US3224500A

US3224500A - Perimeter cooled cargo container

Info

Publication number: US3224500A
Application number: US159522A
Authority: US
Inventors: Bennett Walter
Original assignee: Utility Trailer Manufacturing Co
Current assignee: Utility Trailer Manufacturing Co
Priority date: 1961-12-15
Filing date: 1961-12-15
Publication date: 1965-12-21
Anticipated expiration: 1982-12-21

Description

1965 w. BENNETT PERIMETER COOL-ED CARGO CONTAINER 4 Sheets-Sheet 1 Filed Dec. 15, 1961 NM m.

INVENTOR.

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Dec. 21, 1965 w. BENNETT PERIMETER COOLED CARGO CONTAINER 4 Sheets-Sheet 2 MLTEQ fl bwiza 11 29 Filed Dec. 15, 1961 fie:

INVENTOR.

Dec. 21, 1965 w. BENNETT PERIMETER COOLED CARGO CONTAINER 4 Sheets-Sheet 5 Filed Dec. 15, 1961 mLTEQ flew/var;

INVENTOR.

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INVENTOR 4 Sheets-Sheet 4 Filed Dec. 15. 1961 United States Patent Ofilice 3,224,500 Patented Dec. 21, 1965 3,224,500 PERIMETER COOLED CARGO CONTAINER Walter Bennett, San Marino, Califl, assignor to Utility Trailer Manufacturing Company, City of Industry, Caiifi, a corporation of California Filed Dec. 15, 1961, Ser. No. 159,522 8 Claims. (Cl. 16553) The present invention relates generally to refrigerated containers for food stuffs or other goods and more especially to a vehicular container of this character.

It has been found advantageous to build temperature controlling, or refrigerated containers with air spaces in the walls through which chilled or heated air flows in heat exchanging relationship with the inner face of the wall and with the cargo space in order to keep goods in the cargo space at a desired temperature. Such containers may be either stationary or movable, the latter including refrigerated trucks, trailers, railroad cars and the like. The system as used for refrigeration is commonly referred to as perimeter cooling since the chilled air is circulated about the perimeter of the cargo space and not through the space itself.

Various advantages are obtained by this arrangement for cooling the cargo. A particular characteristic of the construction is that the cold air circulates out of contact with the cargo. This eliminates both extraction of moisture from the cargo by the cold circulating air as well as condensation of moisture within the cargo space. A even cooling is generally obtained since adequate air circulates around the cargo without reliance upon a particular stacking or arrangement of the cargo itself.

Particularly in the case of refrigerated Vehicles has it been found easier to load or unload. No particular pattern of loading is required and load dividers or the like are not needed to insure adequate air circulation for cooling. A refrigerated container of this character can be made with smooth inner walls that are easy to wash and to keep clean. This facilitates maintenance of the proper sanitary conditions.

Effectiveness of perimeter cooling in a refrigerated container depends upon various factors among which are free and substantially uniform air circulation throughout the walls of the container and cooling by the circulating air of as nearly as possible all of the interior areas of the container walls.

Another advantage of perimeter cooling is that the cooling air circulates in a closed circuit and does not have an opportunity to pick up moisture from the goods or from ambient air. Thus the cooling air remains dry and the cooling coils have little or no need for defrosting.

Air circulation through the walls is impeded by structural members which are necessary to hold the wall components in spaced relation and to give the necessary strength to the walls. This becomes a problem particularly in the case of the floor or bottom wall of the container where the structure required to support the cargo and other loads imposed on the floor may easily be so complex as to interfere with adequate air flow in all directions through the floor.

In previously known designs of perimeter cooled containers, the doors have not been cooled. Customarily the air circulation has not passed through the doors and as a consequence significantly large wall areas have not been cooled.

Thus it is a general object of the present invention to provide a novel design for a temperature controlling, for example a refrigerated container of the perimeter cooled type that provides for maximum cooling, efficiency by obtaining maximum freedom of air flow through all of the walls, including the floor, and by cooling the maximum possible area of the inside face of the walls, including doors.

How the above as well as other objects and advantages of the invention are achieved will be more readily understood by reference to the following description and to the annexed drawing, in which:

FIG. 1 is a combined vertical longitudinal section and side elevation of a semi-trailer embodying a preferred form of the present invention. FIGS. 1, 2 and 6 are, in part, schematic in which thin metal skins are shown in single lines.

