US2696086A

US2696086A - Method and means for air conditioning

Info

Publication number: US2696086A
Application number: US136952A
Authority: US
Inventors: Frederick M Jones
Original assignee: U S THERMO CONTROL CO
Current assignee: U S THERMO CONTROL CO
Priority date: 1950-01-05
Filing date: 1950-01-05
Publication date: 1954-12-07
Anticipated expiration: 1971-12-07

Description

Dec. 7, 1954 F. M. JONES 2,696,086

METHOD AND MEANS FOR AIR CONDITIONING Filed Jail. 5, 1950 16 Sheets-Sheet l FIG. I.

INVENTOR. FREDERICK M. JONES ATTORNEYS Dec. 7, 1954 F. M. JONES METHOD AND MEANS FOR AIR CONDITIONING l6 Sheets-Sheet 2 Filed Jan. 5, 1950 INVENTOR. FREDERICK M JONES ATTORNEYS Dec. 7, 1954 F. M. JONES METHOD AND MEANS FOR AIR CONDITIONING l6 Sheets-Sheet 3 Filed Jan. 5, 1950 v INVENTOR. FREDERICK M. JONES ATTORNEYS Dec. 7, 1954 F. M. JONES METHOD AND MEANS FOR AIR CONDITIONING l6 Sheets-Sheet 4 Filed Jan. 5, 1950 ATTOR N EYS Dec. 7, 1954 F. M. JONES METHOD AND MEANS FOR AIR CONDITIONING l6 Sheets-Sheet 5 Filed Jan. 5, 1950 INVENTOR.' FREDERICK M. JONES ATTORN EYS 16 Sheets-Sheet G F. M. JONES METHOD AND MEANS FOR AIR CONDITIONING INVENTOR. FREDERICK M. JONES ,d/flizwzdg ATTORNEYS WB JWH JWH nun m Dec. 7, 1954 Filed Jan. 5, 1950 Dec. 7, 1954 F. M. JONES 2,693,036

METHOD AND MEANS FOR AIR CONDITIONING Filed Jan. 5, 1950 16 Sheets-Sheet T FIG. IO.

ELECTRIC/1 \ELEGTRIC E 4 ,X 52 153 HEATER INVENTOR. FREDERICK M. JONES ATTORNEYS Dec. 7, 1954 F. M. JONES 2,696,086

METHOD AND MEANS FOR AIR CONDITIONING Filed Jan. 5, 1950 l6 Sheets-Sheet 8 FIG. l2.

INVENTOR.

FREDERICK M, JQNES l ELECTRIC HEATER l ATTORNEYS 7, 1954 F. M. JONES 2,696,086

METHOD AND MEANS FOR AIR CONDITIONING Filed Jan. 5, 1950 16 Sh e'ets-Sheet 9 ATTORNEYS Dec. 7, 1954 F. M. JONES METHOD AND MEANS FOR AIR CONDITIONING l6 Sheets-Sheet 10 Filed Jan. 5, 1950 mhm - INVENTOR. FREDERICK M. JONES ATTORNEYS 7, 1954 F. M. JONES 2,6 6, 86

METHOD AND MEANS FOR AIR CONDITIONING Filed Jan. 5, 1950 1e Sheets-Sheet 11 E2 -332 mm. x. i 9 o o 6 L 336 INVENTOR.

FREDERICK M. JONES ATTORNEYS Dec. 7, 1954 F. M. JONES METHOD AND MEANS FOR AIR CONDITIONING 16 Sheets-Sheet 12 Filed Jan. 5, 1950 FIG. l9.

FIG. 20.

. INVENTOR. FREDERICK M. JONES ATTORNEYS 1954 F. M. JONES 2,696,086

METHOD AND MEANS FOR AIR CONDITIONING Filed Jan. 5, 1950 16 Shets-Sheet 13 INVENTOR. FREDERICK M JONES FIG. 28. FIG. 29.

