Heater device

Abstract

A heater device that includes an outer container formed from a vapor impervious material and holds a quantity of heat generating material. A second container is positioned inside the outer container and hold an activation material. A seal on the second container is adapted to be opened to transfer the activation material into contact with the heat generating material to generate heat. The device is useful in heating food such as military field rations.

Description

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application is a continuation-in-part of Pan In Pan Heater application filed Oct. 4, 2007, having Ser. No. 11/973,178.

BACKGROUND

This invention relates to a device for heating the contents of a container and for keeping it warm. More particularly, the invention relates to a self-contained heater device that allows the contents such as food in a container to be heated.

Often times, it is desirable to heat food and other items at a location remote from a source of heat such as a stove or oven. Other times it is desirable to take warmed or hot food and other items from the place of heating to another location, such as a picnic, school or church basement, scout meeting and any of the myriad of events that do not meet or gather where heat is available. Sometimes the location is in a location where fire is not permitted, such as a class room or outdoors during the dry season. It is also important for military personnel to have access to warm food, particularly when deployed in locations remote from their base or station.

One such self-contained warmer is disclosed in U.S. Patent Application Publication No. US 2007/0034202, to Punphrey et al. in which a container with an exothermic composition is used to heat a vessel. A membrane is used to cover the exothermic composition, which is then activated by removal of the membrane. Various compositions are disclosed that are based on iron oxidation chemistry. The heater is in direct contact with the container and must be put on a heat-resistant surface to be used without damage.

U.S. Pat. No. 6,705,309 discloses a self-heating or self-cooling container in which tubular walls defining an internal cavity into which steam or hot air is placed as a source of heat. This, of course, requires a source of that heated material.

Other heater devices for food generate heat by chemical reaction, and in so doing generate hot gases, steam or hot water vapor, which is potentially hazardous to the user and which may, in some instances, contribute to pollution of the environment.

It would be a great advantage if a way of heating containers could be developed that have a controlled release of heat that is within acceptable safety limits.

Another advantage would be to provide a way of heating containers that produces heat over an extended period of time, rather than simply having an exothermic reaction that lasts a few minutes or less.

Yet another advantage would be to provide a way to generate heat by an exothermic reaction without releasing any gas, steam or hot water vapor to outside the device.

Other advantages will appear hereinafter.

SUMMARY

The unique aspect of this invention is that a controlled, dispersed exothermic reaction can be used to heat or cook the contents of a container quickly and effectively while maintaining the heat for an extended period of time without releasing any of the reaction products to outside of the device.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view of one embodiment of this invention.

FIG. 2 is a schematic view of another embodiment of this invention.

FIG. 3 is a schematic view of another embodiment of this invention.

FIG. 4 is a schematic view of another embodiment of this invention.

FIG. 5 is a schematic view of another embodiment of this invention.

FIGS. 6a and 6b are illustrations of one actuator for this invention.

FIGS. 7a and 7b are illustrations of another actuator for this invention.

FIGS. 8a and 8b are illustrations of another actuator for this invention.

DETAILED DESCRIPTION

The heater device of this invention is shown generally in FIGS. 1 and 2. The device, 10 generally, includes an outer container 11 formed from a vapor impervious material. Preferred is an outer container 11 made from Aclar®, which is a polychlorotrifluoroethylene (PCTFE) material manufactured and sold by Honeywell International Inc. Aclar film is crystal clear, biochemically inert, chemical-resistant, nonflammable, and plasticizer- and stabilizer-free. Aclar laminates provide a wide range of gauges and thus barrier levels to allow flexibility in selecting the optimum barrier level for the chemical system chosen. Other similar pouch materials may be used as well. All that is required is that the material have a functional moisture and vapor barrier for the other components of the invention

A second container 13 is inside container 11, in FIG. 1 by a seal wall 15 that divides container 11 into two chambers. Second container 13 may be made from a similar material as noted above, or may be of slightly less strength because it is to be opened, as described herein. A flexible actuator 17 is attached to seal 15, and extends through the wall of container 11. Pulling on actuator 17, which may be a string attached to a seal strip, releases the activation material 18 into the outer container 11 for reaction with heat generating material 19.

Another embodiment for second container 13 is to have a quantity of air inside container 13 and have seal 15 be sufficiently fragile that pressure on the air in container 13 would cause seal 15 to burst.

In FIG. 2, outer container 21 has a complete second container 23 inside, and the activation agent 28 is released for contact with heat generating material 29 by placing pressure on actuator 27 which pierces seal 25.

