US 3807194 A
A thermodynamic container comprising a double walled, insulated, plastic outer shell having a thermal energy storage material sealed thereto. The thermal energy storage material coacts with a heat exchanging plastic cup adapted to receive a product to be stored. The thermal energy storage material is a pure compound formulated for the specific temperature desired for the stored product, solid or liquid. The container is capable of storing a product for a preselected period with the product having the desired temperature at the conclusion of the period.
Claims available in
Description (OCR text may contain errors)
United States Patent  Bond [451 Apr. 30, 1974 THERMODYNAMIC CONTAINER  Inventor: Thomas G. Bond, Placentia, Calif.-  Assignee: Royal Industries, Inc., Pasadena,
22 Filed: Oct. 12,1972 21 Appl. No.: 296,785
 US. Cl 62/457, 62/430, 62/438,
62/371  Int. Cl. F2511 3/08  Field of Search 62/430, 438, 457, 371
 References Cited UNITED STATES PATENTS 624,168 5/1899 907,099 12/1908 1,369,367 2/1921 1,199,593 9/1916 1,641,192 9/1927 Olin 62/457 3,302,427 2/1967 Stoner 62/457 3,406,532 10/1968 Round 62/457 3,603,106 9/1971 Ryan 62/457 Primary Examiner-William J. Wye Attorney, Agent, or Firm-Christie, Parker & Hale ABSTRACT 14 Claims, 2 Drawing Figures PATENTED APR 3 01974 sum 2 or 2 F/EE THERMODYNAMIC CONTAINER This invention relates to a thermodynamic container and more particularly to containers employing heat storage materials for maintaining products stored in the containers at a preselected temperature in accordance with the desired temperature for the use or consumption of the selected stored product.
PRIOR ART At the present time, there are various types of containers that are known in the prior art, some of which are commercially available. These prior art containers include insulated containers made of plastic or the like, vacuum or thermos bottles and cups and containers employing heat storage materials or eutectic compounds. The insulated containers that are commercially available are in the form of small insulated cups which consist basically of a plastic shell which may be constructed of a polypropylene material. Some of these cups include a low density foam plastic insulation in addition tothe basic plastic shell. It is also known that some of the cups that are commercially available and constructed as mentioned hereinabove, may include a thin wafer of water in the lid of the cup which may be frozen to provide some cold storage capabilities around 32 F. These cups usually have their lids insulated with cork rather than a foam plastic. In general, the construction of this type of prior art cup is in terms of snap fitting the parts together or spin welded pieces. Due to the lack of the incorporation of a thermal energy storage material in these cups, the insulating properties and thereby the use thereof is. limited to a relatively short product storage period.
A well-known type of thermodynamic container that has been used extensively is the vacuum bottle carrier which is also known as a thermos bottle. A true vacuum bottle carrier has superior heat retention characteristics relative to any presently known thermodynamic container. A true vacuum bottle, however, is a relatively expensive container. Inexpensive vacuum bottles have been produced and are commercially available that sell for approximately $2.50. The less expensive vacuum bottles that are commercially available have been found to be disadvantageous since they are highly subject to damage from being dropped or thrown. The damage prone characteristics of these inexpensive vacuum or thermos bottles results from the fragile nature of the glass bottle that is employed in combination with an inadequate suspension system. The suspension and cushioning system of such a vacuum bottle is not adequate to sustain the mechanical shocks and they have been found to have a relatively short life expectancy,
particularly when used by school children. As to the true vacuum bottle (a more expensive type) from the standpoint of maintaining hot foods at desired temperatures, the heat retention characteristics of su'ch a vacuum bottle are so good that it may produce stored foods that are too hot to be consumed and must be cooled before eaten. Stated differently, the desired eating temperature for such hot foods is not realized through the use of a true vacuum bottle whereby the user may be burned from eating hot soup or similar hot foods.
