Non-freezing watering dish for animals

A non-freezing dish includes a sealed tube having a heating end and an opposite condensation end configured to be inserted into the ground with the heated end below grade. A phase change material having a gas phase and a liquid phase is sealed in the tube. Heat is absorbed from the ground into the liquid phase to generate a heated gas phase that rises to the condensation end. A condenser conducts the heat to a removable dish and condenses the gas to a cooled liquid phase that is returned to the heated end.

BACKGROUND OF THE INVENTION 
 The present invention relates generally to a heated animal or bird watering
 and/or food dish, and, in particular, to a self-contained dish that is 
 heated without requiring an external power source in order to maintain the
 contents of the dish at a temperature above freezing. 
 Livestock, wildlife, and pets that live outdoors need a consistently 
 available source of fresh water and/or food. When ambient temperatures 
 drop below freezing, some means must be provided to keep their water and 
 food sources from freezing. 
 A number of solutions to the problem of keeping a water source from 
 freezing exist. The simplest, but most impractical, is to provide a 
 running source of water. A common alternative is to use an immersion 
 heater. Immersion heaters are convenient because they are available in a 
 variety of sizes and can be used to heat everything from a large cattle 
 trough holding hundreds of gallons of water to a pet dish holding less 
 than a quart. It is also possible to incorporate a heating element 
 directly into a water dish, such as described in U.S. Pat. No. 5,345,063 
 to Reusche, et al. 
 A disadvantage of most heaters is that they require an external source of 
 power, typically electric power. This means that they are an ongoing 
 expense and often require power lines or extension cords to be run long 
 distances. In addition, power failures are more likely to occur during a 
 winter storm, which is exactly when a source of water is most important to
 livestock, wildlife, and pets. 
 SUMMARY OF THE INVENTION 
 The present invention concerns a non-freezing dish apparatus. The dish is 
 heated by geothermal heat, transferred through a tube, by a phase change 
 (gas-liquid) material from below the frost line to a removable or 
 permanent dish above the earth's surface. Such a dish apparatus includes a
 sealed tube having a heating end and an opposed condensation end. The tube
 is configured to be inserted into ground soil so that the heated end is 
 below the freezing line. A quantity of phase change material having a gas 
 phase and a liquid phase is sealed in the tube. The gas liquid/phase 
 change material is chosen so that the liquid phase pools in the heating 
 end and vaporizes to the gas phase that rises to the condensation end 
 after having absorbed sufficient ambient heat from the soil. A 
 condensation means, such as a plurality of tubular fins or a coil, is 
 positioned in the condensation end of the tube. Such fins or coil capture 
 heat released as the gas phase is condensed to the liquid phase. A 
 removable dish configured to absorb heat from the fins or coil is 
 positioned at the condensation end of the sealed tube. A plurality of 
 ebulators may be sealed in the tube in the heating end to facilitate 
 boiling of the phase change material.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
 The present invention concerns a non-freezing dish for food and/or water 
 that is completely self-contained and requires no supplementary power 
 source. There is shown in the FIG. 1 an embodiment of a non-freezing dish 
 apparatus 10 according to the present invention. This dish apparatus 10 
 takes advantage of the temperature difference that exists between the 
 surface of the ground and soil below the surface. Because soil is a good 
 insulator, a significant temperature differential develops during the 
 winter between the temperature of the air adjacent to the surface and the 
 soil below the surface. The present invention takes advantage of this 
 differential and draws heat energy from below grade to the surface and 
 uses this heat energy to maintain a bowl of water in the liquid state even
 during the coldest weather, in order to provide a source of water to 
 livestock, pets, and wildlife such as birds. The dish apparatus 10 also 
 can be used to prevent food from freezing. 
 The dish apparatus 10 utilizes a sealed tube 11 having a lower heating end 
 12 and an upper condensation end 13 opposite the heating end. The tube 11 
 is configured to be inserted into the ground with the heating end 12 
 extending below a grade 1 into a region of soil 2 that is at least below a
 freeze line 3 for the area of intended use. If desired, the length of the 
 tube 11 can be selected based on the region of intended use. For example, 
 in the southern parts of the United States, where the temperature rarely 
 dips below freezing, the tube 11 does not need to be as long as it does 
 for use in northern regions where the ground may be frozen solid in a 
 region 8-12" deep for prolonged periods of time. The heating end 12 is 
 shown as being rounded, but could be of any suitable configuration such as
 pointed. 
 A predetermined quantity of a phase change material 14 that readily changes
 between a gas phase and a liquid phase is sealed in the tube 11. The phase
 change material 14 is chosen so that when the tube 11 is oriented 
 approximately vertically and pushed into the soil, a liquid portion 14a of
 the phase change material 14 pools in the heating end 12 of the tube with 
 a gas portion 14b above, and the gas pressure in the tube 11 will be the 
 same at the condensation end 13 as at the heating end. The tube 11 is 
 formed of a suitable heat conducting material heat such that energy in the
 soil region 2 surrounding the heating end 12 will transfer through the 
 wall of the tube 11 and will heat the liquid portion 14a of the material 
 14. As the temperature of the air surrounding the upper condensation end 
 13 of the tube 11 drops, the gas portion 14b will lose heat through the 
 wall of the tube causing the gas pressure to drop. The resultant pressure 
 differential will cause the liquid portion 14a to boil and the resulting 
 heated gas phase will rise to the condensation end 13 of the tube. 
