Abstract:
A process with associated methods keeps the internal temperature of a cargo container within a temperature range during long transits having unpredictable high ambient temperatures. A cargo payload is shipped inside of an insulated container. The insulated container contains some form of refrigerant cooling agent (such as gel packs) to assist in keeping the internal temperature within the temperature range during transit. The container&#39;s shipping route to its destination includes stops at physical stations (hubs) where the container&#39;s internal temperature is measured using non-intrusive methods. If the internal temperature is above a trigger value, the container&#39;s refrigerant is replaced with new frozen ones. The container is shipped to the next hub or end destination. By exchanging refrigerant as needed, the container and its payload can traverse long distances over long time periods and still maintain its internal temperature within a desired window.

Description:
RELATED APPLICATION 
       [0001]    This application is a non-provisional of U.S. Ser. No. 61/736,298, filed Dec. 12, 2012. 
     
    
     FIELD OF THE INVENTION 
       [0002]    This invention relates to shipping systems, and more particularly to a method for maintaining a defined internal temperature range of a standalone, passive, shipping container over a long distance of transit. 
       BACKGROUND OF THE INVENTION 
       [0003]    Hot and cold sensitive products such as payloads of food, medicine, or liquid are often shipped using some sort of ambient-temperature insulating container. Common payload insulators include polyurethane and expanded polystyrene. There are passive and active (usually battery powered) methods to control the internal temperature. 
         [0004]    Insulation by itself may not keep the internal payload within a defined temperature range during transit when using passive containers. This is especially true when the shipped container experiences high ambient temperatures during a long passage. It is desired to maintain a container&#39;s internal payload temperature within a specified range over long distance travel using temperature management techniques along with passive packaging. 
         [0005]    Passive ambient-temperature insulted shipping containers have been in existence for many decades. In general, there are several categories of temperature insulation techniques to maintain internal temperature stability for standalone containers. Examples of these are: 
         [0006]    1. Ambient-temperature insulated container (such as a picnic cooler with walls of expanded polystyrene foam). 
         [0007]    2. Ambient-temperature insulated container with dry ice, refrigerated gel packs, or other phase change material (such as a picnic cooler with frozen gel packs). 
         [0008]    3. Ambient-temperature insulated container with active cooling and/or heating during transit. The internal temperature of the container is heated or cooled using energy from a battery supply or other internal or external energy source. An internal thermostat and controller maintain the container internal temperature. 
         [0009]    Each choice above has associated pros and cons in terms of maintaining internal temperature stability. For example, in order of the list above, 
         [0010]    1. Limited internal temperature stability when the ambient is very hot or cold. Even with three-inch thick insulated walls, the internal payload temperature may vary outside the desired range after only 8-12 hours of transit time. 
         [0011]    2. This offers improved internal temperature stability compared to 1. Typically, 48-72 hours of transit are common even with ambient temperatures occasionally peaking 40F above the internal target temperature. Beyond about 3 days in transit, this solution performs poorly especially with wide dynamic-ranging ambient temperatures. 
         [0012]    3. This method offers sustained internal temperature stability over long distance routes. The container requires an internal energy source and controller module to keep the payload within the desired temperature range. Solutions of this type are very expensive, heavy and large compared to methods 1 and 2. This is not practical for most shipping scenarios. 
         [0013]    There is currently no practical way to ship containers over long distances (3K-12K miles) with transit times of up to 9 days and still maintain the payload temperature within a desired range. Some carriers offer 2-3 day shipping, using refrigerated containers, from any point to any point worldwide, but the costs are prohibitively high for many uses and applications. 
         [0014]    What is desired is a shipping system that controls the temperature of a payload inside a shipping container. A passive shipping container that does not require an energy source to maintain temperature is desirable. A low-cost method to maintain a payload&#39;s temperature within a range despite long shipping distances and transit times is desired. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0015]      FIG. 1  shows a basic flow and process steps for passive temperature-controlled transit. 
           [0016]      FIG. 2  shows some components of one embodiment of a passive temperature-controlled shipping system. 
           [0017]      FIG. 3  shows a process flow of a temperature-controlled shipping system. 
