US1980070A - Refrigerator container - Google Patents

Description

NOV. 6, 11.934. w 1 MADDEN 1,980,070

REFRGERAToR CONTAINER Filed July 1o, 1955 4 shets-sheet 1 HNNQS( Wg# Y W1 TNESSES:

IN VEN TOR. William .T Mmln NOV. 6, 1934. W, 1 MADDEN 1,980,070

REFRIGERATOR CONTAINER Filed July l0, 1933 4 Sheets-Sheet 2 IN VEN TOR: William l Mami/w,

v TToRNEYs.

Nov. 6v, 1934.

W. .1. MADDr-:N 11,980,079

REFRIGERATOR CONTAINER Filed July lO, 1955 4 Sheets-Sheet 4 l N VEN TOR William l mldn,

TTORNEYS.

Patented Nov. 6, 1934 UNITED STATE FFICE.

REFRIGERATQR CONTAINER Application .my 10, 1933, serial N6. 679,746

27 Claims.

My invention relates generally to refrigerator containers wherein solid carbon dioxide is used as the refrigerant medium, and more particularly to railway refrigerator containers ofa type and size comparable to less-than-carloadlot shipping containers such as are now used by railroads for the transportation of package freight on flat cars or other suitable vehicles. 'I'he object of my invention, generally stated, is to provide a refrigerator container, utilizing carbon dioxide as the refrigerant, which is designed to produce uniform and eicient refrigeration over a comparatively long period of time, whereby perishable products may be transported for long distances Without danger of deterioration, and Without the necessity of recharging the container en route.

One of the problems involved in maintaining a uniform temperature in containers of this character, throughout all portions of the lading, arises from the tendency of air to stratify by reason of the lack of positive air circulation. Ordinarily there is no source of energy available to create circulation by mechanical means other than the refrigerant itself.- My invention overcomes the diiculty of providing positive air circulation: first, by establishing'a definite circulatory system in indirect Contact with the refrigerant, wherein cold air flows down from a refrigerant bunker at the top of the container through a central air trunk, and then outward to the walls and upward around the `lading to the bunker again Where it is recooled; secondly by providing an exposed or poorly insulated section of the outer casing adjacent to the air circulating passage through which heat from the atmosphere is applied to the column of air as it rises along the side walls of the container, thus promoting circulation and causing the lading to be uniformly refrigerated; and thirdly by the provision of means for varying the area of the exposed section to Iregulate the rate of circulation.

Another object' of the invention is to provide means for automatically controlling the volume of air moving in the circulatory system of such a, container, whereby the temperature of the lading may be held within close limits and the refrigerant may be used economically and to best advantage. lected for thus controlling the circulation of air within the container are especially useful in that they establish, when the system is closed, dead air spaces in series effectively insulating 'I'he particular means se- (Cl. (i2-91.5)

the cold air chamber from the remainder of the air circulating passages.

Another object of the invention is to provide means for compensating for leakage around the door of the container, and to this end I employ a duct which carries oi the gases of sublimation from the refrigerant bunker, and which has heat conducting surfaces disposed adjacent to the door edges.

Another object of the invention is to providemeans for Ventilating the container Whereby it may be used either as a refrigerator or as a ventilated compartment, depending upon the type of lading to be carried and atmospheric conditions.

Still other and more specific objects and advantages characteristic of the refrigerator container of my invention will become apparent from the description hereinafter set forth of one embodiment or example thereof, the description having reference to the accompanying drawings."v Of the drawings: i

Fig. I represents a`top plan view of a railway refrigerator container embodying my invention, with a portion thereof shown in horizontal cross-section as indicated by the lines I-I of Fig. II.

Fig. II represents a Vertical cross section of the container taken centrally thereof as indicated by the lines I.I,II of Fig. I.

Fig. III represents al front elevation at the door side of the container, with a portion of the front-wall broken away to show the damper control mechanism.

Fig. IV represents an enlarged cross section of a side wall of the container, taken as indicated by the lines IVIV of Fig. II.

Fig. V represents an enlarged Vertical crosssection similar to Fig. II, but showing one top corner of the container in detail.

Fig. VI represents a cross-section of the container, taken as indicated by the lines VI-VI of Fig. V.

Fig. VII represents a fragmentary perspective view of a bottom corner of the container showing one of the louvers associated therewith.