ATTORNEYS Dec. 7, 1954 F. M. JONES METHOD AND MEAN S FOR AIR CONDITIONING l6 Sheets-Sheet l4 Filed Jan. 5

. B O 3 n F FREDERICK M.J ONES FIG. 34.

FIG. 33.

ATTORNEYS Dec. 7, 1954 F. M. JONES 2,696,086

METHOD AND MEANS FOR AIR CONDITIONING Filed Jan. 5, 1950 16 Sheets-Sheet 16 FIG. 37.

INVENTOR. 436 a FREDERICK M. JONES AT TORN EYS United States Patent METHOD AND MEANS FOR AIR CONDITIONING Frederick M. Jones, Minneapolis, Minn, assignor to The U. S. Thermo Control Co., Minneapolis, Minn, a corporation of Minnesota 7 Application January 5, 1950, Serial No. 136,952

32 Claims. (Cl. 62-4) My invention is related to a method and means of conditioning air and in circulating the same about and through an enclosed storage space. In general, the invention is concerned with a method and means of con-- trolling the temperature and humidity in and about an enclosed space such as the storage space of a transport vehicle used for the transportation of fresh or frozen foodstuffs and the like. More particularly it is concerned with a method and means of providing proper refrigeration within a railway vehicle used for the transportation of fresh or frozen cargoes such as perishable foodstuffs of all varieties and in maintaining substantially constant conditions within the controlled space despite changes in either direction of the atmosphere ambient to the carrier.

In recent years there has been a marked increase in the demand for fresh perishable foodstuffs and it has been a major problem to the transportation industry to transport such products from their source of origin to relatively distant markets because of spoilage in transport. It is estimated that the loss effected by spoilage amounts to approximately one-fourth of the gross value of the product. Moreover, even though. complete spoilage may not occur, the task of maintaining the conditions of certain products within an optimum range of temperature during transport is particularly critical, and this is most evident in certain forms of fresh vegetables and frozen foods. As one example, choice grades of eating apples which are maintained under cold storage conditions after harvesting, should be kept at a temperature of substantially 31 F. plus or minus 1. If the fruit is cooled below 29 F. it will freeze, and if the temperature is permitted to rise for any substantial period of time to a point above 35 F., decomposition sets in and in time the fruit becomes soft and pulpy.

The frozen food industry presents another type of problem. Foods which have been preserved by severe freezing can be kept in practically perfect condition for a year or more if they are maintained at temperatures ranging between l0 F. and 0 F. However, some of these foods such as fish, poultry, orange concentrate, and strawberries, and the like, will either spoil or change in flavor in a matter of hours if their temperature is permitted to rise to as much as +20 F.

Heretofore it has not been possible to maintain a substantially constant temperature within the storage space of refrigerator cars. nor has it been possible to maintain the space within these cars at 0 F. or lower for any substantial period of time.

In the prior art relating to the refrigeration of cargo carriers used on railroads, it has been the general practice to rely on the use of natural ice, or a brine solution refrigerated by ice, as the principal means of cooling the cargo space. In such carriers it is customary to provide bunkers at either ends of the car within which a large amount of ice is placed. Generally by means of fans operated from the wheel mechanism, the atmosphere within the enclosed space is circulated relative to these bunkers to cool the space. This means of providing refrigeration is expensive both from the point of view of the cost of the ice and brine, as well as the destructive effect of the brine upon the cars and associated equipment. In the conventional manner of transporting refrigerated cargoes, it is customary to re-ice the vehicles at stations along the right-of-way which are spaced about 300 to 400 miles apart. Thisis not only a costly means of refrigeration from the point of view of re-icing, but

where there are delays, it frequently happens that the temperature within the cargo space will have substantially exceeded the safe upper limits for the cargo, thus resulting in spoilage for which, if evident, the carrier must pay damages.