 The condensation end 13, which is cooler than the heating end 12, contains 
 a means for condensing the gas such as a plurality of fins 15. When the 
 rising heated gas contacts the surfaces of the fins 15 it condenses to a 
 cooled liquid phase and gives off heat to the fins. The resulting liquid 
 falls back to the heating end 12 of the tube 11 and the process is 
 repeated. Heat from the condensation is absorbed by the fins 15 and is 
 transferred to a removable dish 16 to heat the contents of the dish. For 
 example, the fins 15 can extend downwardly from a bottom surface of a 
 plate 17 that seals an open top of the tube 11. The dish 16 rests on an 
 upper surface of the plate 17 to receive the heat by conduction. As a 
 result, a liquid for drinking or any food containing moisture placed in 
 the dish 16 will be kept from freezing when the ambient temperature of the
 surrounding air drops. The fins 15 can be of any suitable configuration 
 such as concentric tubes of different diameters as shown in the FIG. 3. 
 If desired, a plurality of ebulators 18 may be located in the heating end 
 12 of the tube 11 to facilitate boiling of the liquid phase change 
 material 14a. The ebulators 18 readily absorb heat from the walls of the 
 tube 11 and can be, for example, conventional carpet tacks. Heat loss 
 through the walls of the tube 11 and through the walls of the dish 16 can 
 be reduced by providing insulation. A sleeve 19 of insulating material can
 be provided around an upper portion of the tube 11 extending just below 
 the freezing line 3. In the embodiment of FIG. 1, additional insulation is
 provided around the removable dish 16 by a surrounding cup-shaped 
 insulating container 20. As best shown in the FIG. 2, a pair of opposed 
 tabs 21 extend from a periphery of a central aperture 22 formed in a 
 bottom wall of the container 20. The tabs 21 are attached to the outer 
 surface of the condensation end 13 of the tube 11 that extends through the
 aperture 22. Thus, the container 20 is spaced from the tube 11 and, 
 consequently, little heat is lost by conduction from the tube to the 
 container. A charging fitting 23 is attached to a side wall of the tube 11
 for initially charging the tube with the phase change material 14 and 
 permitting recharging if required. 
 There is illustrated in FIG. 4 another embodiment of a non-freezing dish 
 apparatus 30 according to the present invention. Like the dish apparatus 
 10 described above, the dish apparatus 30 uses a sealed tube 31 having a 
 heating end 32 and a condensation end 33 opposite the heating end. The 
 tube 31 is configured to be inserted into the ground and extend below the 
 grade 1 into a region 2 that is at least below the freeze line 3 for the 
 area of intended use. A phase change material 34 that readily changes 
 between a gas phase and a liquid phase is sealed in the tube 31. When a 
 liquid portion 34a boils, the resulting heated gas phase will rise into a 
 gas portion 34b at the condensation end 33 of the tube 31. 
 A means for condensing such as a condenser coil 35 is positioned above a 
 closed upper end wall of the tube 31. The condenser coil 35 has an inlet 
 end to which an inlet conduit 35a is connected. The inlet conduit 35a 
 extends downwardly through the upper wall of the tube 31 into the upper 
 portion of the condensation end 33 to receive the heated gas phase. The 
 condensation coil 35 can be formed in a spiral shape, as best shown in the
 FIG. 4, with the inlet conduit 35a at the outer end and an outlet conduit 
 35b connected to an inner end. The outlet conduit 35b extends downwardly 
 through the upper wall of the tube 11 adjacent the heating end 32. As the 
 heated gas phase passes through the coil 35, it contacts the inner surface
 of the coil giving off heat and condensing to a cooled liquid phase. The 
 resulting cooled liquid phase flows out of the coil 35 and is delivered to
 the liquid portion 34a in the heating end 32 of the tube 31 through the 
 outlet conduit 35b. 
 A removable dish 36 is positioned on top of the coil 35 to absorb the heat 
 and keep the contents warm. A charging fitting 37 is attached to a side 
 wall of the tube 31 for initially charging the tube with the phase change 
 material 34 and permitting recharging if required. If desired, a plurality
 of ebulators 38 may be positioned in the heating end 32 of the tube 31 to 
 facilitate boiling of the phase change material 34. A sleeve 39 of 
 insulating material can be provided around an upper portion of the tube 31
 extending just below the freezing line 3. Additional insulation can be 
 provided around the removable dish 36 by a surrounding cup-shaped 
 insulating container 40. The conduits 35a and 35b extend through apertures
 formed in the bottom wall of the container 40. 
 The tube 11 or 31 can be inserted into the ground by forcing it in with 
 downward pressure, where the ground is relatively soft, or by forming a 
 receiving hole much like a typical fence post hole. There is shown in the 
 FIG. 6 an alternate embodiment of the present invention wherein a helical 
 thread 50 is formed on the exterior of the lower end 12 of the tube 11 
 thereby permitting the tube to be "screwed" into the ground by rotation 
 about its longitudinal axis. As an aid to rotation, opposed handles 51 can
 be provided on the exterior of the upper end of the tube 11. The threads 
 50 can be formed of the same material as the tube 11 or a similar suitable
 material to also provide additional heat exchange area to pick up 
 geothermal heat from the ground. 
 The present invention is ideal for maintaining water in a liquid state 
 during cold weather for both domestic and wild animals. For example, a 
 number of the described watering devices could be used in a pen to provide
 water for free range chickens, turkeys, minks, dogs, cats, etc. In 
 addition, the device may be placed close to a bird or squirrel feeder to 
 provide water and draw wild animals closer to a dwelling where they can be
 more easily observed. Accordingly, the present invention may be sized to 
 better fit its intended application. 
 In accordance with the provisions of the patent statutes, the present 
 invention has been described in what is considered to represent its 
 preferred embodiment. However, it should be noted that the invention can 
 be practiced otherwise than as specifically illustrated and described 
 without departing from its spirit or scope.