Fig. VIII represents a perspective view of a louver casing.

Fig. IX represents a perspective view of a louver shutter; and,

Fig. X representsdiagrammatically the arrangement of damper controls of the container.

the drawings there is shown a container which, in its exterior dimensions and form, corresponds closely to merchandise containers such 110 A ployed for as are transported on railway cars, trucks, or the like, and are generally arranged end to end in a row, occupying the full platform space of the vehicle. The container comprises generally an outer metal casing. 1, lined with insulating material 2, and an inner shell 3 spaced inwardly therefrom to afford air circulating passages surrounding the lading to be refrigerated.

The outer casing 1, in the form selected for illustration, is reinforced inwardly and outwardly with stiffening members 4 and is provided with lifting hooks 5 at its top corners, whereby it lmay be connected to an overhead hoist for the purpose of shifting it fromcar to truck, from car to stationary platform, or'vice versa. While various materials may be emthe insulating lining 2 of the outer casing 1, I prefer to utilize the substance known as dry zero", and to maintain the lining in place by means of an inner metal casing 6. At the base of the container layers '1 of insulating material, such as kapok or cork, may be provided. The floor 8 upon which the lading is supported is spaced vertically above the insulating base material 7 by means of transversely extending beams 9. At the sides and ends of the container, the inner shell 3 is spaced inwardly from the casing 6 by means of vertically disposed members 10 which may take the form of Z-bars or channel bars. Between the inner shell 3 and the casing 6 vertical air passages 11 are thus dened. v

Preferably the inner shell 3, including the oor 8 upon which the lading is supported, is made of fir blocks jointed together. Perforations 15, 15a, are well distributed over the top of the inner shell 3 as well as throughout the oor 8. The sides and ends of the inner shell 3 are imperforate.- Within the lading space of the container, racks 16 of lattice construction may be provided for the purpose of protecting the inner shell 3 against damage due to impact with the lading. The racks 16 are shown as extending completely around the side and end walls, with the exception of the space where the hinged door 17 is located.

At the top of the container, and preferably centrally thereof, there is provided a bunker, comprehensively designated at 18, which is adapted to accommodate blocks of solid carbon dioxide. The refrigerant bunker 18 is suspended from the inner casing 6 of the container by means of metal strips 19, and at its sides and ends it is insulated by outer layers 20 of r and inner layers 21 of cork. Across the base of the refrigerator bunker there is a perforated aluminum plate 22 which serves as the support for the cakes of solid carbon dioxide. Spaced beneath the plate 22 there is an 'additional plate 23 which has depending therefrom a series of vertically disposed aluminum fins 24 affording a large heat conducting surface for the absorption of heat from the air below. The spaces formed between the plates 22 and 23, accessible through the perforations 22a, serve as pockets, which become filled with dead `or noncirculating gas evolved from Athe solid carbon dioxide, and they establish the desired thermal insulation between the refrigerant and the aluminum ns 24.

Immediately above the refrigerant bunker 18 there is provided a filling hatch 25 normally closed by an insulated plug 26 and tted with a hinged cover 27.` In order to facilitate the operation of charging the refrigerant bunker with cakes of solid carbon dioxide, I provide at Verably provided with radiating surfaces 35 which `the top of the container near the door-equipped wall, a level platformn 28. The cover 27 for the hatch 25 is hinged at the side opposite to the platform 28. Accordingly, a man can stand with ease at the top of the container and operate the dogs 29 which secure the hinged cover 27, and gain access to the interior of the bunker 18.

The base of the refrigerant bunker 18, together with the inner shell 3, forms a cold air chamber 30 into which the aluminum ns 24 project. From the cold air chamber 30 there extends vertically downward a central cold air trunk 31 which passes through the lading space and the floor 8 and joins with the air passage 32 beneath the floor. At the side and end walls of the container the spaces defined between the inner shell 3 and the surrounding casing 6 afford air passages l1 within which the relatively warm air may rise to the top of the container. Likewise at the vtop of the container the spaces defined between the inner shell 3 and the top of the casing 6 afford air passages 33 through which relatively warm air fromthe sides and ends of the container passes toward the refrigerant bunker 18. Additional vertical air passages 34 connect the horizontal air passages 33 with the cold air chamber 30. It will thus be observed that there is provided a definite circulatory air system in indirect contact with the refrigerant, which system completely surf rounds thelading to be refrigerated and is divided by the central of circuits through which air may take a relatively short path in its` travel from the refrigerant bunker 18 to the base of the container,

and thence outward to the side and end walls 'and upward, and thence inward to the cold air chamber 30. By reason of ythe perforations 15, 15a provided at the top and bottom of the lading space, a portion of the air circulating in the container will nd its way into the lading space and travel vertically upward through the lading.