Other thermodynamic containers employ eutectic materials for their particular function. One such thermodynamic container is described in U. S. Pat. No. 3,603,106. In this prior art type of container, 3. separate heat exchanger element adhesively bonded to the shell is employed. The purpose of such eutectic cups is generally to cool products to a specific temperature. The products used with such eutectic containers are coffee, tea and the like. Accordingly, there is a present need in the market place for an inexpensive and effective thermodynamic container that has energy storage properties which allows a product to be stored for a preselected period so that it will be at the correct temperature when it is desired to use the product or the product is to be consumed. Preferably, the thermodynamic container should be less expensive than the true vacuum bottle, be reuseable a multiplicity of times and should be constructed so as to have a relatively long life, including when used by children.
DISCLOSURE OF THE INVENTION of a thermal energy storage material in an improved combination of elements comprising the container. The cost of the container of the present invention is less than the inexpensive vacuum bottle referred to hereinabove. In a container of the present invention, the product stored within the container can be maintained at a specific temperature best suited'to the product requirements. To this end, for example, soup can be kept at 130 F for 5 hours at a normal schoolroom ambient temperature and be ready to eat at noontime. In the same fashion, gelatins and puddings can be kept at 40 F for a similar period. Ice cream can be kept frozen for 4,to 5 hours by using a 0 F energy storage material in the container of the present invention. This type of temperature storage capability is greatly superior to existing insulating containers as the result of a combination of eutectic heat exchangers and the improved insulation system employed in the thermodynamic container of the present invention. For example, comparison tests performed with the existing commercially available insulated cups show that the identical product load of hot food is 35 F cooler at the end of the 5 hours in an insulated cup without an energy storage material thanthe same product load in the thermodynamic container of the present invention. During this test, the product temperature at the end of the 5 hours was in the insulated cup and in the container of the present invention. It should also be noted that some products cannot be carried in the existing insulated cups. For example, ice cream will melt and gelatin will lose its form when stored in such prior art containers. Similarly, prepared food which should be hot when eaten falls substantially below body temperature and chilled products, such as soups, become warm in the existing insulated containers.
From a structural standpoint, the present invention provides a temperature controlling container comprising a double walled outer shell having an internal product storage cavity to receive and store the product which is to be temperature controlled. The temperature control is in terms of both maintaining the product at a low temperature or a high temperature relative to the ambient temperature in which the container is employed. A thermal insulator is arranged-between the double walls of the shell. In combination with the outer shell, a heat exchange cup having a layer of thermal energy storage material covering the sides and bottom of the cup is employed. The cup is mounted in the cavity of the outer shell with the storage material in intimate contact with the inner walls of the shell. The cup is secured to the inner wall of the shell to thereby seal the energy storage material between the cup and the inner wall. An insulative closure can be adapted to be secured to the outer shell and to thermally enclose the outer shell and thereby the heat exchanging cup.
These and other features of the present invention may be more fully appreciated when considered in the light of the following specification and drawings, in which:
FIG. 1 is an exploded view of the thermodynamic container of the present invention illustrating a sealed food container to be stored in the temperature controlling container embodying the present invention; and
FIG. 2 is a cross sectional view of the thermodynamic container of FIG. 1 illustrating the closure secured thereto. I
Now referring to the drawings, the construction of the thermodynamic container of the present invention will be described in detail. It should be noted at the outset that the container is particularly constructed and defined to' accept a commercially available food container in the form of a sealed tin can and the invention will be described for such a use. However, it should'be understood that the container 10 can be used for the storage of liquids or foods that come into direct contact with the container without any direct chemical or toxicological effects on the stored product. The container 10 comprises a temperature controlling carrier 11 having an internal product storage cavity 12 for accepting a sealed container 13 that has been temperature conditioned to the desired temperature either above or below the ambient temperature such as the tin can 13 illustrated in FIG. 1. The temperature controlling carrier 11 may include a closure 14 adapted to be secured to the carrrier 11 for sealing the food container 13 within the product storage cavity 12.