In further consideration of the problems arising out of the transportation of perishable products, there are times and occasions when the produce is moved from an area where climatic conditions are relatively warm to or through areas where climatic conditions are relatively cold, and under these conditions it is necessary to prevent the produce from freezing. In the prior art it has been customary to refrigerate the cars as they are passing through the warm climate, and as they approach the area of colder climatic conditions, to remove the ice from the bunkers and provide some means of supplying a small amount of heat to the enclosed space so as to maintain the temperature therein above the freezing point. Quite frequently it occurs that climatic conditions will change, or the cars will be delayed in transit, so that the changeover is delayed and the produce will spoil either by freezing or by such inaccurate control of the temperature as to permit a certain amount of decomposition to set in.

It is proposed to substitute mechanical condition con trol means to take the place of the natural refrigerating means. I am, of course, aware of the fact that there have been prior attempts made to use mechanical air conditioning means within railway cars. Insofar as 1 am aware, however, these prior art efforts have not been entirely successful because to a large extent the mechanical apparatus heretofore used has been made a permanent part of the car structure. A principal objection to this arrangement has been that the cost of installing me chanical equipment in the cars is excessive and in order to justify the expense, cars so equipped must be kept in substantially continuous use. Another defect of this arrangement has been that such mechanism, heretofore used, has not been able to withstand vibration and the severe shocks resulting from impact between the locomotive and the cars, and between the cars themselves 1 when a train is being made up or separated. Practically every time a train is made up, the cars are shunted along various tracks where they slam into each other during the connecting operations. Not infrequently cars will be traveling at rates from two to seven or eight miles per hour at the time they impact a string of stationary cars, and the result of such impacts is to cause disconnection of essential parts, and fatigue of other parts which almost always result in leakage of the essential refrigerating fluid. I am further aware of the so-called package units, one of which is shown and described in Numero and Jones Patent 2,303,857, and another of which is shown in the Jones Reissue Patent 23,000, both of which are assigned to the present assignee. Both of these units are provided with a portion containing the operating mechanism which is normally positioned on the outside of the vehicle, and a condition-changing portion which is normally maintained on the inside of the vehicle. In the one disclosure the unit is mounted beneath the vehicle body while in the other disclosure the unit is mounted in an upper wall portion of the vehicle body. The pres ent invention contemplates certain improvements over either of these former disclosures.

In the present invention I have provided an improved means of controlling both the temperature and the humidity conditions within a transport vehicle by providing what I consider to be an entirely different concept of air conditioning both as to the vehicle, the mechanical apparatus used for controlling the condition of the air, and the control of the mechanical apparatus.

Insofar as the vehicle itself is concerned, I have provided a structure which includes an internal chamber provided with damper controlled vents and which is insulated from the walls of the vehicle and within which the cargo is carried. At one end of the car and within an area which is substantially equal to one of the ice bunkers found in prior art cars, the mechanical air conditioning structure is mounted. The mechanical structure is a complete unit which may be bodily removed from the car, and includes a heat transfer portion which extends into a part of the enclosed chamber but is separated from the cargo-carrying portion by a partition which forms a passage through which the air is passed in heat exchange relationship as it leaves the cargo chamber and is thereafter returned thereto. The separated portion of the chamber actually extends to the one end of a car so as to form separated compartments on either side thereof at the end of the car. Within each of these separated compartments an independent mechanical air conditioning unit is removably mounted through an opening in a lateral side of the car adjacent its end wall. Each of the units is thus carried entirely within the car and has its heat exchange portion extending in opposition to a similar portion of the other unit through restricted openings into the passage located at one end of the chamber.