FIG. 3 illustrates the use of this invention with a box 30 that contains food or other material that is to be heated. Typical food boxes are what is known in the military as MRE, which is an acronym for “meals ready to eat.” Here outer container 31 has a second container 33 which has two seal walls 35a and 35b. The actuator is in the form of a valve 37a and 37b than can be pulled to open through the outer wall of outer container 31 because container 31 is sufficiently flexible to allow a user to contact and release valves 37a and 37b. Activation agent 38 contacts heat generating materials 39a and 39b on both sides of container 31. A strap or band 34 is also optionally provided to hold box 30 between the two parts of container 31.

FIG. 4 illustrates another embodiment for a MRE or other box 40. A package 42 is sized to accept MRE 40 and a pair of heater devices 41a and 41b, as described above, are also inside the box and positioned on two sides of MRE 40.

FIG. 5 illustrates another embodiment in which a tray 50 that contains food or other items to be heated has the outer container 51 on one side of tray 50. Inner container 53 includes a seal 57 in the form of a score line so that when container 51 is flexed, seal 57 is ruptured or broken and activation agent 58 contacts heat generating material 59 to heat the contents of tray 50.

The activation element in FIGS. 6a and 6b are to be placed inside the inner container 13 of FIG. 1 or others container within the scope of this invention. The inner container is made from a flexible, pierceable material such as polyethylene or any of the conventional plastics. The activation element of FIGS. 6a and 6b is in the form of a strip 69 of relatively rigid plastic, although other materials can be used. Strip 69 has a triangle 68 cut into its surface and when the strip 69 is bent, triangle 68 protrudes and penetrates the wall of the container 13. The sharp end of triangle 68 pierces the side of the inner container or pouch 13, and heat is generated.

The activation element in FIGS. 7a and 7b is a semi-flexible strip 79 that is longer that inner container 75, as shown in FIG. 2 as activator 27 inside container 23. Strip 79 is bent into a bowed shape so that it fits inside container 75 and has at least one sharp end 76 that punctures inner container 75 when the container 75 and strip 79 are flexed, thereby straightening strip 79 and puncturing the end of container 75.

The activation element in FIGS. 8a and 8b is formed in inner container 85 that has a rigid side, 83, shown here, that has a score 89 cut in the rigid side. The other side, 87 is flexible. This is the actuator shown in FIG. 5. When container 85 is flexed or bent, score 89 ruptures and the contents in container 85 are driven into the outer container, such as outer container 51 of FIG. 5.

There are a number of combinations of heat generating materials and activating agents that are suitable for use in the present invention. The selection of specific components is to be based upon cost, compatibility, ease of control of the exotherm, and other factors.

The preferred activating material of this invention is water. This is plentiful and safe, and reacts with a number of materials to produce an exothermic reaction.

The preferred heat generating material is a solid formed from several components that, when free from moisture, are stable for up to three to five years or more, and which react when moisture is present to generate heat. The preferred solid is made from crystalline calcium oxide, a zeolite powder, and a polyalkyl glycol such as polyethylene glycol. The amount of activation material, such as water, is preferably from about 75 to 125 weight percent, based upon the total weight of heat generating material. Approximately equal amounts by weight of water and heat generating material is the preferred ratio.

The amount of calcium oxide ranges from about 30 to 70 weight percent, the amount of polyethylene glycol ranges from about 15 to about 35 weight percent, and the amount of zeolite ranges from about 15 to about 35 weight percent, based on the total weight of heat generating material. Preferred is about 25 weight percent each of the polyethylene glycol and zeolite and about 50 weight percent calcium oxide.

The heat generation material most preferred, using the above components includes a calcined calcium oxide. This material is available as a small particle size, with a diameter less than about 0.2 mm, and as a particle of somewhere between 0.2 and 0.8 mm. Larger particles are ground and smaller ones sieved, and the calcium oxide is then calcined. It has been found to be effective to calcine for at least 60 to 120 minutes, and preferably about 90 minutes, at temperatures above 500° C., and most preferably at about 550° C. for that period of time. The calcined calcium oxide is, of course, desiccated to prevent any contamination by moisture.