FIG. 2 is a vertical transverse cross section through the trailer on line 22 of FIG. 1.

FIG. 3 is an enlarged fragmentary transverse cross section, as in FIG. 2, showing the bottom wall or floor structure of the trailer and portions of the two side walls.

FIG. 4 is a fragmentary vertical longitudinal section through the lower wall or floor structure of the trailer on line 44 of FIG. 3.

FIG. 5 is an enlarged fragmentary perspective at a lower longitudinal corner of the trailer showing the construction of the bottom wall or floor structure of the trailer and also a side wall thereof.

FIG. 6 is a horizontal section through the top wall of the trailer immediately below the layer of insulation, as on line 66 of FIG. 1.

FIG. 7 is an enlarged fragmentary vertical longitudinal section through the top wall of the trailer.

FIG. 8 is an enlarged fragmentary perspective view of a lower rear corner of the trailer showing the connection between air circulation spaces in the bottom wall of the trailer and in a side hinged door in the rear wall of the trailer.

FIG. 9 is an enlarged fragmentary perspective of an upper rear corner of the trailer showing construction of the top wall and of the side hinged door in the rear wall of the trailer.

FIG. 10 is an enlarged fragmentary perspective of a lower longitudinal corner of the trailer showing the construction of the bottom wall of the trailer and of a side hinged door in the side wall of the trailer.

In the drawing, there is shown a preferred embodiment of the present invention as applied to the construction of a semi-trailer, or as it more generally termed herein, a trailer. It will be realized that such disclosure is not limitative upon the present invention, because the inven tion may equally well be applied to any container, including other types of vehicles, including trucks, railroad cars, and etc.

Generally speaking, the refrigerated vehicle of the present invention comprises a body 10 mounted upon any suitable type of running gear, such as the double axle assembly indicated generally at 12. The body is provided with one or more doors. It is common practice to build such trailers with rear doors 14, but the invention may equally well be applied to a side door 15, as will be explained. Although it is customary for the rear doors 14 to be of such a size that they actually constitute substantially the entire rear wall of the body, these doors, like side door 15, may be only a portion of the wall and close an opening therein. Such doors are customarily designed to swing about vertical axes and are referred to herein as side-hinged.

In a broad aspect, the vehicle body of the present invention comprises outer shell 17 and inner shell 18 which is inside of and spaced from the outer shell. As is shown in greater detail in FIG. 3 and subsequent figures, the outer shell comprises a layer 19 of thermal insulation adjacent an outer skin 20 that is usually, but not necessarily thin sheet metal. The inner shell 18 is preferably a metal heat conductive wall which is designed in its preferred form to present a smooth interior surface. At the top wall and the vertical side and end walls of the body, the inner shell is preferably a thin skin. In the fixed vertical walls, inner shell 18 is held in spaced relation to outer skin 20 and insulation 19 by vertically extending

members

75 and 76 which also give rigidity and strength to the walls. At the bottom wall or floor structure, since the shell is a load bearing member, the inner shell is preferably made with reinforcing ribs or other means, enabling the inner metal shell or floor panel to withstand the loads imposed upon it. In the floor structure the inner shell or floor panel is supported on a lower frame-in this case a part of the vehicle framingby load transmitting members spacing the inner floor shell from the outer shell and forming air flow channels as will be described. The two shells are held an fixed, spaced relation by various spacers, as will be further described, and which in the case of the bottom wall or floor involve rather extensive structure in order to support vertically the loads within the trailer. In addition, either of the two shells may include reinforcing or load bearing members as may be necessary, many of which will be pointed out as the description progresses.

With this construction, the inner shell is, as far as practical, a thin, sheet metal heat conductive box which encloses the cargo space within the trailer body. The outer shell is provided with and includes, all around, thermal insulating material which minimizes the rate of heat transfer between the cargo within the inner shell and the surrounding atmosphere. The two shells are spaced apart in order to provide passages for circulation of chilled air between them, the chilled air having access to a maximum proportion of the area of the inner shell in order to cool all parts of that shell and keep the cargo as far as possible uniformly at a desired low temperature. The cooled air is obtained by air circulation through a refrigerating unit having an evaporator 22 located preferably in the forward portion of the trailer and provided with a fan 23 which forces air over the evaporator coils to be cooled and thence rearwardly within the space or air passage 39 in the top body wall between the inner and outer shells. As the chilled air flows rearwardly above the inner shell, a part of it is laterally diverted to flow downwardly through intershell spaces or air passages 21 in the side walls of the trailer and also through space 44 in the rear or end wall. The chilled air returns through the air passage 29 in the bottom wall or floor structure of the body underneath the floor panel and then upwardly within the space 24 at the forward end of the body between the outer and inner shells. This general air circulation is shown in FIGS. 1, 2, and 8.