In one modification the enclosed chamber is composed of live walls of material having a low thermal drop therethrough and is open on its remaining side. in addition to being insulated from the car structure, the chamber is also separated therefrom so as to form an insulated passage or air duct about the five sides of the chamber. This duct or air passage communicates with the heat exchange passage that contains the air conditioning device and a circulating fan. The heat exchange passage communicates with the interior of the cargo chamber adjacent the open side thereof. One of the walls of the cargo chamber is provided with a series of damper controlled openings disposed in spaced relationship across the wall so as to form entry ways between the general air duct and the interior of the chamber and when the dampers are in an open position permit a portion of the circulated air to pass through the interior of the cargo chamber and in direct contact with the lading therein. The damper controlled openings are opened at the outset of the transit period for precooling the cargo space and the cargo itself after loading to assure a quick reduction of the temperature of the cargo to a desired transit temperature, after which the dampers are closed so that the circulated air in the general air passage passes about the exterior of the chamber and in contact with the outer surfaces thereof before returning across the open side thereof to the inlet opening of the heat exchange passage, thus minimizing contact between the circulated air and the lading within the chamber.

Under certain conditions it may be necessary to humidify the air to prevent dehydration of the cargo, and to supply this need, moisture absorbent means is carried by the car over which the conditioned air is passed prior to entering the chamber.

In another modification the conditioned air is introduced directly into the top of the chamber whence it is distributed in proportioned amounts throughout the length of the chamber both at the center and sides thereof to descend into the enclosed space and thereafter be withdrawn at one end of the chamber where, as in the preceding modification, it is passed downwardly over the heat exchange portion before being returned to the chamber.

When the heat exchange portion is operative to change the condition of the air, air circulating means is in continuous operation to continuously move the air cyclically from the chamber downwardly over the heat exchange portion and thence back to the chamber. During periods when the heat exchange portion is inoperative, as by way of a satisfied condition within the chamber, an auxiliary air circulating means is placed in operation, so that the air is always being circulated within the compartment.

In order that the air conditioning units may be readily inserted or removed from the car, they are each mounted on a frame structure which includes a slidably movable portion which is capable of extending outwardly through the opening in the side wall of the car so that the unit may be readily mounted thereon or removed therefrom by a winch. To prevent the units from being tampered with by unauthorized persons, the respective openings through which they are inserted into the car are closed by a sliding door. As these doors occur at the ends of the car, and to provide accommodation for the train crews, each of the doors carries a ladder which telescopically slides with respect to a stationary ladder portion positioned on the car above the door. To prevent the door from being opened by unauthorized persons, a locking mechanism cooperates with the door control means to lock the door in its closed position. To avoid any possibility of a car being dispatched with its doors open, the means for opening and closing the doors constitutes a 4 key for controlling the locking mechanism. This key, which is in the form of a crank, will be supplied only to persons authorized to have access to the air conditioning units.

As the operative portion of each of the air conditioning units includes an internal combustion engine, means must be provided for disposing of the exhaust gases as well as the heat generated by the engines, and for this purpose I have provided within each of the aforementioned compartments a hood structure which includes a vent pipe that extends through the upper wall of the car. The hood structure fits directly over the top of the operating portion of the air conditioning device, but is connected to the frame structure which supports the device so as to be telescopically movable when the door is opened and the device is slidably moved outwardly on its frame for replacement. The hood contains a thermostatically operated damper for returning a portion of the heated air to the operating portion when climatic conditions are such that a portion of the heat should be returned to maintain the engine and its cooperating parts in a heated condition.

The air conditioning units themselves each constitutes a unitary casing within which the several portions of the device are divided into an operating portion including an engine, compressor, condenser, and a fan for cooling the condenser. and a heat transfer portion which includes an evaporator having a driven fan above it for forcing the air downwardly in heat exchange relationship with the evaporator. A set of dampers are mounted in the casing portion above the evaporator and are operable to prevent the circulation of air during a defrosting operation. These dampers, however, will remain open during either heating or cooling of the air. The operation of the dampers is controlled by a fluid system, which is circulated when the engine is operating.

The refrigerant fluid system of the unit, which includes the compressor, condenser and evaporator. are interconnected by a control valve which is operable to completely reverse the flow of refrigerant so that the functions of the evaporator and the condenser may be reversed. The operation of this valve is normally automatic, and is controlled by an electrical system.

