BACKGROUND OF THE INVENTION
In the transporting or shipment of temperature sensitive materials or items such as blood, plasma, vaccines and certain drugs, it is known to use insulated containers which include heating and/or cooling means as disclosed, for example in U.S. Pat. No. 5,483,799 and No. 5,603,220 and in U.S. Pat. No. 5,950,450 and No. 5,943,876 assigned to the assignee of the present invention and the disclosures of which are herein incorporated by reference. When it is desirable to transport or ship a larger volume of temperature sensitive items, it is desirable to provide a cargo container which is adapted to receive a pallet supporting the temperature sensitive items and which also includes cooling and/or heating means for maintaining the temperature sensitive items within a close predetermined temperature range. Such cargo containers are disclosed, for example, in U.S. Pat. No. 5,187,947, No. 6,860,115 and in a publication of applicants entitled AcuTemp™ Thermal Pallet Shipper. A Temperature-Controlled, Pallet-Sized Shipping Container is also disclosed in U.S. patent application No. 2004/0226309, published Nov. 18, 2004, and the disclosure of which is herein incorporated by reference. This published application claims the benefit of provisional application No. 60/447,987 filed Feb. 17, 2003 by four co-inventors including co-inventors of the present invention, and the disclosure of which is herein incorporated by reference.
In any such cargo container adapted to receive one or more pallets of temperature sensitive items, it is highly desirable for the container to have all walls and the doors with high thermal insulation or R value while minimizing the thickness of the walls in order to maximize the cargo space and minimize heat transfer to and from the container chamber. It is also desirable to provide efficient construction and assembly of the cargo container while providing substantial durability so that the cargo container has an extended service life. It is further desirable for temperature controlled air to be properly circulated within the cargo chamber in order to obtain a uniform temperature throughout the chamber. Preferably, the circulating air passes upwardly through a refrigeration evaporator and electrical heating elements and circulates along the walls of the container for precisely controlling the temperature within the cargo chamber.
In order for a cargo chamber to hold a narrow predetermined temperature range for an extended period of time, for example, over 72 hours, without an external power supply, it is necessary for the cargo container to carry storage batteries which may operate a refrigeration compressor or an electrical heating element through a control system which senses the temperature within the cargo chamber at predetermined locations. The heating element for the circulating air is sometimes desirable when the cargo container is being transported in a cold temperature zone or by an aircraft flying at a high altitude, and the container is exposed to very cold environmental air.
SUMMARY OF THE INVENTION
The present invention is directed to an improved cargo container assembly which provides all of the desirable features mentioned above including high thermal insulation with a relatively thin wall construction. The container may also be efficiently produced and provides substantial durability and a high strength/weight ratio so that the container may be conveniently handled by forklift trucks without losing its high thermal insulation against heat transfer into and out of the container chamber which receives the cargo or items to be transported.
In accordance with one embodiment of the invention, a cargo container generally includes a rigid outer housing which may be a sheet aluminum shell or can having opposite side walls connected by a bottom wall, a rear wall and a removable top wall, and with a front or side opening normally closed by hinged door assemblies. When the top wall of the housing is removed, the housing receives a sub-assembly which includes a box-like molded composite outer shell having a front opening and enclosing a box-like molded composite inner shell also having a front opening. The corresponding side, top, bottom and rear walls of the inner and outer shells confine therebetween flat panel insulation cartridges or cassettes. Each cassette includes two or more layers of vacuum insulation panels which may be separated by a foam insulation sheet and sandwiched between protective plastic sheets, all of which are wrapped within a plastic film.
A wall of the inner shell supports a refrigeration evaporator, an electrical heating element and circulating fans, all protected by a composite inner wall panel which provides for air circulation within the cargo chamber through the evaporator and heating element. The corresponding wall of the outer shell has a rectangular projection which supports a refrigeration compressor and storage batteries, and a control system senses the temperature within the chamber in different areas to operate the compressor and heating element from the batteries or an external power source in order to maintain a substantial constant preselected temperature within the chamber. A compartment of the housing encloses the compressor, storage batteries and control system which includes a plurality of smoke detectors for detecting smoke in the ambient air, and a plurality of ambient air temperature and humidity sensors, all for controlling the exhaust fans for the cargo container.