To permit this air circulation, air passage 39 in the top wall or roof structure communicates laterally with the upper ends of air passages 21 in the side walls (FIGS. 2 and 6) and longitudinally with the upper end of the air passage 44 in end wall 14. The 'lower ends of air passages 21 in the side walls and of air passage 44 in the end wall communicate respectively laterally and longitudinally with passage 29 (FIGS. 2, 5 and 8) in the lower wall or floor structure. And floor passage 29 communicates at its end opposite end wall 14, with the lower end of end wall passage 24 (FIG. 1). How the floor structure passage 29 provides for lateral flow from the lower ends of side wall passages 21, and for longitudinal flow to the end wall passage 24 is explained later.

The construction of the bottom wall or floor structure of the trailer body is more complicated than the construction of the side walls because it is necessary to transmit the loads imposed from above on the floor panel through the floor structure to the frame of the trailer, while at the same time allowing longitudinal and transverse air circulation between the inner and outer shells. The loading imposed by the cargo is distributed more or less uniformly over the entire floor area and does not pose as much of a problem as do the concentrated loads created by a fork lift truck or the like moving in and out of the trailer body during loading and unloading operations. The construction of the bottom wall or floor structure of the trailer is shown in detail in FIGS. 3, 4 and 5.

At this location in the body, the metallic heat conductive inner shell has a floor panel 25 which is a relatively thin metallic sheet with a smooth upper surface and which is reinforced on its under side by a plurality of laterally spaced metallic longitudinal ribs 26. The floor panel is preferably made from extruded members so that the ribs 26 are integrally formed with the top sheet. The particular type of floor panel here illustrated combines the advantages of high strength to support concentrated load and a smooth upper surface; but it will be realized that it is within the scope of the invention to use other types of floor panels.

The

floor panel

25, 26 rests upon a plurality of elongated transverse and preferably wooden support elements 27 which preferably extend for the. full transverse width of the inner shell. As may be seen in FIG. 5, these transversely extending support elements are spaced apart longitudinally of the vehicle, the spacing being governed by the strength of the floor panel itself since the panel rests upon the support members 27 which are in direct support of the floor panel.

The transversely extending members 27 are in turn supported by a plurality of longitudinal wooden stringers 28 extending longitudinally of the vehicle body and spaced apart transversely of the body. Stringers 28 rest upon and are supported by metallic cross beams 30 which in turn transmit entire weight of the cargo to the trailer longitudinal frame by connections not shown in the drawing. Cross beams 30 may be regarded as parts of the trailer frame. The skin sheet 20a of the outer shell 17 is attached to the under faces of cross beams 30. In order to reduce the heat transfer between the inner and outer shells through the floor supporting structure, the supporting elements 27 and stringers 28 are made of any suitable material having a relatively low heat conductivity, as for example wood. Between the outer shell insulation 32 and the inner floor-panel shell is a space in the bottom wall or floor structure of the trailer, generally indicated at 29, through which chilled air can circulate both longitudinally and transversely of the vehicle. As seen particularly in FIGS. 4 and 5 the frame members 30 are embedded in the heat insulating layer 32.

Stringers 28 are designed to permit both longitudinal and transverse flow of air through the inter-shell space 29 with as little obstruction as possible. For this purpose they provide openings at intervals along their length. This may be done by forming openings in the stringers themselves; but in the present design it is accomplished by interrupting the stringers, as shown in FIG. 4'. Thus an individual stringer 28 spans at least two beams 30 then may be discontinued to leave a gap between it and the next stringer section. Air circulation is also improved by spacing the stringers above the layer of insulating material 32. This naturally occurs when the insulating material 32 is a layer of urethane foam Wll'llCh is formed in place since it naturally tends to be depressed between two successive cross beams 30, as shown in FIG. 5. Freedom of air circulation can be improved by raising the bottom surface of stringers 28 above the top surface of cross beams 30, in any suitable manner. In the embodiment illustrated, this is accomplished by resting the ends of stringers 28 on pads 33 which not only space the stringers above the layer of insulation but increase the bearing area of the stringers on the cross beams. The longitudinally extending stringers 28 thus direct the air circulation in passage 29 between the inner and outer shells of the bottom wall of the trailer in a direction longitudinally of the body; but at the same time there are sufficient openings under, over and through the stringers to provide free transverse circulation of the air so that the air entering the floor space from the side walls can mingle freely with the stream of air moving in a longitudinal direction. FIGS. 3 and 4 show how the transverse air channels between cross members 27 and over and under, and between the stringers 28, are open at their ends, at the side edges of the floor structure, to the lower ends of passages 21 in the side walls. It will be noticed that the