As mentioned above, the air conditioning units may be used to either heat or cool the storage chamber, and their operation for either purpose are controlled by a control system which is capable of initially starting and stopping one of the engines in response to the condition within the controlled space. in the event that the one unit is capable of maintaining the desired condition within the controlled space, or should for any reason become inoperative, the control system provides means for initiating the operation of the other unit which normally serves merely as a standby unit. The system also includes means for automatically changing the function of the air conditioning units from cooling units to heating units so as to maintain a substantially constant condition within the controlled space when the vehicle moves through changing climatic conditions. When the units are used in conjunction with a car during the winter season, there is always the possibility that climatic temperatures may be so low as to eventually cause the engines and their cooperating elements, including the lubricating fluid, to be cooled down to an inoperative temperature. This condition could arise when the temperature within the controlled space remains static for a substantial period of time To remedy these conditions, the control system includes means for starting the engines solely for the purpose of running them long enough so that they will always remain sufiiciently heated to be operative.

As has been previously mentioned, during the periods when the air conditioning units are not in operation, one or more fans are provided for circulating the air within the enclosed space to maintain a relatively uniform condition throughout the space. This fan or fans are operated from the battery current normally used for the starting of the engines, each of which has its own set of batteries. Assuming a condition where one of the batteries may be relatively weak from long usage, the electrical system includes means for selecting the source from which the current needed for the fan will be derived.

As a refrigerator car, like any other transport car, is scaled when its cargo is loaded, it is not possible for persons responsible for the safe transport of the cargo to be aware of the conditions within the enclosed space. Ac-

cordingly, control panels are mounted on either side of the car adjacent the openings through which the units are inserted. The panels include indicating means for show ing the condition of the enclosed storage space and also means for pro-setting the temperature at which the space will be maintained. The panels also include visual means for showing the operating condition of each of the mechanical air conditioning units and is capable of indicat ing whether these units are operating on either the re frigerating or the heating cycle or if they are momentarily inactive, whether the circuits are in proper condition so that the units are capable of operating when the need requires the same. Since the cars containing these panels will be moved during the hours of daylight and darkness, the last named indicating means include a plurality of lights which will enable an inspector to tell the condition of each of the cars as they are moved past a fixed point.

The supply of fuel necessary for the operation of the engine, and suitable batteries for starting and ignition as well as supplying current for other circuit needs, are carried by the car independent of the units. Means are provided for simply and easily connecting the fuel supply, the current supply and the conductors to and from control portions to the units by easily detachable means so that either unit could be removed in a relatively few minutes and if desired, replaced by another unit.

An object of the invention is to provide an improved method and means of refrigerating or of maintaining in a substantially constant refrigerated condition, perishable foodstufi's and the like so that the same may be stored or transported under the most desirable conditions and without deterioration due to changes in temperature or in moisture content.

Another object is to provide a method of both precooling and refrigerating perishable products in transit by loading the productsinto an enclosure whose surfaces are composed of material having a low thermal drop therethrough and which surfaces are separated from an insulated wall to form a general air passage in which refrigerated air is circulated, passing some of the circulated air from the passage through the enclosure in one or more short circuit paths for one continuous period until the space or products therein are precooled, thereafter permanently terminating the circulation of the air in the short circuit path through the enclosure and in contact with the product while continuing the circulation of air within the general air passage and in contact with the exterior surfaces of the chamber to maintain the products at reduced temperature principally by thermal transfer through the surfaces of the enclosure.