From the refrigerant bunker 18 a gas duct 36, serving as the discharge pipe for the evolved l gases of sublimation in the bunker, extends outward horizontally toward the door-equipped wall of the container. Throughout its horizontal portion the gas duct 36 is covered with insulating tape 36a. tends vertically downward to the top edge of the door 1'7 where it forms two branches 37, 38 leading in opposite directions across the top edge of the door. The branches 37, 38 are prefmay take the form of laterally projecting fins. One such branch 37 of the gas duct 36 leads vertically downward along the hinged edge of the door, and the other branch 38 leads vertically downward along the free edge of the g door. At-the base of the container and centrally beneath the door, the duct branches 37, 38 join together at a pipe 39 which discharges the gas downward through the outer casing 1. The gas duct 36 and its branches 37, 38 thus 3 serve to absorb heat from air leaking into the container at the door joints, and because they completely envelop the door and afford relatively large heat conducting surfaces they adequately compensate for such leakage. i It will be observed, as most clearly shown in Fig. I, that the perforations 15 at the top of the inner shell 3, and the corresponding perforations in the floor member 8 are more widely spaced in the regions near the air trunk 311 air trunk 31 into a plurality The gas duct 36 then ex- 1i the damper 41.

than at the 'regions near* the walls and door of the container. 'Ihe spacing of the perforations 15 from each other and from the central air trunk 31 is such as to insure uniform tempera-- ture in the lading space. Moreover, immediately adjacent to the door opening there is a row of perforations 15al in the top member of the inner shell 3,'and there is a corresponding row of perforations 15a in the oor member 8. Hence a certain portion of air will rise from the bottom to the top of the container behind the door opening compensating forV the absence of a conned air passage inithe region behind the door.

To control the circulation of air within the circulatory system which surrounds the lading, a set of dampers 40a, 40h is provided in the air passages 34 and an additional damper 41 is provided in' the central air trunk 31. The dampers 40a, 4Gb are arranged in pairsat each side of the refrigerant bunker 18 with the dampers of each pair spaced apart so thatA when closed they establish a relatively large dead air space 42 between them. Furthermore, each damper 40a, 40h is preferably constructed of two bafe plates separated to afford an air space between them. The dampers 40a, 40h of each pair are interconnected for simultaneous opening andclosing. When closed 'it will be noted that they establish dead air spaces in series insulating the cold air chamber 30 from the adjacent air passages 33.

.The large damper 41 located in the central cold air trunk 31 is likewise constructed of parallel baille plates 45 separated to aord between them a dead air space 46. As shown in Fig. III, the damper 41 is mountedon an actuating shaft 48 which extendshorizon'tally outward from the center of the container and terminates within the air passage 32 at one of the side walls. Likewise the dampers 46a, 40h have actuating shafts 49a, 49h, which terminate in the last mentioned air passage 32.

The apparatus for operating the dampers 40a, 40h, as well as the damper 41 is most clearly shown in Fig. X, where it is represented diagrammaticallyv for clearness of illustration. It will be observed that all of the dampers are interconnected for simultaneous opening-and closing, and that their movement is controlled by a thermostatA which is represented at 50 and is desirably of the sylphon type. The sylphon 50 includes a movable arm 51, the angular movement of which is governed by changes of temperature in the air passages 11` where the sylphon is located? To the movable arm 51 of the sylphon 50 there is attached a cable 52 which leads to an arm 53 on the actuating shaft 48 of To the arm 53, which operates ythe cold air damper, there are attached two cables 54, 55. The cable 55 passes-over a sheave 56a, and an additional sheave 57a, and joins parallel arms.58a xed to the actuating shafts 49a of the pair of dampers 40ct.t Thence the cable 55 joins the end of a counter weight 60a which is suspended freely within the air passages 11. The other damper control cable 54 passes over a sheave 56h in the opposite direction and then over an additional sheave 57h Where it `joins parallel arms 58h fixed to thev actuating three rows of ports 62.