Other features and advantages of the invention will be apparent from the following description, the accompanying drawings and the appended claims.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view of a cargo container constructed in accordance with the invention and with the doors in their closed position;
FIG. 2 is a perspective view of the cargo container shown in FIG. 1 and with the doors shown in their open positions;
FIG. 3 is a vertical section through the cargo container, taken generally on the line 3-3 of FIG. 1;
FIG. 4 is a horizontal section of the container, taken generally on the line 4-4 of FIG. 3;
FIG. 5 is an exploded perspective view of a shell sub-assembly which is inserted into the outer housing assembly shown in FIG. 1 and which supports operating components;
FIG. 6 is an exploded perspective view of the shell sub-assembly before being inserted into the outer housing assembly;
FIG. 7 is an exploded perspective view of the door assemblies shown in FIGS. 1 and 2;
FIG. 8 is an exploded view of an insulation cartridge or cassette used in the walls of the shell sub-assembly and in the door assembly, as shown in FIGS. 5 and 7;
FIG. 9 is a cross-section of an assembled insulation cassette shown exploded in FIG. 8;
FIG. 10 is a fragmentary corner section of the top wall and door assembly of the cargo container, taken generally on the line 10-10 of FIG. 1;
FIG. 11 is a fragmentary section of the overlapping closed door assemblies, taken generally on the line 11-11 of FIG. 1;
FIG. 12 is a fragmentary corner section of the shell sub-assembly, taken generally on the line 12-12 of FIG. 6;
FIG. 13 is a fragmentary section of the shell sub-assembly, taken generally on the line 13-13 of FIG. 6;
FIG. 14 is a fragmentary section of the shell sub-assembly, taken generally on the line 14-14 of FIG. 6;
FIG. 15 is a fragmentary section of the shell sub-assembly, taken generally on the line 15-15 of FIG. 6;
FIG. 16 is a fragmentary corner section of the shell sub-assembly, taken generally on the line 16-16 of FIG. 6;
FIG. 17 is a rear perspective view of a modified cargo container with the rear wall enclosure and storage batteries removed; and
FIG. 18 is a block diagram of the electrical components and control system for the cargo container.
DESCRIPTION OF ONE EMBODIMENT
Referring to FIG. 1, a cargo container 25 includes an outer housing 28 which is formed of sheet aluminum and aluminum corner trim and sometimes referred to as a “can”. The housing 28 includes opposite side walls 32, a removable top wall 34, a rear wall enclosure 36 and a bottom wall 38 (FIG. 3). The housing 28 is supported by a set of hollow aluminum supports or legs 41 connected by an aluminum base plate 42, and the spaced legs 41 are arranged to allow a two or three way entry under the cargo housing 28 with a forklift truck. The transporting of the container 25 may be over the road (OTR) by trucks or rail or may be transported as a unit loading device (ULD) by a ship or aircraft. The housing 28 also supports a pair of swinging door units or assemblies 44 and 46 (FIGS. 1 & 2) each supported by a set of hinges 47 attached to the housing.
Referring to FIG. 6, before the top wall 34 of the housing is installed, the housing 28 receives a shell sub-assembly 50 which includes a molded composite box-like outer shell 54 (FIGS. 5 & 6) and a molded composite box-like inner shell 56, shown exploded in FIG. 5. Each of the shells 54 and 56 is molded as a one-piece unit, and the outer shell 54 includes a resin impregnated fiber reinforced outer skin 62 which forms opposite side walls 64 (FIG. 5) integrally connected by a top wall 66 and a bottom wall 68 (FIG. 5). The outer shell 54 also has an integrally molded rear wall 72, and support walls 74 project rearwardly from the rear wall 72 of the outer shell 54, and are also formed of fiber reinforced composite plastic material and may be formed integrally with the rear wall 72 of the outer shell 54.