       
    
    
     DETAILED DESCRIPTION 
       [0018]    The present invention relates to an improvement in passive temperature-controlled shipping. The following description is presented to enable one of ordinary skill in the art to make and use the invention as provided in the context of a particular application and its requirements. Various modifications to the preferred embodiment will be apparent to those with skill in the art, and the general principles defined herein may be applied to other embodiments. Therefore, the present invention is not intended to be limited to the particular embodiments shown and described, but is to be accorded the widest scope consistent with the principles and novel features herein disclosed. 
         [0019]    The inventors have developed a shipping system that monitors and controls the internal temperature of a container and its payload over long distance routes, with wide ambient temperature variations. The basic elements of the shipping system are: 
         [0020]    An insulated container with an internal payload space. In practice, this is a small to moderate sized container that can be lifted by hand. This container is called the Temperature-Controlled Container (TCC). The payload is typically a second secure container that fits inside the main container (TCC), referred to as the Payload Container (PC). 
         [0021]    Frozen gel packs (or dry ice or similar) are loaded inside the TCC to cool the payload inside and to absorb heat flux that enters through the TCC container&#39;s walls. 
         [0022]    The entire end-to-end route is broken into shorter hops between physical hubs. Service personnel at each hub are able to check the temperature status of each package. Temperature is measured using non-intrusive methods at each hub. TCC or PC containers are not opened for measurement. They remain undisturbed. 
         [0023]    If the measured internal temperature is above a trigger temperature, T trig , then the TCC container is opened and the gel packs (or other refrigerant) are replaced with fresh frozen gel packs or other refrigerant. The PC is never opened. This process occurs at each hub along the route. 
         [0024]    The end customer receives the TCC and PC combination. The internal payload temperature always stays between T low  and T hi , thus meeting the requirements for long distance transits with controlled and stable payload temperatures. 
         [0025]      FIG. 1  shows a basic flow and process steps for passive temperature-controlled transit. An example of the process is as follows: 
         [0026]    At the origin, load the sealed PC with its cargo, load the PC inside of the TCC, and load gel packs or equivalent into the TCC and seal the TCC. 
         [0027]    Ship to Hub_A (same country or different) with unpredictable ambient temperatures along the route. 
         [0028]    On receipt of the TCC at Hub_A, measure the internal temperature without opening the container. This can be done using non-intrusive methods such as described later. 
         [0029]    If the measured internal temperature, T meas , of the TCC is &gt;T trig  then open the TCC, replace the gel packs (or equivalent refrigerants) with fresh ones, and close and reseal the TCC. A measured value below T trig  provides confidence that the TCC can make the next leg of the transit with the payload temperature &lt;T hi  upon arrival at next stop. 
         [0030]    Ship to the next Hub or destination location. If sent to another hub such as Hub_B, repeat same process as at Hub_A. 
         [0031]    If the transit time between individual shipping points (origin, hubs, destination) is less than about 3 days then the internal TCC temperature can be maintained between T low  and t hi  along the entire route (up to 9 days with 2 hubs) from origin to destination given any required refrigerant recharges. These estimates are not fixed and longer transit times are possible with sufficient internal passive cooling and/or improved thermal insulation of the TCC. 
         [0032]    One embodiment of this invention focuses on maintaining the payload temperature between a T low  at 35° F. and a T hi  at 70° F. Other, bounds are possible. One purpose of this shipping system is to protect the payload against long exposure times to high ambient temperatures (such as T ambient &gt;80° F.) during a transit. 
         [0033]      FIG. 2  shows some components of one embodiment of the passive temperature-controlled shipping system. Cargo payload  201  may be any item(s), such as liquids, medical, pharmaceuticals, foods, or other items, that need shipping from a source to a destination under temperature-controlled conditions. In cases with a liquid cargo, the cargo may be pre-chilled to assist in the overall cooling of the shipping container&#39;s internal space. Cargo payload  201  is loaded into Payload Container (PC)  202  and secured such as by closing. This container may be locked or secured in any fashion and is typically never opened again except by the end-point receiving agent. 