perature changes in the Warm air passages 11 at the sides of the container in the following manner. When the lading is at the desired temperature, the arm 51 ,of the sylphon 50 is in the raised position under the influence of the counter weights 60a, 60h, and the dampers 40a, 4Gb, 41 are all closed, shutting off the movement of air in the circulatory system which surrounds the lading. Upon an increase in temperature above the desired point, the sylphon 50 will cause the' arm 51 to be lowered against the tension of the cables 52, 54, 55, simultaneously swinging the arms-53, 58a, 58h, and opening all of the dampers 41, 40a, 4Gb, to corresponding positions depending upon the temperature of the air in the circulatory system. When the temperature has been lowered to the desired point by reason of the circulation of cold air, the sylphon 50 will cause the arm 51 to be raised, and the weights 60a, 60h will return the arms 53, 58d., 58h to their original positions, closing all of the dampers 41, 40a, 40h.

In order to promote circulation within the air passages which surround the lading, the container of my invention has sections of its exterior casing l poorly insulated, as shown in Fig. IV, near the base thereof, thereby exposing portions of the circulatory air system to heat from the atmosphere. The difference in temperature between the air at the base of the container and at the top of the container induces the desired circulation. In the particular example selected for illustration, the container is provided with 61 is constructed in the form of a box made 0f one or more pieces of insulating material and is slotted at the outside and inside to afford there are three shutters l63 arranged in tiers. Each shutter 63, as shown in Fig. IX, is in the form of a conduit of substantially square cross section, and has in its front and rear walls ports 64 which are adapted to registerwith the ports 62 of the louver casing. Each shutter 63 is closed at both ends. The shutters 63 are adapted to slide within limits in the louver casing 6l and are moved back and forth by means of handles 66, the handles being accessible from the outside of the container. At the rear of each louver casing 61, as shown in Fig. IV, there is a slab 67 of insulating material of reduced thickness as compared with the insulating' lining 2 thereabove. In an obvious manner by manipulation of the shutters 63, air from the atmosphere can be admitted to the space within the louvers 61 exposing the insulating slabs 67 throughout the whole or a fraction of their surface areas. When any one of the shutters 63 is in closed position, the dead air in the interior space thereof acts as insulation. Moreover, the slabs 6'? are preferably recessed at their outer sides, as indicated at 67a, to provide an a'dditional dead air space of the desired insulating quality effective when the shutters 63 are closed.

In order that the container may be ventilated, when it is not used for purposes of refrigeration, and when it is carrying a type of lading which requires ventilation, means are provided for admitting air from the atmosphere through the base of the container and allowing'it to discharge near the top of the container. For this purpose the insulating slabs 67 have hinges 68 Within each louver 61;

` As shown in Figs. VII and VIII, each louver ing the container the air is discharged through' ports 70, shown clearly in Figs. IV and VI, near the top of the container. Desirably there is a discharge port for each louver casing 61, the discharge ports being normally closed by plugs 71. To `gain access to a plug 71 an operator within the container opens a door 72 in the roof of the inner shell 3, the door swinging down on hinges 73. The operator then reaches upward into the air passage 33 and draws the plug 71 inwardly and then shifts it laterally into a rack 74. The plugs may be guarded against loss by means of chains or other obvious devices attached to the container which prevent them from being removed therefrom.

When the insulating slabs 67 are swung inwardly and downwardly and the plugs 71 are removed from the ports 70, air from the atmosphere is conducted to the circulatory system of the container and allowed to pass around the lading and to discharge near the top of the container. The degree of ventilation desired may be regulated by operation of the louver shutters For the purpose-of humidifying the air as it passes from the cold air chamber 30 down through the central air trunk 31, I preferably provide a series of spaced water trays within the air trunk. The water trays 80, as shown in Figs. II and III, are annular in shape with circular openings 81. They impart moisture to the air as it iiows from the coldest region of the container, the cold` air chamber 30, down through the central air trunk 31, the air passing through the circular openings 81 on its way to the base of the container. In order thaty each .Water tray 80 may be filled from the lading space of the container, there is associated with each tray a funnel 83 leading through the wall of the air trunk 31 and terminating in an enlarged mouth which is readily accessible to an operator lstanding in the lading space of the container. While the particular means for filling the trays 80 admit of great variation, I have selected for illustration the funnels 83, each provided with a measuring rod 87, including a han'- dle 84 and a' closure member 85 for sealing the opening at the mouth of the funnel. In an obvious manner `the operator may gauge the amount of water in the trays, and fill them as occasion demands.