The molded fiber reinforced side walls 64, rear wall 72, projecting support 74 and the bottom wall 68 are also molded with fiber reinforced panels 82 and 83 (FIG. 12) and 84 (FIG. 3) which provide substantial additional strength and impact resistance to the outer shell 54. Preferably, the fiber reinforced panels 82-84 are formed from fiber reinforced core panels produced as disclosed in U.S. Pat. No. 6,740,381, the disclosure of which is herein incorporated by reference. The molding of the composite outer shell 54 may be performed by vacuum assisted resin transfer molding (RTM) so that the resin penetrates the fibrous fabric forming the outer skin 62 of the shell 54 and also simultaneously penetrates the fibers within the fiber reinforced core panels 82-84 having inner skins and integral with the outer skin 62.
As mentioned above, the shell sub-assembly 50 also includes a composite box-like inner shell 56 (FIG. 5) which is molded in the same manner as the outer shell 54 and includes a one-piece fiber reinforced inner skin 92 (FIG. 5) which forms opposite side walls 94, a top wall 96, a rear wall 97 (FIGS. 4 & 5) and a bottom wall 98 (FIG. 12). All of the walls are integrally connected, and the rear wall 97 is provided with integrally molded co-planar step portions 102 (FIG. 4). The side walls 94 are molded with vertically spaced horizontal reinforcing ribs 106, and the lower portions of the side walls 94 and the bottom wall 98 are also molded with fiber reinforced core panels 108 and 110, respectively, which are resin impregnated with the inner skin 92 and formed in the same manner as the outer core panels 8284. The fiber reinforced core panels have a thickness of about ½ inch, and after the resin hardens, the reinforced panels provide the walls of the outer shell 54 and the lower portion of the inner shell 56 with substantial rigidity and impact strength, as described in above mentioned U.S. Pat. No. 6,740,381.
Referring to FIGS. 3 and 5, an aluminum or molded fiber reinforced partition or panel 114 has an open top and open bottom and is attached to the rear wall 97 of the inner shell 56 to define an upward flow air passage 116 adjacent the rear wall 97. A molded fiber reinforced flat panel 120 having a fiber reinforced core as described above, is attached to the step portions 102 of the rear panel 97 and cooperates with the side walls 94, top wall 96 and bottom wall 98 of the inner shell 56 to define a cargo receiving chamber 125. The volume of the chamber 125 may be on the order of 30 or 45 or 60 or 90 cubic feet, and is sufficiently large to receive a standard size pallet. The composite cold wall flat panel 120 is vertically reinforced, for example, by having vertical fibrous webs in the fiber reinforced core to provide the panel 120 with additional strength.
As shown in FIGS. 5 and 12, a series of laterally spaced channels 130 are molded as part of the bottom wall 98 or are attached to the bottom wall 98 of the inner shell 56 by adhesive 132, and the channels 130 support a substantially flat aluminum floor panel or plate 135 having a thickness of about ⅛ inch. The floor plate 135 (FIGS. 12 & 14) extends from the front opening of the inner shell 56 to the cold wall 120 to partition the inner cargo receiving chamber 125 from sub-floor air channels or passages 138. The sub-floor channels 130 extend from the front opening of the inner shell 56 to its rear wall 97, to create the air return passages 138 under floor plate 135 together with the inner shell floor 98 (FIG. 5). These passages connect the return air flow from the bottom front of the inner shell 56 to the upward flow air passage 116 (FIG. 3) for the evaporator/heater assembly. The sides of the floor plate 135 are provided with upwardly facing tie-down seat channels 139 (FIG. 4) for receiving straps or nets extending over the cargo. The forward edge portion of the floor plate 135 has a series of parallel spaced slots 142 (FIG. 4) which connect with the air flow passages 138. As shown in FIG. 3, the rearward ends of the passages 138 are open and provide for air flow from the passages upwardly into the chamber 116 defined by the panel 114.