         [0034]    Next, PC  202  is loaded into Temperature Controlled Container (TCC)  203 . Refrigerant  206  is also loaded into provided spaces inside TCC  203 . The refrigerant is secure and confined to 2 or more sides of TCC  203 . The exact number, placement, and location of the refrigerant may vary. However, the refrigerants should be placed such that a non-invasive temperature probe does not come into contact with refrigerants during measurement. So, typically, the refrigerants would be placed equally far apart from measurement location near door  204  so as not to bias the measurement. For example, if refrigerants are loaded along sides  1 ,  2  and  3  of TCC  203 , then the non-invasive measurement could occur on side  4 . 
         [0035]    One aspect of TCC  203 , not found on traditional insulated containers, is a small access port used to measure the internal temperature at the Hub. This port or door  204  may be cut into the corrugated top flap. Corrugated containers are not required but are one example embodiment. The top of the container is sealed with a flexible, inserted, insulated plug  205 . Other plugs or equivalent means are possible, and this is not an essential part of the shipping system. 
         [0036]    Once TCC  203  is loaded with PC  202  and refrigerants  206 , it is ready to be shipped to the first hub. The Hub is a geographic location able to support the following: 
         [0037]    1.) Shipping and receiving of TCCs  203   
         [0038]    2.) A Freezer unit to freeze the refrigerants, typically gel packs 
         [0039]    3.) Temperature probe  207  and temperature meter  208 , used to measure the internal temperature of all received TCCs. 
         [0040]    4.) Ability to open/reseal TCC  203  and replace its refrigerants with new frozen ones if the measured temperature is above a defined trigger point. 
         [0041]    Measurement Method 
         [0042]    It is important that the internal temperature is measured without disturbing the contents of the TCC. So, a non-intrusive technique to measure the internal temperature is desirable. Such a method includes the following steps: 
         [0043]    Open the small, hinged monitor door  204  in the top corrugated flap. 
         [0044]    Insert the long, thin probe  207  between insulated wall  210  and the side of the top plug,  205 . See insert  209 , shown with door  204  open. An 8-inch long probe, for example, is guided into the TCC to measure its quiescent temperature. The probe does not disturb the internal refrigerants or cargo. Meter  208  is allowed time to settle to a stable value before recording. 
         [0045]    Once the temperature is recorded, the probe is removed and port door  204  is securely closed. 
         [0046]    When using the probe method, the measured temperature, T meas , may be a predictable T offset  degrees higher than the actual payload cargo temperature, T payload . This may be because the inserted probe is not in direct contact with the cargo items inside the sealed PC. So T payload =T meas −T offset . Typically, T payload  load falls between the design limits T low  and T hi . The probe method may rely on this calibrated T offset  as part of the decision process of when to replace refrigerants. T offset  will typically be a small value ranging from near 0° F. to about 4° F. depending on PC material, cargo heat capacity, and other factors. 
         [0047]    Process Flow 
         [0048]      FIG. 3  shows a process flow of the temperature-controlled shipping system. The goal is to keep the Temperature Controlled Container (TCC) internal payload temperature within the bounds of T low  and T hi  during long transits with unpredictable high ambient temperatures. 
         [0049]    The process starts with step  301 , loading the Payload Container (PC) with the cargo payload. As an option, the payload may be pre-chilled before loading. For example, if the payload is bottled liquid it may be chilled to 50° F. before loading. The cooled liquid payload adds to the overall temperature stability inside the TCC during transit and reduces the need for additional loaded refrigerants. 
         [0050]    Step  302  adds the frozen gel packs or other refrigerant into the TCC. The total weight of the refrigerant (cooling power) is related to the transit time to the next stop, the expected ambient temperatures on route and the insulation strength of the TCC. Step  303  ships the TCC to the first Hub using conventional land, air or sea transport methods. 
         [0051]    At step  304 , the TCC is received at the Hub. Before shipment to the next hub or destination, the internal temperature, T meas , is measured. The measurement method is described earlier. 
         [0052]    At step  305 , if T meas  is greater than a predefined T trig , then proceed to step  307 . In step  307  the TCC is opened and the refrigerants removed and replaced with similar but frozen refrigerants. At step  308 , the TCC is resealed and sent to the next hub or destination. The refrigerant recharge provides sufficient cooling power for the next leg of the transit. The Payload Container is not opened. 
         [0053]    When the next hop is to another hub, step  310 , then the process is repeated from step  304 . When the next hop is the final destination, step  310 , then in step  309  the payload cargo (PC) is removed from the TCC at the final destination. 