The operation of the refrigerator container o,

my invention is as follows: Let it be assumed that the dampers 40a, 40h, l1 are closed, and that the lading is at the desired temperature. Let it also be assumed that certain of the louver shutters 63 are opened exposing relatively Warm air from the atmosphere to the insulating slabs 67 o'f reduced thickness. Under these conditions the air Within the container will be substantially motionless, and such heat as is admitted to the interior of the container will, for the most part, be absorbed by the gas duct 36 and its branches 37, 38. With the very gradual application of heat, the temperature of air within the container will rise to the point where the sylphon.

50 is set to operate. When in response to an increase in temperature the sylphon 50 causes swinging movement of -its arm 51, the dampers 40a, 40h, 41 will open simultaneously. Heat applied Aat the poorly insulated sections of the container casing 1 will then promote a denite circulation of air in the circulatory system of the container. Cold air will drop downward from the cold air chamber 30 through the central air duct 31 to the air passage 32 at the floor of the container where the air will divide, portions of it travellinghorizontally outward to the sides and en ds of the container, and another portion, say one-third of the total amount, or thereabouts, will pass upward through the perforations 15 into the lading space. The latter portion of Aair will find its way eventually through the perforations 15 at the top of the inner shell 3 and through the dampers 40a, 40h back to the cold air chamber 30. The major portion of the air from the bottom of the container will travel outwardly and upwardly through the air passages 11 to the top of the container, thence it will travel inwardly through the air passages 33, 34 and the dampers 40a, 40h lto the cold air chamber n It will be observed that the `air in its passage to and from the cold air chamber 30 divides itself into-a number of circuits and travels-in a relatively short path, the cold air flowing downward, and the warm air flowing upward, in accordance with the laws of nature. There is thus established a definite circulation with uniform refrigeration of theflading. 'It will also,

be observed that the cooled air does not rst come in contact with the lading at the top of the container, but must first pass downward through the imperforate central air trunk before it is applied to the lading. Thus the lading is not subjected to the very low temperature of the air in the cold air chamber 30 and is uniformly refrigerated from the bottom to the top.

When the temperature in the lading space has been reduced to the desired point, the sylphon 50 will operate to close'the dampers 40a, 4Gb, Ail, such closure being effected simultaneously. With the dampers closed, dead air spaces are established between the warm air ducts 34 and the cold air damper 4l, and between the cold air chamber 30 and the central duct 31, thus effectively insulating the cold air chamber from the circulatory system. Moreover, the dead air in the cold air chamber 30 itself acts as insulation, thermally insulating the lading space from the refrigerant.

' By means of the louvers 61 the rate of vcirculation of air in the vcirculatory system can be regulated to suit atmospheric conditions, and the type ei lading which is to be transported. Under certain conditions it may be found desirable to keep the louvers closed and under certain conditions it may be found desirable to keep them partially or fully open.

When the container is not used'for purposes of` refrigeration, and it is desired to ventilate la the lading, this can be accomplished by the simple acts of swinging the insulating slabs 67 inward, opening the shutters 63 of the louvers 61 and removing the plugs 71 at the top of the container.

While I have described my invention in some detail, and with reference to a specific embodiment or example thereof, it will be apparent,

especially to those skilled in the art, that various changes may be had in the former the container; and that certain features of the invention may at times be used to advantage without a corresponding use of other features, all without departing from the spirit of my invention as defined in the annexed claims.

Having thus described my invention, I claim:

1.v In a refrigerator container, anouter casing lined with insulating material, an inner shell enclosing the lading and defining with said casing a circulatory passage for air, and a bunker for solid carbon dioxide ldisposed within said outer casing in indirect contact with said air passage, portions of said air passage being.

thermally exposed through said outer casing tol the atmosphere to heat the air in said passage and promote its circulation.