Specifically referring to FIG. 2, the details of the internal construction of the container 10 will become apparent. The temperature controlling carrier 11 comprises an open ended, double walled outer shell that may be constructed of plastic material preferably of a molded polypropylene. The entire double walled shell is produced as a unitary structure to receive a thermal insulating material between the.volume defined by the double walls 11' and 11'. This volume of material is filled with a rigid thermal insulator 15, preferably a rigid urethane material to completely fill up the spacebetween the walls ll" and 11. The thermal insulating material that has been found to have the necessary advantageous insulating properties is a rigid polyurethane system that has an insulation K factor of at least 0.15
and consists of diphenylmethane diisocyanate (MDl). It has been found that due to the other parameters and materials used for the container 10, no other material commercially available provides a comparable insulative K factor or insulating value for the purposes of the present invention. The chemical properties of such rigid polyurethane systems are described in standard commercial literature. Such polyurethane systems will be purchased from either Urethane Systems, Inc. of 416 W. El Segundo Blvd., Gardena, Calif, or from Polymir Industries of 520 W. Walnut, Orange, Calif, 92668 as MDI-CFD-l25 2 lbs. per cubic foot. The openended bottom section of the double walled outer shell 11 may be enclosed after the thermal insulator 15 is placed between the walls of the shell 11 by means of a base retaining disc 16, that may be sonic welded to the outer shell 11, thus forming a completely sealed unit. For this purpose the base disc 16 may comprise a thin molded polypropylene disc.
The double walled outer shell, or carrier 11, is of a substantially U-shaped configuration and thereby defines an internal product storage cavity 12 between the inner walls 11. Within the .inner cavity there is positioned a heat exchanging cup 17 that is constructed of a plastic material and preferably the same plastic material that the outer shell 11 is. constructed of. Specifically, the heat exchanging cup 17 is constructed of a molded polypropylene. The heat exchanging cup 17 is welded or heat sealed at its upper edges to the inner wall 11 of the double walled shell 11, as indicated in FIG. 2'by the reference number 18. The inner wall of 'the heat exchanging cup 17 may be defined as a fluted or corrugated structure toincrease theheat transfer area afforded by the cup 17 and also provide added structural strength for the container. The entire inner wall of thecup 17 may be fluted as indicated by the reference number 17.
It should be noted at this point that because the cup 17 and the shell 11 are constructed of the same plastic material and are welded or heat sealed together without resorting to adhesives or artificial connectors, the
container 10 can be reused extensively and by washing after use, including being subjected to the extreme temperatures prevailing in a home dishwasher. With the two basic elements of the container 10 constructed of the same material, the coefficients of thermal expansion and contraction of these elements is identical so that the container 10 can be subjected to temperature extremes without the fear of harm to the container due to separation of the various parts such as could occur to a' thermodynamic container comprising different materials having greatly different thermal characteristics. For example, the use of a plastic material in combination with aluminum material exhibits coefficients of thermal expansion which are significantly different so that the use of these materials over a long period of time could create wear and leakage problems at the joints of the two materials.
The remaining element of the temperature controlling carrierl 1 is the thermal energy storage material 19 arranged in the sealed cavity defined between the outer wall and bottom of the cup'17 and the adjacent 'walls of the inner wall 11 of the double walled shell 11. The thermal energy storage material 10, when arranged in this fashion, is sealed around the sides and bottom of the heat exchanging cup 17 by the heat 'seal' 18, thereby eliminating any leakage into the product storage cavity l2 and the product stored therein. The thermal energy storage material 19 is selected to maintain the product stored within the cup 17 at a preselected temperature. For this purpose, the thermal energy storage material 19 is a eutectic compound that is specifically formulated for the desired temperature at which the product carried by the cup 17 is to be stored. A wide range of specific temperatures can be maintained by the container 10 through the selection of the particular eutectic materials. For example, temperatures such as 150, 140, 130, 65, 40, 27, 12 and 0 may be provided. These eutectic materials are well known in the art and have different heats of fusion depending upon their formulations to provide a desired temperature. A 150 F temperature may be maintained for a stored product by using a thermal energy storage material described in the Telkes/U.S. Pat. No. 2,936,741. If a 97 F environment is to be provided for the material, the material described in the Telkes/U.S. Pat. No. 2,677,367 may be employed. For transportation and storage of ice cream and frozen ices wherein a 12 F environment must be provided, a material composed of potassium chloride and water may beemployed. Other temperatures maybe provided'through the formulation of various other materials such as various other eutectic compounds in accordance with the desired temperature. Other materials for the purposes of the present invention are described in the Telkes/U.S. Pat. Nos. 2,677,664 and 2,989,856. The compounds for the thermal energy storage materials described in each of the aforementioned Telkes U. S. patents are incorporated herein by reference.
lt is preferable to employ a thermal energy storage material that is non-toxic or non-corrosive, particularly when foods are being stored, since leakage of the material into a food product would drastically alter the taste of the food and spoil it for human consumption. The
sealing of the thermal energy storage'material within the carrier 11 renders the container less prone to leakage and escape into the product storage cavity 12.