support members

27, 28 and 33 also serve the function of spacers which keep the inner shell, consisting of floor sheet and ribs 26, spaced and insulated from the outer shell consisting of the outer skin sheet 20a, cross beams 30, and the layer of insulating material 32.

A stressed-skin type of construction is preferred and illustrated. Hence the side walls are in eflect load bearing trusses and the cross beams extend laterally of the vehicle to bring their ends under the side walls. The ends of the cross beams are attached in any suitable manner, not shown, to the horizontal web 34a of the longitudinally extending structural member 34 at the bottom of each side wall of the body.

The construction of the top wall of the trailer body is shown in FIGS. 2, 6 and 7. Here the inner shell, as before comprises a single metallic sheet 18 and the outer shell comprises an outer skin sheet or roof 2% inside which is a layer of insulation 19. The outer shell in this case is supported from and spaced above the inner shell by a plurality of laterally spaced longitudinally extending wooden members 35 which also act as guide vanes or baffles to direct the flow of chilled air through the inter-shell space in the top wall of the trailer body. These wooden members 35 extend longitudinally of the trailer body, al though, as may be seen in FIG. 6 some of the member disposed towards the side of the body are inclined in order to distribute and divert a portion of the chilled air into the upper ends of the inter-shell space in the side walls of the trailer body.

As may be seen in FIG. 7, a plurality of transverse rafters or beams 36 is used to support roof sheet 20b of the outer shell, these beams being of angular shape. Although an approximately Z shape is shown, it will be realized that a channel or other shape could equally well be used. Fastened to the web of each beam 36 are angle brackets 37, the connection between the beam and each bracket including a washer 38 of any suitable material having a low heat conductivity in order to impede the transfer of heat through the

metal members

36 and 37. The inner end of each angle bracket 37 is attached to one of the longitudinally extending wooden members 35, this assembly of parts thus serving to space the inner shell 18 from the outer shell (2% and 19) as well as to provide a self supporting, rigid top wall for the trailer.

As shown in FIG. 7, the layer of thermal insulating material has a thickness substantially equal to the combined projection of

members

36 and 37 from sheet 20b so that these angle members are completely embedded in the thermal insulation. As a consequence of this construction, the outer shell of the top wall together with its insulation 19 is spaced from the inner shell, sheet 18, by a distance approximately equal to the vertical dimension of the wooden members 35; and it chiefly is in this space 39 between the two shells through which air from evaporator 22 flows rearwardly and laterally of the trailer body.

A feature of the present invention is the design of doors in vertical walls of the vehicle in such a manner that there is continuity of cooling in the sections of the walls formed by such doors. To do this, each door is formed by laterally spaced sections of the inner and outer shells so that the air circulating space between the shells is continued through the doors; and this air circulation space in each door is connected at the top and the bottom to the

air circulating space

39 and 29 in the top and bottom body walls respectively. These connections between the air circulating spaces can take different forms, depending upon the size and location of the door. Typical connections will now be described.

FIG. 8 shows the design of a rear door 14 having an internal air circulating space 44 connected at its lower end to the air circulating space 29 in the bottom wall of the body. Door 14 is a flush type door, that is, it forms in effect a continuation of a wall structure at either jamb thereof, although it will be noticed that in the case of the rear doors 14 the two doors themselves constitute substantially the entire rear body wall in order to obtain a maximum size opening through which cargo can be loaded and unloaded. The pair of doors 14 are each adapted to swing about a vertical axis at one side, a typical hinge 40 for this purpose being shown in FIG. 8. Thus a door may be regarded for practical purposes as a movable wall section. A plurality of hinges of this character are provided along one side for each of the doors.