2. In a refrigerator container, an outer casing lined with insulating material, Aan inner shell enclosing the lading and defining with said casing a circulatory passage for air, and a bunker for solid carbon dioxide disposed at the top of said outer casing in indirect contact with said air passage, said inner shell being perforated to permit a portion of the refrigerated air to circulate through the lading space, and portions of said air passage being thermally exposed through saidouter casing to the atmosphere to heat the air in said passage and promote its circulation. A l

3. In a refrigerator container, an outer casing lined with insulating material, a bunker for solid carbon dioxide refrigerant at the top of said casing, an inner shell enclosing thelading and. defining with the outer casing confined passages for air, said passages including a chamber directly beneath the bunker and in indirect contact with the refrigerant, and an air trunk extending downward from said chamber through vthe lading space to the base of said casing-and forming with the air passages aforesaid a continuous circulatory air system surrounding the lading, the la'ding space completely surrounding said air trunk. In a refrigerator container, an outer casing lined with insulating materiaL' a rbunker for solid carbon dioxide refrigerant disposed at the top of said casing, an inner shell en-A closing the lading and'defining with the outer casing confined passages for air, said passages including a chamber directly beneaththe bunker in direct contact with the refrigerant, and an air trunk extending downward from said chamber through the lading space to the base of said casing and forming with the air passages aforesaid a continuous circulatory system sur--v rounding the lading, the lading space completelyV surrounding said air trunk, and said inner shell being perforated to permit a portionof the airr in said system to circulate through the lad-l ing space.

5. In a refrigerator container, an outer cas-y ing lined with insulating material, a bunker for. solid carbon dioxide refrigerant at the top of said casing, an inner Ashell enclosing the lading and defining with the outer casing con` fined passages for air, said passages including a chamber beneath the bunker and being in indirect contact with the refrigerant, and an air trunk extending downward from said chamber through the lading space and forming with the air passages aforesaid a circulatory system" surrounding the lading, portions of said air passages being thermally exposed through said casing to the atmosphere to heat the air in said system and promote its circulation.

6. In a refrigerator container, an outer casing lined with insulating material, an inner shell enclosing the lading, said shell having a central air trunk extending vertically therethrough, and said shell defining with the outer casing vconfined passages which together with the central air trunk form a circulatory system surrounding the lading, a bunker for solid* carbon dioxide refrigerant disposed above said air trunk with the refrigerant in indirect 'Contact with the circulatory system, and portions of said air passages being thermally exposed through said casing to the atmosphere to heat the air in said system and promote its circulation.

7. In a refrigerator container, an outer casing lined with insulating material, an' inner shell enclosing the lading and defining with said casing passages for the. circulation of air, a bunker for solid carbon dioxide refrigerant disposed in proximity to said casing, a cold air chamber separating the bunker from the lading space and joining the air passages aforesaid at opposite sides of the bunker with the' refrigerant in indirect contact with said chamber, and dampers for controlling the circulation of air in said passages characterized by spaced bae plates disposed at the junctures between the air passages and the coldair chamber, said dampers when closed establishing `dead air spaces in` series around said bunker and insulating the air passages and the lading space from the bunker.

8. In a refrigerator container, 'an outer cas- .ing' lined with insulating material, a bunker for solid carbon dioxide 'refrigerant disposed at the top of said casing, an inner shell enclosing the lading and dening with said casing passages for the circulation of air around the lading,

said passages including a ,cold air chamber be' neath the bunker in indirect contact with the in y refrigerant, and a -plurality of interconnected -w' dampers disposed at opposite ends of said cold air chamber and characterized by spaced baic lplates for controlling the circulation of air in saidrpassages, said dampers when closed establishing dead air spaces in series insulating'the cold air chamber from the adjacent air passages, an'd forming additional insulation substantially surrounding the base of the refrigerant bunker and insulating it from the lading space.

9. In a refrigerator container, an outer cas` '3 ing lined with insulating material, a bunker for solid carbon dioxide refrigerant disposed at the top of said casing, an inner shell enclosing the lading and defining with said casing passages forv the circulation of air around the lading, said passages including a cold air chamber beneath the bunker, and a trunk extending downward from said chamber through the lading space and forming with the air passages a circulatory system, dampers disposed at opposite ends of said cold air chamber for controlling the admission of air fromthe air passages aforesaid to said cold air chamber, and an additional damper controlling the discharge of air from said chamber to said trunk, all of said dampers being interconnected for simultaneous opening and closing, and said dampers when closedforming a dead air space extending substanwie' 'Y passages including a cold air chamber beneath the bunker, a trunk extending downward from said chamber through the lading space and forming with the air passages a circulatory system, dampers disposed at opposite ends of said cold air chamber for controlling the admission of air from the air passages aforesaid to said cold air chamber, an additional damper controlling the discharge of air from said chamber to said trunk, all of said cally interconnected for simultaneous modulat7 ed opening and closing, and a thermostat functioning with .variations in the temperature of the air for operating said dampers.