Another object is to provide a method of both precooling and refrigerating perishable products in transit by loading the products into an enclosure whose surfaces are composed of material having a low thermal drop therethrough and which is open on one side, which enclosure is surrounded by an air duct in which refrigerated air is circulated, passing some of the circulated air through the interior of the enclosure in a short circuit path for one continuous period at the outset of the transit period to reduce the temperature of the space within the enclosure, thereafter permanently terminating the circulation of the air in the short circuit path through the enclosure for the remainder of the transit period while continuing the circulation of the cooled air exterior to the enclosure and across the open side thereof to maintain an envelope of cooled air in contact with the outer surfaces of the enclosure and partially in contact with the atmosphere within the enclosure across the open side thereof to maintain the products at reduced temperature principally by thermal transfer through the surfaces of the enclosure and by some interchange of air across the open side thereof.

Another object is to provide an improved refrigerator vehicle embodying a cargo chamber composed of material having a low thermal drop therethrough and which is open on one side and which is enveloped withan air duct in which refrigerated air may be circulated about the chamber, together with damper controlled openings in one of the chamber walls communicating with the circulated air in the duct.

Another object is to provide a unitary air conditioning unit adapted for use in a railway refrigerator car.

Another object is to provide in combination with a railway car and an air conditioning unit adapted for use therein, means for supporting the unit in such a manner trarlsporting perishable foodstuffs in which the foodstuffs 6. that the same may be readily placed in or removed from e car.

Another object is to provide in combination with a railway car, and an air conditioning unit for use therein, means for supporting the unit in the car in such a manner as to protect the unit from shock and injury resulting from movement and jolting of .the car.

Another object is to provide in combination with an air conditioning unit including an internal combustion engine and other parts forming the operating mechanism a protective hood, together with means for recirculating a portion of the heated air from the engine so as to maintain the engine and its associated parts in an operating condition during cold weather.

Another object is to provide an air conditioning unit which is capable of either refrigerating or of heating the space within an enclosure and which is controlled by means which are capable of automatically reversing the heat exchanging function of the unit in response to the condition of the enclosed space.

Another object is to provide in an air conditioning unit which includes an evaporator and a fan for circulating air over the evaporator, a casing surrounding the evaporator having a set of movable dampers between the fan and the evaporator for shutting off the flow of air during a defrosting operation.

Another object is to provide in combination with a mechanical air conditioning unit used to maintain a substantially constaht condition within an enclosed space,

;control means for controlling the operation of the unit pair of air conditioning units which are not normally under manual supervision, control means for controlling the operation of the units under a plurality of variable conditions which may arise during the absence of manual supervision.

A further object is to provide means for storing or may be refrigerated if necessary, or maintained at a substantially constant temperature and moisture content, which includes a railway car having an internal chamber which is insulated on all sides from the walls of the car and which is supported in spaced relation to several of the walls so as to form an air passage and an area of moisture transfer, together with means for cooling or heating the air to attain or maintain the desired temperature within the internal chamber, and means for autovon a side opposite of that shovm in Fig. 1;

Figs. 38 are detailed views of the car structure shown in Figs. 1 and 2;

Figs. 9-12 are sectional views of a modified form of refrigerator car;

Figs. 13 and 14 are detailed views of a damper control mechanism used in conjunction with the refrigerator car described in Figs. 9-12;

Figs. 15 and 16 are perspective views of a mechanical air conditioning unit used in conjunction with either of the refrigerator cars disclosed heretofore;

Fig. 17 is a schematic showing of the refrigerant fluid system incorporated in the air conditioning unit disclosed in Fig. 15;

Figs. 18-29 illustrate a structure which supports the air conditioning unit disclosed in Fig. 15 within either of the car structures heretofore disclosed;

Figs. 30A and 30B disclose a portion of a hood structure shown in Fig. 18;

Figs. 31-35 disclose a door operating mechanism and a locking device used in conjunction with either of the cars heretofore disclosed; I

Fig. 36 is a schematic diagram of a control system for controlling the operation of a pair of air conditioning units and auxiliary devices used in connection therewith;

Fig. ]37 is a schematic diagram on enlarged'scale .showanemone ing a portion of the. electrical system disclosed in Fig. 36;

Fig. 38 is a schematic diagram of a portion of. the

control system used in conjunction with the refrigerator car disclosed in Figs. 9-12 and the damper controls shown in Figs. 13 and 14; and,

Figs. 39-41 show a thermostatic control device used in conjunction with the control device schematically shown in Figs. 36 and 37.