It should be noted that the use of an integral plastic heat exchanging cup 17 permits the container 10 to use the full range of eutectic materials from hot to very cold materials. Many known eutectic materials, particularly those providing cold temperatures, are corrosive to heat exchanging elements 'such as aluminum. so that the all-plastic construction afforded by the present invention obviates these inherent problems. Due to the nature of the heat exchanging structure, the plastics used and the deposition techniques for the eutectic materials employed comprising pure compounds that do not require heat transfer augmentation such as aluminum powder or copper mesh, all of the space available between the inner walls 11 and the heat exchanging cup 17 is available to carry and store the thermal energy storage material 19 and none of the space is devoted to heat transfer augmentation materials. These parameters permit a complete phase change of the thermal energy storage to occur in the proper functioning of the container 10. Therefore, the full phase change energy storage capabilities of the material 19 is employed. Failure of the material 19 to experience a complete transition will result in significantly reducedcapability crystallization. This is accomplished by placing the heat exchanging cup 17 into a molten solution of the selected eutectic compound. The molten solution of the eutectic compound-should be maintained at a temperature of 20 F above the operating temperature of the eutectic compound. Under these conditions, the cup 17 is suspended into this heated solution and cooling is allowed to occur to induce crystallization of the eutectic material to the sides and bottom of the cup. The rate of crystallization varies with each material and is determinable. It should be noted that when the heat exchanging cup 17 is prepared in this fashion, the thermal energy storage material is deposited thereon in an amount and thickness that is carefully regulated to insure that a uniform layer of material is deposited to insure the even and rapid transfer of heat during the conditioning phase of the thermal energy storage material and a uniform transfer of heat to the stored product when the container 10 is in use. The heat exchanging cup 17, carrying the deposited thermal energy storage material 19, may then be placed into the internal cavity providedby the double walled shell 11 and then welded to the shell such as by heat sealing or the like. When the thermal energy storage material 19 is completely sealed in this fashion, no opportunity is afforded for escape of the thermal energy storage material for contamination of the productstored within the cup 17. 'Also, it will be noted that the heat exchanging cup 17 becomes an integral part of the cup shell 11 without resorting to ad hesives or artificial connectors.
A very important aspect of the present invention appears to be the critical parameters that are necessary for the proper operation of the container 10. The walls of the cup 17 must be extremely thin to permit rapid conditioning of the thermal energy source material 19.
To this end, in one practical embodiment of the invention the walls of the cup 17 are defined on the order of 0.035 inch. It also appears that the deposition of the energy storage material 19 onto the wall of the heat exchanging cup 17 must be induced by crystallization and also be extremely thin, on the order of one-eighth of an inch. In conjunction with these critical conditions, it has been found that because of the very thin wall of the cup 17 and the relatively small amount of energy that may be stored in the thermal energy storage material 19, that only the rigid polyurethane system affords the necessary insulating properties for proper operation. As a result of the special attention to the aforementioned parameters, the thin layer of energy storage material 19 is readily melted or solidified by the conditioning process and allows complete phase change of the thermal energy material 19 to take place during the proper operation of the container 10. This allows the full energy capabilities of the storage materials to be employed. In conformance with the aforementioned parameters, to assure maximum performance of the container 10 of the present invention, the internal cavity for the heat exchanging cup 17 should provide a close physical contact between the container 13 and the adjacent wall of the cup. A close physical fit or contact with the walls of'the cup avoids heat losses that would occur if a space isallowed between the container 13 and the cup 17.