Referring to FIGS. 5, 8 and 9, a set of flat panel thermal insulation cartridges or cassettes 145, 146, 147 and 148 are confined or sandwiched between the walls of the outer shell 54 and the inner shell 56. As shown in FIGS. 8 and 9, each of the insulation cassettes 145-148 includes a plurality of at least two panels or layers 152 each including a plurality of vacuum insulation panels 155. Each of the panels 155 is constructed substantially as disclosed in U.S. Pat. No. 6,623,413 assigned to the assignee of the present invention and the disclosure of which is herein incorporated by reference. As generally disclosed in the patent, each of the panels 155 includes a core of porous material enclosed within a bag of gas impermeable film. After the bag is evacuated, the bag is sealed to form a vacuum insulation panel as generally shown in FIG. 1 of the patent. Each of the layers 152 of vacuum insulation panels has a thickness of about ½ inch, and the layers are separated by a flat sheet 158 of plastic or expanded polystyrene foam and having a thickness of about ¼ inch. The layers 152 of vacuum insulation panels 155 are protected by and sandwiched between two outer sheets 162 of extruded plastic, for example, sold under the trademark “CoruPlast”. All of the assembled layers 152 and sheets 158 and 162 are wrapped with a flexible film 164 of fire retardant plastics material.
The thermal insulation panel assemblies 145-148 are illustrated in the partial section views of FIGS. 10-16 as a one-piece insulation panel for simplification, but it is to be understood that each of the panels 145-148 is constructed substantially as described above in connection with FIGS. 8 and 9. As shown in FIG. 16, a set of fiber reinforced ribs 170 are molded as an integral part of the inner shell 56 along the top and bottom and function as rigid spacers between the inner and outer shells. As also shown in FIGS. 5, 10 and 13-15, the inner fiber reinforced skin 42 of the inner shell 56 is molded with an outwardly projecting return flange portion 172 which extends around the front end of the inner shell 56 and has a U-shaped cross-sectional configuration as shown in FIGS. 10 and 13-15. As shown in FIGS. 12 & 16, the insulation cassettes 145 and 146 have partial insulation panel extensions which project into the corner spaces between the shells. Additionally, similar insulation extensions project into sections where closed cell PVC expanded foam has been removed to reduce the heat shunts. This facilitates the connection of the insulation cassettes to each other, improving overall insulation coverage and reducing heat leaks. Closed cell PVC expanded foam 174 fills the space between the return flange 172 and the front edges of the insulation panels 145-147 and may be used in other voids within the container 25.
As also shown in FIGS. 10 and 13-15, the return front flange 172 of the inner shell 56 is attached or bonded to the forward end skin portion of the outer shell 54 by strips 176 of adhesive. Also shown in FIG. 5, a rectangular trim frame 180 is molded of a plastics material such as ABS and has an L-shaped cross sectional configuration. The frame 180 defines the front opening for the cargo container chamber 125 and is attached or bonded to the fiber reinforced skin of the inner shell 56 by strips 184 and 186 of adhesive. The front end portions of the skin of the inner shell 56 may also be provided with interruptions to form thermal breaks for eliminating heat transfer through the skin.
Referring to FIG. 7, each of the door assemblies 44 and 46 includes an outer aluminum sheet or panel 196 secured to a rectangular tubular aluminum frame 198 to which the hinges 47 are secured. The inner surfaces of the door assemblies 44 and 46 are formed by panels 202 and 203, respectively, which are vacuum formed of a plastics material such as ABS and include an outwardly projecting peripheral flange 204 which is attached to the frame 198 of the door assembly by peripherally spaced screws or rivets. Each of the panels 202 and 203 is formed with parallel spaced vertical channels 206, and a series of expanded foam strips 208 are attached to the inner surface of the panel between the channels 206 to provide a flush surface. Each of the panels 202 and 203 also encloses an insulation cassette 210 which is constructed substantially the same as the construction of the insulation cassettes 145-148 described above in connection with FIGS. 8-9. That is, each of the insulation cassettes 210 includes two layers 212 of vacuum insulation panels 155 and the layers are separated by an expanded polystyrene foam sheet 214. Two panels 216 of expanded polystyrene foam are also located between the cassette 210 and the aluminum panel 196.
As shown in FIGS. 7 and 11, the left hand door assembly 46 includes an extension channel 220 which is vacuum formed from a sheet of plastics material such as ABS and is attached to the inner vacuum formed panel 202 of the door assembly. As shown in FIG. 11, the extension channel 220 overlaps a step portion 222 of the panel 203 of the right hand door assembly 44. The extension channel 220 is filled by a lateral extension 224 of the inner layer 152 of the vacuum insulation panels 155 of the corresponding insulation cassette 210. The cassettes cooperate with the foam boards 216 to provide substantial thermal insulation for the door assemblies 44 and 46. As shown in FIG. 4, the channels of the door panels 202 form air flow passages extending vertically directly above the slots 142 within the aluminum floor panel 135. As shown in FIG. 1, a releasable latch mechanism 225 connects the door assemblies.