From FIG. 8 it will be seen that each door 14, the two doors being substantial duplicates of each other, is formed with spaced sections of the inner and outer shell similar to the other walls of the trailer body. Thus sheet 41 on the inside of the door functions as a portion of the inner shell structure 18 and the outer sheet 42 together with the adjoining layer of insulation material 43 is a section of the outer wall structure 17. The space between inner plate 41 and insulation layer 43 is the inter-shell passage 44 through which chilled air circulates and which is connected with similar spaces in the fixed walls of the trailer body. Along the jamb at the hinged side of the door the space 44 is closed by channel 45 which supports sheet 41 and extends vertically along one edge of the door. The bottom edge of the door is closed by an angular plate 47 attached to the lower edge of sheet 41 and to the door frame. Plate 47 is provided with a plurality of openings 48 through which air may flow, in this case from the space 44 outwardly to the space under 47 below and interior of the door. The openings 48 are preferably located in a horizontally extending section of plate 47 in this specific embodiment. The door includes other frame work, not specifically mentioned, which connects the vertically extending channels 45 and the lower edge of plate 47 with outer panel 42 in order to provide a rigid, unitary door structure.

Each door 14 also includes a pair of

flexible sealing members

50 and 51 each of which extends around the entire perimeter of the door. These flexible seals are carried by the door and move with it to engage fixed portions of the trailer body at locations which will be further described, in order to effect continuity between the air spaces.

Additional sealing members

52 and 53 are preferably used but are optional.

From FIG. 8 it will be seen that floor panel 25 is supported along its rear edge by a transversely extending beam 54. Between beam 54 and the top sheet 25 of the floor panel, is strip 55 across the ends of the reinforcing ribs 26 in order to seal off the ends of the spaces between ribs 26 in the floor. Beam 54 is supported upon spaced members 56 on plate 57 and transverse member 59 which are directly supported by a cross beam 60.

The inner or forward end of plate 57 is bent upwardly and then rearwardly as illustrated at 58 in FIG. 8 but preferably is spaced below the floor panel suflicientlv to allow air to flow between the baffle at 58 and the floor panel above it.

The purpose of this construction is to allow access of air to the inter-shell space 29 in the bottom wall of the trailer by passing, from the door space 44 down through 48 into the space below 47 and then through the space provided by supports 56 between beam 54 and plate 57 and then up and over baflle 58. The tortuous path required to be followed by the air, as indicated by the arrows in FIG. 8, does not hinder free access of air to the space 29. However, as a result of this baffle construction, this space is kept free of any water which might enter from a hose directed horizontally against the end of the floor structure when the trailer body is being cleaned, especially when the interior is being washed out. It also prevents ingress of moisture from condensation within the body.

Sealing members

50 and 51 are flexible strips of rubber or rubber-like material. In part strip 50 is at the lower edge of inner shell 41 in a position to close the gap between the lower edge of that shell and the top surface of floor panel 25. Sealing member 51 extends across the bottom of door 14 at a position to close the gap between plate 47a and the top of plate 57. Consequently the two

flexible seal members

50 and 51 carried at these points on the door engage respectively substantially horizontal surfaces on the inner and outer shells of the floor. As the door swings, the sealing members slide over the surfaces in sealing engagement therewith. At the vertical edges of the doors, the

seals

50 and 51 are pressed against an opposing fixed surface at the jamb and on the other door. Where two doors come together, the seals overlap.

Summarizing the structure at this part of the trailer body, as illustrated in FIG. 8, it will be noticed that sheet 41, the inner shell of the door, terminates at its lower edge closely above sheet 25 of the floor and adjacent the rear end thereof. Plate 57 extends rearwardly of the rear edge of floor sheet 25, thus extending the outer floor shell rearwardly beyond the inner shell of the bottom wall of the trailer.

The vertical flange plate 47a of plate 47, being located in contact with insulation 43 is in effect the inner face of the outer shell of the door; and plate 47a terminates at its lower edge closely above plate 57 adjacent the rear end thereof. Plate 47a is spaced rearwardly from the face of .channel 54. Thus angular plate 47, 47a with elements of plate 57 and members 54 and 55 combine to form a chamber that extends horizontally across the width of door 14. This chamber communicates at 48 with the open lower end of air passage 44 in the door and beneath channel 54 with the open rear end of adjoining air passage 29 in the bottom wall. These structural elements are complementary formations that are in part on the door and in part on the bottom wall. When brought together by closing the door, these complementary formations provide continuity of air flow downwardly from the door into the return passage beneath floor sheet 25.