More than 150 zeolite types have been synthesized and 48 naturally occurring zeolites are known. They are basically hydrated alumino-silicate minerals with an “open” structure that can accommodate a wide variety of positive ions, such as Na+, K+, Ca₂+, Mg₂+ and others. These positive ions are rather loosely held and can readily be exchanged for others in a contact solution. Some of the more common mineral zeolites are: analcime, chabazite, heulandite, natrolite, phillipsite, and stilbite. An example mineral formula is: Na₂Al₂Si₃O₁₀-16H₂O. Zeolites, by their nature, are finely porous structures that are “hungry” for water and that have the ability to hold heat. In the present invention, the activation agent, water in the preferred embodiment, enters into the zeolite pores, trapping the water as it is heated by reacting with the calcium oxide, thus storing heat, providing a longer, more evenly distributed supply of useable heat.

The polyethylene glycol component of the heat generating material is admixed with the calcium oxide and zeolite and placed in the outer container as described above. When the activation agent, water, is introduced into the heat generating material, the polyethylene glycol coats the calcium oxide and zeolite, further delaying the exothermic reaction between calcium oxide and water, and adding to the utility of this invention.

The present invention provides a significant advantage over the prior art in several ways. Because the outer container is sealed, as described above, the exothermic reaction when heat is generated does not release steam or other vapor as do presently available heaters. In addition, the heater device of this invention is much more effective that what has been done in the past. The heater of this invention has been used to heat products to 150° F. within 5 minutes and maintained the heat at or above 140° F. for 50 minutes. Prior art devices take 12 minutes to reach only 140° F. and only hold that temperature for 20 minutes.

Although the present invention has been described with reference to preferred embodiments, workers skilled in the art will recognize that changes may be made in form and detail without departing from the spirit and scope of the invention.

Claims

1. A heater device, comprising:

an outer container formed from a vapor impervious material and having a quantity of heat generating material therein;

a second container positioned proximate the outer container and having an activation material therein; and

a seal on the second container adapted to be opened to transfer the activation material into contact with the heat generating material to generate heat.

2. The device of claim 1, wherein the seal includes a strip detatchably mounted on the second container and having an end extending through the outer container, whereby movement of the end opens the seal.

3. The device of claim 1, wherein the seal includes a valve on the second container that is operable to be opened through the outside container.

4. The device of claim 1, wherein the seal includes an activator comprising a sharp element positioned to pierce the wall of the second container.

5. The device of claim 1, wherein the second container includes a rigid side and a flexible side, and the seal is a score cut into the rigid side that is adapted to rupture upon bending to open the second container to allow the activation material to enter the outer container to react with the heat generating material.

6. The device of claim 1, wherein the second container is formed by a wall inside the outer container to thereby divide the outer container into the outer container and the second container.

7. The device of claim 6, wherein the second container further contains sufficient air to break the wall upon application of pressure on the outer container proximate the second container.

8. The device of claim 1, wherein the heat generating material is a mixture of calcium oxide, polyethylene glycol and zeolite.

9. The device of claim 8, wherein the activation agent is water.

10. The device of claim 8, wherein the amount of calcium oxide ranges from about 30 to about 70 weight percent, the amount of polyethylene glycol ranges from about 15 to about 35 weight percent, and the amount of zeolite ranges from about 15 to about 35 weight percent, based on the total weight of heat generating material.

11. The device of claim 10, wherein the amount of water ranges from about 75 to about 125 weight percent, based on the total weight of heat generating material,

12. The device of claim 1, wherein the outer container is sized to cover two sides of a MRE.

13. The device of claim 1, wherein a pair of heater devices are positioned on a MRE, with one of the pair on each side of the MRE.

14. The device of claim 13, wherein the MRE and the pair of heater devices are positioned inside a container.

15. The device of claim 1, wherein the outer container is sized to cover a tray.

16. A heater device, comprising:

an outer container formed from a vapor impervious material and having a quantity of heat generating material therein comprising calcium oxide ranges from about 30 to about 70 weight percent, the amount of polyethylene glycol ranges from about 15 to about 35 weight percent, and the amount of zeolite ranges from about 15 to about 35 weight percent, based on the total weight of heat generating material;

a second container positioned proximate the outer container and having an activation material therein comprising water in an amount ranging from about 75 to 125 weight percent, based on the total weight of heat generating material; and

a seal on the second container adapted to be opened to transfer the activation material into contact with the heat generating material to generate heat.

17. The device of claim 16, wherein the outer container is sized to cover two sides of a MRE.

18. The device of claim 16, wherein a pair of heater devices are positioned on a MRE with one of the pair on each side of the container.

19. The device of claim 18, wherein the MRE and the pair of heater devices are positioned inside a container.

20. The device of claim 16, wherein the outer container is sized to cover a tray.