Referring to FIGS. 3 and 4, the composite panel 114 between the rear wall 97 of the inner shell 56 and the cold wall panel 120, encloses an evaporator assembly 230 of a refrigeration system and also encloses an electrical heating coil or element 232. The impellers or fans of blowers 235 operate to pull the air upwardly within the channel 116 and pass the heating element 232 and through the evaporator assembly 230. Insulation strips 236 block air flow outside of passage 116. The blowers force the cooled or heated air through an opening or space at the top of the portion 120 and forwardly along the top wall 96 of the inner shell 56 and within the chamber 125 to the front door assemblies 44 and 46 where the air flows downwardly along the inner surfaces of the door panels 202 and then through the slots 142 within the floor panel 135. The air then flows rearwardly within the passages 138 below the floor panel and back into the bottom opening of the air flow passage 116. In this manner, air is continuously circulated around the payload or cargo within the chamber 125. In the event the cargo is tight against the inner surfaces of the door panels 202, the channels 206 provide air flow passages so that the air flow continues to flow downwardly along the door assemblies and into the slots 142 within the floor panel. In a preferred embodiment, a low power fan may be used to stir the air in the chamber when the main blowers 235 are not operating.
Referring again to FIGS. 3 and 4, the upper wall of the rectangular rear projection or extension 74 molded as an integral part of the composite outer shell 54 supports a motor driven refrigeration compressor 240 and condenser 242 having a housing supporting fans 244. The compressor and condenser are connected to the evaporator 230 by lines (not shown) extending through aligned holes within the rear wall 72 of the outer shell 54, the insulation cassette 148 and the rear wall 97 of the inner shell 56. The bottom wall of the extension 74 supports rechargeable storage batteries 250 which provide an output of 12 or 24 volts DC to operate the refrigeration compressor 240, the heater element 232 and the blower fans 235. Tie down straps 252 and bolts 253 secure the batteries positively to the bottom wall of the extension 74 of the outer shell 54.
As shown in FIG. 3, a set of upper and lower rectangular air vents 256 are provided in the rear compartment or extension 36 of the outer housing 28 to provide convection ventilation within the housing portion. As shown in FIGS. 1 and 2, a side wall of the housing extension 36 supports an exposed door covered control panel 260 of a controller 262 (FIG. 4), and the housing extension 36 also encloses a battery charger 264 and a dual voltage power supply connector 266 for the battery charger for receiving an external power supply of 110 volts or 240 volts AC. The control panel also encloses a universal AC voltage (100-240 VAC, 46-63 Hz) battery charger connector and a 12-28 V external DC power connector. The battery charger 264 is mounted on the side wall of the rectangular projection 74 and is connected to the universal AC voltage connector. The motor driven compressor 240 is mounted on the upper wall of the rectangular projection 74 and is connected to the internal and external DC power source through the controller 262.
FIG. 17 is a rear view of a modified cargo container 25′ which is constructed substantially as described above for the cargo container 25. In this modification, an elongated fiber reinforced box-like support 74′ is attached or bonded to the rear wall 72 of the outer shell 54 and is enclosed by a removable rear panel 276. A set of three exhaust fans 244 are supported by the closure panel 276 and are aligned with the upper air vent 256 in the rear wall enclosure 36. Another box-like support 280 is also attached or bonded to the rear wall 72 of the outer shell 54 and is also constructed from fiber reinforced composite panels, as disclosed in above-mentioned U.S. Pat. No. 6,740,381. The support 280 has an open top and is opened at the rear for receiving and supporting the storage batteries 250. The support 74′ and the rear wall 72 of the outer shell 54 also support a plurality of four commercially available smoke detectors 285 each of which is capable of detecting smoke in the ambient air surrounding the cargo container 25′ and within the rear wall enclosure 36. As shown in FIG. 18, the detectors 285 are connected to the controller 262 along with a plurality of four temperature and relative humidity sensors 290 which are located to sense the ambient air outboard of the cargo container.