11. In a refrigerator container, an outer casing lined with insulating material, a bunker for solid carbon dioxide refrigerant disposed at the top of said casing, an inner shell enclosing the lading and defining with said casing passages for the circulation of air around the lading, said passages including a cold air chamber beneath the bunker, a trunk extending downward from said chamber through the lading space and forming with the air passages a circulatory system, dampers disposed at opposite ends-of said cold air chamber for controlling the admission of air from the air passages to said cold air chamber, an additional damper controlling the discharge of air from said chamber to said trunk, said dampers being-mounted on actuating shafts extending into the air passage at one side of the casing, and said shafts being interconnected for simultaneous revolution, and a thermostat functioning with variations in Vthe temperature of the air for operating said dampers through said shafts.

12.' In a refrigerator container, an outer casing lined with insulating material, a bunker for solid carbon dioxide refrigerant disposed at the top of said casing, an inner shell enclosing the lading and defining with said casing passages for the circulation of air around the lading, said passages including a cold air chamber beneath the bunker, a trunk extending downward from .saidchamber through the lading space and formingwith the air passages a circulatory system, dampers controlling the admission of air to said cold air chamber, an additional damper controlling the discharge vof air from said chamber to said trunk, said dampers being mounted on actuating shafts extending into the air passages at one side of the casing, a weight influenced system of cables connecting said shafts for simultaneous revolution, and a thermostat functioning with Variations in the temperature of the .air for operating said cable system.

i3. In a refrigerator container, an outer casing lined with insulating material, a bunker for solid carbon dioxide refrigerant disposed at the top of said casing, an inner shell enclosing the lading and defining with said casing passages for the circulation of air around the lading, said passages including a cold air chamber beneath the bunker, and a trunk extending' downward from said chamber through the lading space and forming with the air passages a circulatory system, said trunk being completely surrounded by the lading space and having imperforate walls, and said'inner shell being perforated at the top and bottom of the casing whereby a portion of the air in said circulatory system passes from the base of the casing upward through the lading space.

le. in a refrigerator container, an outer oase dampers being mechani ing lined with insulating material, a bunker for solid carbon dioxide refrigerant disposed at the top of said casing, an inner shell enclosing the lading and defining with said casing passages for the circulation of vair around the lading, said passages including a cold air chamber beneath the bunker, and a trunk extending downward from said chamber through the lading space and forming with the air passages a circulatory system, said trunk having imperforate walls and said inner shell being perforated at the top and bottom of the casing whereby a portionA of the air in said circulatory system passes from the base of the casing upward through the lading space, portions of said air passages near the base of the casing being thermally exposed through said casing to the atmosphere to heat the air in said passages and promote its circulation.

15. In a refrigerator container, an outer casing lined with insulating material, an inner shell enclosing the lading and defining with said casing a circulatory passage for air, a bunker for solid carbon dioxide disposed within said outer casing in indirect contact with said air passage, portions of said air passage beingthermally exposed through said outer casing to the atmosphere to heat the air in said passage and promote its circulation, and means for varying the area of the exposed section of the casing.

16. In a refrigerator container, an outer casing lined with insulating material, an inner shell enclosing the lading and defining with said casing a circulatory passage for air, a bunker for solid carbon dioxide disposed within said outer casing in indirect contact with said air passage, portions of said air passage being thermally 'exposed through said outer casing to the atmosphere to heat the air insaid passage and promote its circulation, and insulated louvers hand operated from the outside of the casing for vari/' ing the area of the exposed section of the casing.

17. In a refrigerator container, an outer casing lined with insulating material, an inner shell en` closing the lading and defining with said casing a circulatory passage for air, a bunker for solid carbon dioxide disposed within said outer casing in indirect contact with said air passage, portions of the lining of insulating material of the outer casing being of reduced thickness and thermally exposedfthrough said outer casing to the atmosphere, thereby .to heat the air in said passage and promote its circulation.