These complementary formations are separable to allow the door to open. When they are brought together to form a chamber through which chilled air circulates to adjoining walls, they have two joints at spaced positions that are preferably closed by sealing means in order to make the chamber sufficiently tight to avoid undue loss of chilled air. Such sealing means might take any suitable form; but shown here these means are the flexible sealing strips 50 and 51, especially where they extend across the bottom edge of the door. When the door is closed, these sealing strips engage the fixed bottom wall of the trailer body. The sealing strips extend upwardly along the vertical edges of the door since it is also desirable to close off the joint between the two doors and between the door and the fixed portion of the walls to prevent loss of chilled air from the interior cargo space of the trailer.

The same construction with a few minor changes may be used if the door is in a side wall of the body, as for example door 15 which closes an opening in a vertical side wall of the trailer. FIG. shows such a side-hinged door that swings about a vertical axis established by a plurality of hinges 40, of which only one is shown in FIG. 10. Door 15 closes an opening and is set into the wall so that it is in effect .a continuation of the wall. The various parts of door 15 and of the bottom wall of the the trailer have been given the same reference numerals in FIG. 10 as in FIG. 8 where the parts perform the same function and have the same relative position.

The only notable change from the construction shown in FIG. 8 is a change in the configuration of the insulating layer 43 and the position of openings 48. It will be noted that in FIG. 10 the layer 43 of thermal insulation is recessed or undercut along the lower portion of the layer and is therefore at all points spaced from plate 47 and especially the vertical portion thereof 47a. As a consequence, the air passage 44 within the door extends downwardly to the door framing members at the bottom of the door instead of stopping at the horizontally extending portion of plate 47. This change in the shape of the insulation layer allows the holes (48 in FIG. 8) in plate 47 to be moved to the position of 48a in FIG. 10 in the vertically extending portion 47a of the plate 47.

It is preferable to use the same bafile formation 58 at a side door as at a rear door on the trailer to eliminate the possibility of water accidentally entering into the air passage 29 underneath the floor panel. In this case the baffle comes up underneath the transversely extending planks 27 but there is still room for air to circulate laterally of the vehicle by entering or leaving the floor passage 29 through the spaces above baffle '28 and between the spaced transverse members 27, and underneath the floor panel.

FIG. 9 shows the construction at the top of door '14 (and also door 15), a construction which differs substantially in appearance from that already described but which embodies the same principles. At the extreme rear end of the top wall of the body, air passage 39 is preferably narrowed by offsetting inner shell 18 upwardly. This is accomplished in any suitable way, as by angular plate in which there is a plurality of openings 66 arranged in a row adjacent the rear end of air passage 39 allowing air to leave passage 39.

The upper end of air passage 44 in door 14 is closed by channel shaped member 67 which extends between the two sealing strips 50 and '51. Channel 67 has in it a plurality of openings 68 which provide communication with the vertically extending air passage 44 in the door. When the door is in the closed position of FIG. 9, sealing

members

50 and 51 engage the under surface of plate 65 at opposite sides of the row of openings :66. Plate 65 and plate 67 being parallel to each other, the space between them bounded laterally by seals 50 and '51 becomes the closed chamber communicating with the open end of each of the air passages in the two walls of the trailer body represented by doors '14 and '15 and the top wall.

Although there is relatively little danger of accidentally forcing water into upper air passage 39 when the door is open, because the water will normally tend to run out of openings 66, yet it may be desired to provide means to prevent entry of water at this point. For this purpose it may be desirable to add a baflle plate 70 which is attached to the upper face of plate 65 and extends upwardly and rearwardly towards openings 66. Additional safeguard is obtained by providing a second bafile 71 which is downwardly and forwardly directed and is located between baflle 70 and openings 66. The latter baffle deflects downwardly any water projected upwardly through an opening 66 and the two bafiles together provide a tortuous path which the air can follow but which intercepts any particles of water driven through openings 66.

One particular advantage of the arrangement shown in FIG. 9 is that the openings 66 arranged in a row across the head of the doorway at the rear of the truck, project downwardly a stream of chilled air which is cooler and therefore denser than the ambient air. Consequently when the doors are opened to load or unload cargo, an air curtain effect is obtained by maintaining circulation in passage 39 and exhausting cold air in a downwardly directed curtain across the doorway. This'tends to keep the cold air in the cargo space and exclude the entry of warmer air from outside.