The operation of the refrigeration compressor 240, the exhaust fans 244, the heating element 232 and the internal air circulating blowers 235 is controlled from the controller 262. A set of temperature sensing thermistors 272 (FIG. 3) are located in each of the eight corners of the cargo chamber 125 and at the front center of the floor panel 135 and are also connected to the controller 262. A more detailed description of the operation and control of the heating and cooling system is set forth in above mentioned published U.S. patent application No. 2004/0226309, the disclosure of which is incorporated herein by reference.
The operation of the exhaust fans 244 is also controlled by the smoke detectors 285 and the temperature and relative humidity sensors 290 through the controller 262. That is, in the event any one of the smoke detectors 285 detects smoke, the exhaust fans are shut down until the controller 262 is manually reset so that there is no air flow through the air vents 56 and no air exchange between the cargo container and the ambient air surrounding the container. In the event that the temperature and humidity sensors 290 detect that the ambient temperature surrounding the cargo container is too low or the relative humidity is too high, the controller 262 will also shut down the exhaust fans 244. When the ambient temperature and/or the humidity return to the preselected ranges, the controller 262 automatically restarts the exhaust fans 244. Thus, when the cargo container is used within the cargo area of an aircraft, the control system assures that there is no interference by the cargo container with the aircraft heat and smoke detection system.
From the drawings and the above description, it is apparent that a cargo container constructed and assembled in accordance with the invention provides desirable features and advantages. For example, the construction of the cargo container 25 or 25′ with the resin impregnated fiber reinforced walls of the outer shell 54 and inner shell 56 with the thermal insulation cassettes 145-148 confined between the composite walls provides a very desirable high insulation value, for example, an R value of over 50. As a result, temperature sensitive cargo may be maintained at a substantially constant temperature for an extended period of time with minimum energy consumption from the batteries 250 to operate the refrigeration compressor 240 or the electrical heating element 232. For example, if a temperature in the cargo chamber 125 is selected between plus 2° C. and plus 25° C., it is possible to maintain the temperature within plus or minus 1° C. for up to 72 hours without using an external power source. This permits temperature sensitive cargo to be delivered practically anywhere in the world by aircraft while maintaining a substantially constant temperature. Furthermore, the fiber reinforced composite walls of the inner and outer shells and the fiber reinforced core panels within the walls provide substantial impact protection for the vacuum insulated panels 155 while minimizing the weight of the wall panels. It is also within the scope of the invention to increase the thickness and strength of the fiber reinforced wall panels of the outer shell and eliminate the outer aluminum can or housing 28 so that the outer shell forms the outer housing, thereby reducing the overall weight and production cost of the cargo container.
Another advantage is provided by the construction and assembly of the thermal insulation cartridges or cassettes 145-148 and 210 with the joints of the vacuum insulation panels 155 on one side of the separation sheet 158 being offset and crossing the joints of the thermal insulation panels 155 on the opposite side of the sheet 158. As a result, the transfer of heat between the vacuum insulation panels is minimized or substantially eliminated, thereby further increasing the resistance to heat transfer through the wall panels. The circulation of the air within the cargo chamber 125 also helps to maintain a substantially constant temperature within the chamber. For example, cold air produced by the evaporator 230 is forced forwardly by the blowers 235 along the top wall 96 of the inner shell 56 and downwardly along the inside surface of the front door assemblies, through the slots 142 and then rearwardly within the passages 138 between the floor channels 130 and under the floor plate 135 for return to the lower open end of the evaporator panel 114. As mentioned above, the channels 206 within the inner door panels 202 assure that the downward flow of air cannot be blocked by cargo items within the chamber 125.
Further advantages are provided by the use of the smoke detectors 285 and the temperature and relative humidity sensors 290 to control the operation of the exhaust fans 244. This control system prevents the cargo container from interfering with any smoke detection system in an aircraft transporting the cargo container, and the sensors 290 cooperate to maintain the desired range of temperature in the cargo container chamber 125.
While the method of construction and form of cargo container herein described constitute desirable embodiments of the invention, it is to be understood that the invention is not limited to the precise method and form of container described, and that changes may be made therein without departing from the scope and spirit of the invention as defined in the appended claims.
Patent Application
20070289976