         [0054]    At step  305 , if T meas  is less than or equal to a predefined T trig , then the process proceeds to step  306 . The refrigerants possess sufficient cooling power for the next leg of the transit. In step  306  the TCC is not opened and is sent to the next hub or destination. 
         [0055]    When the next hop is to another hub, step  311 , then the process is repeated from step  304 . When the next hop is the final destination, step  311 , then in step  309  the payload cargo (PC) is removed from the TCC at the final destination. 
         [0056]    The hub processing loops (steps  305 - 307 - 308 - 310 - 304 ) or (steps  305 - 306 - 311 - 304 ) are executed as required until the entire procedure ends at step  309 , the end of the shipping process. 
       ALTERNATE EMBODIMENTS 
       [0057]    Several other embodiments are contemplated by the inventors. For example, there may be one hub or more than one hub. The payload container and temperature-controlled container may have various shapes and sizes and are not limited to boxes. They may be made from corrugated cardboard, wood, or from other materials. The PC and TCC could be made from different materials. For example, the PC could be a wood box containing wine bottles, while the TCC is a cardboard box. 
         [0058]    While a single payload container has been described, each TCC could have more than one payload container. The number of gel packs could be increased, and various arrangements of gel packs may be used. 
         [0059]    This temperature-controlled shipping system does not require the use of the probe method to determine T payload . There are other methods to non-intrusively measure the internal TCC temperature. One method is to place the active end of a thermocouple wire inside the TCC and thread the other end to the access port door  204 . This method does not require a probe but relies on the thermocouple wire end point to measure the internal temperature. Another method relies on an inserted temperature monitor module that communicates wirelessly to an external recording device or meter. There are many methods to non-invasively measure the internal temperature of the TCC. The payload container may be temporarily removed from the TCC at the hub to allow a refrigerant pack placed underneath the payload container to be replaced at the hub. 
         [0060]    An internal temperature sensor could have a radio or other transmitter to allow the temperature to be read wirelessly, such as by WiFi, Bluetooth, or Radio-Frequency Identification (RFID) where the ID is adjusted by the temperature sensor. An internal power source such as a small battery may be included for the radio transmitter, or power may be coupled into the internal temperature sensor inductively. 
         [0061]    Mixed modes of transport may be used. For example, trucking may be used for one leg, while a cargo ship is used for another leg. Air may be used for other legs. One hop between hubs may include several modes of transport, such as a ship and local trucks. Standard tracking methods such as reading bar codes may be used at hubs to identify boxes for temperature-controlled processing, or the TCC could be addressed and delivered to a facility at each hub. A new shipping label could be affixed at each hub. 
         [0062]    While upper and lower limit temperatures have been described, only an upper temperature limit may be used. Alternately, only a lower temperature limit may be used, such as to prevent damage due to extremely low temperatures in the unpressurized cargo holds of airplanes. The shipping system could be combined with other shipping systems and methods. 
         [0063]    The trigger temperature could be the same at all hubs, or could be set to different temperatures at different hubs. Hubs before longer or slower transit links could have lower trigger temperatures to compensate for additional distances and expected heating. Trigger temperatures could also differ for different types or sizes/masses of payloads. 
         [0064]    The background of the invention section may contain background information about the problem or environment of the invention rather than describe prior art by others. Thus inclusion of material in the background section is not an admission of prior art by the Applicant. 
         [0065]    Any advantages and benefits described may not apply to all embodiments of the invention. When the word “means” is recited in a claim element, Applicant intends for the claim element to fall under 35 USC Sect. 112, paragraph 6. Often a label of one or more words precedes the word “means”. The word or words preceding the word “means” is a label intended to ease referencing of claim elements and is not intended to convey a structural limitation. Such means-plus-function claims are intended to cover not only the structures described herein for performing the function and their structural equivalents, but also equivalent structures. For example, although a nail and a screw have different structures, they are equivalent structures since they both perform the function of fastening. Claims that do not use the word “means” are not intended to fall under 35 USC Sect. 112, paragraph 6. 
         [0066]    The foregoing description of the embodiments of the invention has been presented for the purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed. Many modifications and variations are possible in light of the above teaching. It is intended that the scope of the invention be limited not by this detailed description, but rather by the claims appended hereto.