The container 11, constructed in this fashion, may
also include a ring element 20 mounted to the inner wall 11 above the outer periphery of the cup 17 to further secure the cup in position and enclose the joint 18 between the cup 17 and the wall 11. The retaining ring 20 may also be constructed of a plastic material and preferably a molded polyethylene.
The closure or lid 14 for the container 10 may be constructed and defined to secure and seal the interior of the double walled shell 11 carrying the cup 17. For
this purpose, the closure 14 may be of a screw type to be-threaded onto the outer wall 11 of the carrier 11 adjacent its top as best illustrated in FIG. 2. To this end, the inner wall 14 of the closure is defined to be threaded onto the carrier 11 as illustrated. The closure 14 as constructed and defined is made of the same plastic material as the shell 11 and the cup 17, namely, a molded polypropylene. The closure 14 is constructed with a dependent portion having a thermal insulator stored therein. The thermal insulator is identified by the reference numeral 21 and comprises a rigid urethane material such as employed for the double walled shell 11. As is evident from examining FIG. 2, the thermal insulator 21 is enclosed by means of an insert that is press fit into the closure 14. The insert is also constructed of a plastic material preferably of a molded polypropylene, the same as the closure proper.
With the above construction in mind, the principles of operation of the container may now be examined. The container 10 .operates by taking advantage of the heat of fusion or heat of crystallization of the thermal energy storage material '19 to provide an energy source to maintain the product, food or liquid, stored in the cup 17 at a preselected temperature. The energy available from fusion or crystallization is conserved or directed by the insulator 15 in which the cup 17 is contained. By this method, a preselected temperature is established within the product stored in the cup 17 and may be maintained for a specified period of time depending upon the ambient temperature in which the container 10 is employed. It will be assumed that the r z w sm aatyre in the Emily- The energy necessary to cause the phase change ph e nomenon to occur is supplied from at least two sources. The can 13, or other container of food, which is placed in the cup 17 must be above the final desired temperature, if the cup is to keep the food warm, Similarly, the product placed in the cup 17 must be below the desired temperature if the cup is to be used to keep the product chilled. Therefore, the primary energy source to activate the thermal energy storage material 19 is provided by the product stored within the cup 17. The second source of energy for activating the thermal energy storage material 19 is supplied from an external source. This source of'energy'can be supplied by placing the container 10 in the refrigerator for a preseribed period of time prior to its intended use, if it desired to keep the product within the container chilled. This would freeze or crystalize the thermal energy storage material 19 and provide the necessary cold energy required to keep the food in a chilled condition. Alternatively, in the event the container is used to keep a product warm, hot water at least 20 F over the desired operating temperature should be circulated through the inside of-the cup for at least five minutes to charge the thermal energy storage material 19.
With the above considerations in mind, the thermo dynamic container 10 will be described as it can be conditioned for the purposes of storing a sealed can 13 having a food product stored therein. For this purpose,
it is desired to maintain the container 10 in an ambient temperature of 75 F and to keep a sealed can 13 of a food product at a temperature of at least 125 F for 5 hours. To use the container 10 for such an application, it is necessary to bring the contents of the can 13 to 175 F by immersing the sealed can into boiling water for 15 minutes. While the can 13 is heating, the container 10 is conditioned by pouring boiling water into the container 10, loosely replacing the closure 14 and allowing the hot water to stand in the container for 5 minutes. After the can 13 has been heated to the desired temperature, the container 10 is emptied of the hot water. The heated can 13 is inserted into the cup 17 and the closure 14 is secured to the carrier 11. The can 13 remains sealed at all times until it is opened for consumption. Under th ese conditions it has been found that the food stored within the tin can 13 is at the correct and desired temperature for consumption at the end of 5 hours..lt has been found that a sealed can 13 of chili beans and franks has been maintained at a temperature of l29.2 F, a sealed can of spaghetti has been maintained at a temperature of 130.0 F. and a sealed can of beef stew has been maintained at a temperature of 129.2 F. Alternatively, the container 10.may be used to maintain a product in a chilled condition by following the aforementioned steps. In this respect, the
product is chilled below the desired temperature and the container cooled by placing it in a refrigerator to solidify the material 19 prior to insertion and storing the chilled product.