The complementary formations on the doors and the fixed walls'of the trailer so far described have been designed with particular reference to the location of either the top or the bottom of the door in order to obtain certaln advantages. However it will be realized that the const-ructions may be interchanged if desired or that various other modifications may be made in them while still obtaining continuity of air flow from a fixed Wall into the movable wall section represented by the door.

I claim: 1. In a temperature controlled goods container, the combination of substantially vertical side and end wall structures, a

substantially horizontal top wall structure and a substantially horizontal bottom wall structure in the nature of a goods supporting floor structure, said structures enclosing a goods-containing space; at least one end wall structure, and the top and side wall and bottom floor structures each comprising an outer shell which includes a heat insulating layer together with an inner heat conductive shell spaced from the outer shell to provide in each of said structures an air flow passage substantially co-extensive therewith, the inner shell of the bottom floor structure being in the nature of a heat conductive goods carrying floor panel, the air flow passage in the top wall structure communicating laterally with the upper ends of the air flow passages in the side wall structures substantially throughout the end-wise lengths of said passages, the air flow passages in the side wall structures being open for vertical air flow therethrough and communicating at their lower ends with the lateral edges of the air flow passage in the bottom floor structure substantially throughout the lengths of said air flow passages, and the air flow passage in at least one of the horizontal wall structures communicating at a length-wise end with the air flow passage in said one end wall structure, means setting up air circulation through said air flow passages, air flow directional vanes of low heat conductivity in the air flow passage of the top wall structure diverting at least a part of its longitudinal air flow laterally between its interior and its lateral communications with the air passages in the side wall structures, and means structurally supporting the inner floor panel of the bottom floor structure on and spacedly above underneath framing associated with the outer shell of the bottom floor structure, said means being of low heat conductivity and embodying longitudinally spaced and laterally extending supporting members establishing between them lateral air flow channels in communication with the lower ends of the air flow passages in the side wall structures and longitudinally extending and laterally spaced supporting members establishing between them longitudinal air flow channels in intercommunication with each of the lateral air flow channels, the longitudinal air flow channel of at least one of the horizontal wall structures communicating with the air flow channel in said one end wall structure. 2. The combination defined in claim 1 and in which the longitudinal air flow channel of the bottom floor structure communicates at one end with the lower end of the air flow passage in said one end wall, and the means setting up air flow is applied to the end of the air passage which is adjacent said one end wall in the upper wall structure to set up longitudinal air flow through that upper wall passage from that end. 3. The combination defined in claim 1 and in which the means structurally supporting the inner floor panel on the underneath framing includes a plurality of elongated support elements extending transversely of the container and spaced apart longitudinally thereof, said elements being in direct support of the floor panel, and a plurality of longitudinally extending transversely spaced stringers supporting the transversely extending elements and supported on the underneath framing, said elements and stringers being of relatively low heat conductivity,

at least the longitudinal spacings between the transverse support elements forming between them transverse air circulation channels open at their ends at the side edges of the floor panel and communicating with the lower edges of the air flow passages in side wall structures,

and the transverse spacings of the longitudinally extending stringers forming longitudinal air circulation channels in intercommunication with each of the transverse circulation channels.

4. In a temperature controlled goods container, the combination comprising:

an enclosing wall structure comprising an outer shell including a layer of thermal insulation and an inner shell inside and spaced from the outer shell, the inner shell having a heat conductive metallic floor panel providing a load supporting deck;

the outer shell under the floor panel embodying load supporting transverse framing with longitudinally spaced cross beams embedded in the layer of thermal insulation,

and support structure under the floor panel supporting the inner shell on the framing of the outer shell while permitting air circulation in the inter-shell space, said support structure comprising a plurality of elongated support elements extending transversely of the container and spaced apart longitudinally thereof, said elements being in direct support of the floor panel,

and a plurality of longitudinally extending transversely spaced stringers supporting the transversely extend ing elements and supported on the transverse framing, said elements and stringers being of relatively low heat conductivity,

at least the longitudinal spacings between the transverse support elements forming transverse air circulation channels open at their ends at the side edges of the floor panel,

and the transverse spacings of the longitudinally extending stringers forming longitudinal air circulation channels in intercommunication with the transverse circulation channels.

5. The combination defined in claim 4 and in which there are openings through the longitudinally extending stringers, said openings also providing transverse air circulation channels in addition to the air circulation channels between the transversely extending elements.