18. In a refrigerator container, a doorequipped outer casing lined with insulating material, an inner shell enclosing the lading and defining with said casing a circulatory passage for air, a bunker for solid carbon dioxide disposed at the top of said casing and in indirect contact with said passage, and a duct for discharging the evolved gases of sublimation in said bunker, said duct leading downward around the edges of the door at the inside of the casing, and passing through said casing near the base thereof, said gas duct being adapted to absorb heat from air leaking into the casing at the door.

19. In a refrigerator container, a doorequipped outer casing lined with insulating material, an inner shell enclosing the lading iii Leader@ for air surrounding the lading space except for the area at the door opening, a bunker for solid carbon dioxide disposed at the top of said casing and in indirect contact with said air pasv sages, said inner shell having a row of perforations in the base thereof immediately' adjacent to the door opening and having a corresponding row of'perforations in the top thereof immediately adjacent to the door opening, and said perforations serving to eiect a curtain of air rising from the bottom to the top of the casing behind the door opening.

2l. In a refrigerator container, an outer casing lined with insulating material, a bunker for solid carbon dioxide refrigerant disposed at the top of said casing, an inner shell enclosing the lading and defining with the outer casing conned passages for air, said passages including a chamber directly beneath the bunker in indirect contact with the refrigerant, and an air trunk extending downward from said chamber through the lading space to the base of said casing and forming with the air passages aforesaid a circulatory system surrounding the lading, said inner shell being perforated at top and bottom and imperforate at the side Walls to permit a portion of the air in said system to circulate through the lading space and said perforations being more widely spaced in the regions near the air trunk than at the regions near the side walls to maintain 'a uniform temperature in the lading space.

. 22. In a refrigerator container, an outer casing lined with insulating material, a bunker forv imparting moisture to the air as it flows from I the chamber aforesaid to the lading space.

including a chamber directly beneath the bunker in indirect contact with the refrigerant, an air trunk extending downward from said chamber through the lading space to the base of said casing and forming with the air passages aforesaid a circulatory system surrounding and penetrating the lading space, a humidifier comprising spaced water trays disposed within said air trunk for imparting moisture to the air as it flows from the chamber aforesaid to the lading space, and means whereby said trays may be filled from within the lading space.

24, In a refrigerator container, an outer casing lined with insulating material, an. inner shell enclosing the lading and dening with said outer casing a circulatory passage for air, a bunker for solid carbon dioxide disposed within said outer casing in indirect contactwith said air passage, said outer casing and its insulated lining having openings at regions near the top and bottom thereof, and closure members normally lling said openings, said closure members being removable to permit ventilation of said circulatory passage with air from the outside atmosphere.

25. In a refrigerator container, an outer casing lined with insulating material, a perforated inner shell enclosing the lading space and dening with said outer casing a circulatory air system surrounding and penetrating the lading space, a bunker for solid carbon dioxide disposed within said outer casing in indirect contact with said circulatory system, said outer casing and its insulating lining having openings at regions near the top and bottom thereof, and t phere.

26. In a refrigerator container, an outer casing lined with insulating material, an inner shell enclosing the lading and dening with said outer casing a circulatory passage for air, a

bunker for solid carbon dioxide disposed within said outer casing in indirect contact with said air passage, said outer casing and its lining having an opening therethrough, and a closure member' of relatively poor insulating quality normally filling said opening but removable to L permit ventilation of said circulatory passage with air from the outside atmosphere, said closure member in its normal position serving to expose said circulatory passage to the atmosphere to'heat the air therein and promote its circulation.

27. In a refrigerator container, an outer casing. lined with insulating material, an inner shell enclosing the lading and defining with .said outer casing a circulatory passage for air,

a bunker for solid carbon dioxide disposed within said outer casing in indirect contact with said air passage, said outer casing and its 1ining having an opening therethrough, a closure member of relatively poor insulating quality normally filling said opening but removable to perl mit ventilation of said circulatory passage with air from the outside atmosphere, said closure member in its normal position serving to thermally expose said circulatory passage to 'the atmosphere to heat the air therein and promote its circulation, a louver at said opening in the casing, and insulated shutters movable across the openings in said louver.

. WILLIAM J. MADDEN.

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