flange projecting therefrom at a location inwardly of an edge of said one Wall whereby another panel may be fitted into the space between said flange and the edge. 4

13. Apparatus as in claim 1 wherein said structure is a fiat panel, said opposed walls being of parallelogram plan view and diagonally offset from each other thereby providing a tongue-like structure along each edge adapted to mate with complementary tongue-like structures on other panels.

References Cited UNITED STATES PATENTS 2,047,154 7/1936 Pimsner 52-404 2,495,405 1/1960 Bishop 220 9 3,064,317 11/1962 Dobson 220 1s 3,149,742 9/1964 Hay etal. 220-15 FOREIGN PATENTS 541,447 10/1955 Belgium.

T HERON E. CONDON, Primary Examiner.

J. B. MARBERT, Assistant Examiner.