6. In a temperature controlled goods container, the combination as in claim 4 in which the longitudinal stringers individually span at least two consecutive cross beams and provide openings at intervals permitting air to flow past the stringers in a transverse direction.

7. In a temperature controlled goods container the combination as in claim 4 in which the stringers are spaced from the insulating material between cross beams to permit air to flow transversely of the vehicle between the stringers and the outer shell.

8. Load bearing floor structure for a temperature controlled goods container, comprising in combination a lower outer wall shell including load supporting framing and a layer of thermal insulation,

an inner wall shell spaced above the lower shell, the

inner shell having a heat conductive metallic floor panel providing a goods supporting deck,

and spacing and supporting structure of low heat conductivity mounted on the lower load supporting framing and supporting the floor panel and embodying a plural set of elongated transversely extending and longitudinally spaced elements of low heat conductivity and a plural set of elongated longitudinally extending and transversely spaced elements of low heat conductivity, said plural sets being in inter-supporting relation,

the longitudinal spacings of the transversely extending elements forming transverse air circulation channels open at the lateral edges of the spacing and supporting structure, and the transverse spacings of the longitudinally extending elements forming longitudinal air circulation channels open at at least one longitudinal end of the spacing and supporting structure and in intercom-munication with the transverse air circulation channels between the transversely extending elements,

and transverse openings ext-ending through the longitudinally extending elements, said openings also providing transverse air circulation channels in addition to the air circulation channels between the transversely extending elements.

References Cited by the Examiner UNITED STATES PATENTS 896,313 8/1908 Moore 165-42 1 2 Crede 62'424 Hemjy 16 549 X Rodert 982 Protzeller 16 542 Weber 6'2-250 Adams 98-6 King 62-405 Allyne 62411 X Jones 6278 Bowman 18934 Le armont 986 Muir 1 89-34 ROBERT A. OLEARY, Primary Examiner.

CHARLES SUKALO, Examiner.

Claims

8. LOAD BEARING FLOOR STRUCTURE FOR A TEMPERATURE CONTROLLED FOODS CONTAINER, COMPRISING IN COMBINATION A LOWER OUTER WALL SHELL INCLUDING LOAD SUPPORTING FRAMING AND A LAYER OF THERMAL INSULATION, AN INNER WALL SHELL SPACED ABOVE THE LOWER SHELL, THE INNER SHELL HAVING A HEAT CONDUCTIVE METALLIC FLOOR PANEL PROVIDING A GOODS SUPPORTING DECK, AND SPACING AND SUPPORTING STRUCTURE OF LOW HEAT CONDUCTIVIT MOUNTED ON THE LWOER LOAD SUPPORTING FRAMING AND SUPPORTING THE FLOOR PANEL AND EMBODYING A PLURAL SET OF ELONGATED TRANSVERSELY EXTENDING AND LONGITUDINALLY SPACED ELEMENTS OF LOW HEAT CONDUCTIVITY AND A PLURAL SET OF ELONGATED LONGITUDINALLY EXTENDING AND TRANSVERSELY SPACED ELEMENTS OF LOW HEAT CONDUCTIVITY, SAID PLURAL SETS BEING IN INTER-SUPPORTING RELATION, THE LONGITUDINAL SPACINGS OF THE TRANSVERSELY EXTENDING ELEMENTS FORMING TRANSVERSE AIR CIRCULATION CHANNELS OPEN AT THE LATERAL EDGES OF THE SPACING AND SUPPORTING STRUCTURE, AND THE TRANSVERSE SPACINGS OF THE LONGITUDINALLY EXTENDING ELEMENTS FORMING LONGITUDINAL AIR CIRCULATION CHANNELS OPEN AT LEAST ONE LONGITUDINAL END OF THE SPACING AND SUPPORTING STRUCTURE AND IN INTERCOMMUNICATION WITH THE TRANSVERSE AIR CIRCULATION CHANNELS BETWEEN THE TRANSVERSELY EXTENDING ELEMENTS, AND TRANSVERSE OPENINGS EXTENDING THROUGH THE LONGITUDINALLY EXTENDING ELEMENTS, SAID OPENINGS ALSO PROVIDING TRANSVERSE AIR CIRCULATION CHANNELS IN ADDITION TO THE AIR CIRCULATION CHANNELS BETWEEN THE TRANSVERSELY EXTENDING ELEMENTS.