Referring now to the several figures of the drawing, the invention will be described in detail. Referring first to Figs. l7, general reference numeral 50 designates a railway vehicle ordinarily referred to as a refrigerator car and used for the transportation of perishable foodstuffs and the like. The vehicle includes the conventional undercarriage designated at 51 in Figs. 4 and 7, which is supported on wheels for mobility on railroad tracks, as shown in Figs. 1 and 2. Reference numeral 52 designates a floor surface of the car and reference numeral 53 designates an outer top surface on which is mounted a catwalk 54.

Referring now to Fig. 3,

reference numerals

55, 56, 57 and 58 designate the outer lateral walls of the car. Cargo loading doors 59 and 61), Figs. 1 and 5, are mounted on each of the lateral central surfaces of the car for moving the cargo within the interior thereof.

As shown in Fig. 2, supported beneath the undercarriage 51 are a pair of fuel tanks 61 and 62. which are interconnected by a header 63. A conduit 64' extends to a fuel loading opening 65 and a fire-proof breather 66 is secured on thelateral side of the car and connected by a conduit 67 to tank 61 for safety purposes.

On either side of the car, and of which only one is shown in Fig. 2, is a vertically movable door 68 having therein a grill 69. The doors 68 are slidably movable in tracks '71 and 71 on the side of the car. A ladder portion "/2 which forms a part of the door structure 68 is telescopically movable with respect to a stationary ladder portion 73 to permit members of a train crew to climb up to a grill "/4 located on the top of the car and at one side of the catwalk 54. A crank 75 is provided for controlling the movement of doors 68 and also for locking the same in their closed positions, and this crank is adapted to be removably inserted into socket portions 76 on either side of the end 58- to operate the doors and their respective telescopic ladders.

Also mounted on the outer surface of the car on both sides thereof are a pair of control panels 77 and '78, as seen in Figs. 1 and 2.

Referring now to Figs. 3 and 4, is shown an interior cargo-carrying chamber designated by the general reference numeral 80. The chamber 80, as shown in Figs. 4 and 6, is insulated from the bottom wall 52 by three layers of thermal insulation 81 which are protected by longitudinally extending beams 82 and covered by a wooden floor 82a. The sides of chamber 80 are thermally insulated from the lateral sides of the car by a first layer of thermal insulation 83 which is protected by Z-bars 84 and interior to layer 83 is another layer of thermal insulation 85 which is protected by longitudinally extending beams 86, as shown in Fig. 4. Between the

layers

83, 85 is a layer of plywood 83a and on the inner side of layer 85 is a second layer of plywood 85a. The upper surface of the chamber 80 is protected from the top wall 53 by a very thick layer of thermal insulation 87 which is protected by a plurality of longitudinally extending members 88. It should be particularly noted that at all points the thermal insulation is permitted to maintain its original depth or thickness and is at no point compressed, thereby providing a relatively thick thermal wall on all of the interior sides of the car structure.

Referring further to these same figures, the side walls of the chamber 80 are composed of relatively thin sheet members 89 which arespaced from the inner insulating wall surface 85a by a plurality of vertically extending beams 90 so as to form air channels 91 between the outer surface of the wall 89 and the inner surface of the plywood layer 85a. At the end of the chamber 80 adjacent the end wall 56, seen in Fig. 3, panel 92 is separated from the plywood surface 85a by a plurality of beams 93 so as to form a plurality of relatively wide air channels 94.