What is claimed is:
1. A temperature controlling container comprising a double walled outer shell constructed of a plastic material having an internal cavity, and
a thermal insulator arranged between the double walls of the shell, a heat exchanging cup constructed of the same plastic material as the shell having a layer of a thermal energy storage material covering the sides and bottom of the cup, said thermal energy storage material is a eutectic compound formulated for a temperature selected relative to' storage material between the cup and said inner wall. 7 2. A temperature controlling container as defined in claim 1 including an insulative cover adapted to be secured'to the outer shell and to thermally enclose the outer shell and thereby the cup.
v3. A temperature controlling container comprising a double walled, insulative plastic outer shell havin an internal cavity,
a rigid thermal insulator filling the volume between the double walls of the shell and being completely enclosed within the outer shell,
a thin walled plastic heat exchanging cup mounted in the cavity of the outer shell and being welded to the shell so as to be integral therewith and defining a cavity between the inner wall of the shell and the outer wall and bottom of the cup, and
-a thermal energy storage material sealed inthe cavity defined between the cup and the inner wall of the shell in intimatethermal contact with the' walls defining the cavity to allow the cup to function as a heatexchanger between the energy storage material and a product stored in thecup to be maintained at a preselected temperature, the heat flow through the cup being bidirectional.
4. A temperature controlling container as defined in claim 3 wherein the rigid insulator comprises a polyurethane system.
5. A temperature controlling container as defined in claim 4 wherein the insulator has a K factor of at least 0.15 and consists of diphenylmethane diisocyanate.
6. A temperature controlling container as defined in claim 3 wherein the shell comprises a molded polypropylene.
7. A temperature controlling container as defined in claim 6 wherein the cup comprises a molded polypropylene.
8. An all-plastic temperature controlling storage container comprising a thin walled substantially U-shaped plastic container adapted to receive a product, a solid or liquid, to be maintained at a preselected temperature;
solid insulating plastic means having a substantially U-shaped configuration for receiving the container therein and being sealed thereto without any adhesives or artificial bonding agents, the plastic for the container and the insulating means being constructed of the same plastic material to allow it to be sealed,
the insulating means and the container being constructed and defined for providing a sealed cavity between the container and the insulating means,
and a thermal energy storage material stored in the thus defined sealed cavity and in intimate contact with the walls defining the sealed cavity, the energy storage material comprising a eutectic material for maintaining a product stored in the thin walled container at a preselected temperature, the energy storage material being adapted to store thermal energy in response to the difference in temperature of a product stored in the container and the material as a result of the exchange of heat through the thin walled container whereby. the thermal energy stored by the material is released tothe product when the product exceeds the preselected temperature, the thermal energy material exhibiting a complete fusion of crystallization cycle for the exercise of its full energy storage capabilities.
9. An all-plastic temperature controlling storage container as defined in claim 8 including a solid insulative cover for securing and sealing said solid insulating means and any product stored therein.
10. An all-plastic temperature controlling storage container as defined in claim 8 wherein the thin walled container has its inner wall fluted for increasing the heat transfer area of the container and providing additional structural strength.
11. An all-plastic temperature controlling storage container as defined in claim 8 wherein thermal energy storage material is a pure euctectic compound deposited on and carried by said U-shaped container.
12. A temperature controlling container comprising a substantially U-shaped, solid, relatively thick insulative housing,
a heat exchanging cup having a thin layer of thermal energy storage eutectic compound deposited on the outer sides and bottom of the cup by inducing crystallization of the eutectic onto the sides and bottom of the cup, the cup being heat sealed to said solid insulating housing to thereby seal the thermal energy layer therebetween whereby leakage of the heat storage material during normal operation is prevented.
13. A temperature controlling container as defined in claim 12 wherein the eutectic compound is deposited onthe cup by suspending the cup in a molten solution of the compound to induce crystallization of the eutectic onto the cup.
14. A temperature controlling container as defined in claim 12 wherein the cup has serrated walls and the housing is provided with a screw-type lid for providing a liquid-tight seal for the housing.