At its opposite end from that just disclosed, chamber 80 is formed with a bay or compartment 95 which extends through to. the end. wal1 58. and is. thermallyinsulated from the outer walls of the car in the same manner as the remainder of the chamber. Panels 96 are positioned on either side of an opening 97 into the inner end of the bay and are spaced from the plywood layer a by beams 93 to form air channels 99. On either side of the bay are compartments 101 within each of which is mounted an air conditioning unit indicated by the general reference numerals A and 16118 and which will be discussed in detail hereinafter.

Referring now to Figs. 1, 3, 4 and 6, the bottom floor of chamber 30 is composed of a plurality of panels designated at 102, each of which is mounted on a side beam 1113 by hinges 103a, as shown in Fig. 4, to be elevated when desired. The floor panels 102 are each composed of a layer of wood 104 on which are mounted a plurality of laths 105 to permit air circulation about the cargo. Beneath each of the panels 1192 are several longitudinally extending stringers 106 each of which has several cut-out portions 106a, as shown in Fig. 6. Secured to the lower extremities of the stringers 106 and as shown in detail in Fig. 3, is a moisture containing and transferring means in the form of a layer of felt 107 which is covered by a metal screen 108 on its upper surface, and a layer of canvas 109 on its lower surface. As shown in Fig. 8, the moisture absorbing means and particularly the layers of felt 167 which are individually attached to each of the panels W2 are of progressively decreasing thickness as they extend from the end wall 56 towards the end wall 53 of the car. A metal pan 110 having a flat lower surface and upstanding edges is formed as a part of the car underneath the moisture absorbing means and supported on the floor surface 82a, as seen in Fig. 4. The pan itself extends from the end wall 56 to the end wall 58 and is shaped to conform to the structure of the bay 95. As indicated in dotted lines at 111 in Fig. 3, a central plug type drain is provided with a plug 112 for draining and/or washing out the pan 110 when such action is desired.

The top wall of chamber 81), as shown in Fig. 4, consists of a panel 115 which is secured on the lower surface of insulation 87 and extends over the entire top of the chamber. However, it should be noted that the top wall panel 115 is spaced upwardly from the upper extremity of the

side walls

89, 92 and 96 so as to form an opening designated at 116 which is in communication with the

several air channels

91, 94, and 99 formed on the lateral walls of the chamber.

As shown in Fig. 4, between the end panels 96, and forming a closure for opening 97 is a central panel 117 which completely separates the main chamber 80 from the interior of the bay 95'. At its upper extremity panel 117 carries a grill 118.

As seen in Figs. 3, 4, 8, Within the interior of bay 95 is afloor surface 119 which is elevated above the surface of panels 102. Floor 119 has a first opening 120, Fig. 4, and in rear of opening 120 are a pair of openings 121' beneath each of the units 1110A, 1110B, one of which is seen in Fig. 8. As shown in Fig. 8, a plurality of baffles122 and123 are mounted on the undersurface of floor 119. At the extreme right, the metal pan 110, mentioned heretofore, terminates in a curved surface designated at 124. Mounted on floor 119 over the opening. 120 is an electric fan 125 of more or less conventional construction.

As will be evident'in Figs. 7 and 8, the side walls of the bay 95 extend up to the undersurface of the top wall 115 so that bay 95 may, with the exception of the grill 118-be considered as being a passage separated from the chamber 80. As shown in Figs. 3 and 7, each of the side walls of the bay 95 are provided with an enlarged opening 126 which openings are surrounded by a casement 127. On the outer surface of casement 127 is a heavy rubber gasket 123 which is intended to provide a resilient seal with a portion of the air conditioning mechanisms 100 and prevent the entry of outside air into the bay 95.

Referring now to Figs. 9, l0 and ll, is partially shown a modified form of car structure designated by the general reference numeral 130 and from which most of the exterior structure has been eliminated inasmuch as the same is substantially similar to that heretofore described in conjunction with the car structure shown by general reference numeral 50. Reference numeral 131 designates a. cargo-containing chamber having a bay portion 132v at: one end. thereof. Chamber 131 is insulated on