High Efficiency Combustion Stove
The invention is a stove system that is portable, has a double walled external structure for the passage of air used in combustion of the fuel, which air also maintains the external surface at a cool enough temperature that it can be touched, and which air flow prevents the waste of heat laterally to the ambient air from a hot outer surface. This increases cooking efficiency, because almost all heat that reaches the air flow between the two walls is drawn right into the combustion chamber in the form of preheated air by reason of the chimney effect. Thus almost no heat can escape the outside wall except by reaching the cooking pot bottom and pot sides after passing out the cover vents as exhaust. An internal heat concentrator ring improves the overall efficiency of the burner. The stove is preferably powered with coal, and uses about half as much coal as a conventional coal fired stove resulting from cooking efficiency. Provision is made for generation of electrical energy from the excess stove heat. Additionally, special thermally designed cook pots add to the stove system to decrease food cooking time while reducing the fuel required.
The present application continues in part from a patent application and claims the benefit thereof from U.S. patent application Ser. No. 12/005,212 filed Dec. 27, 2007, and claims the filing dates thereof as to the common subject matter therewith.
BACKGROUND OF THE INVENTION1. Field of the Invention
The present invention relates to the general field of heating apparatus, such as stoves for cooking. More specifically, it concerns a stove that combines cooking with a combustion source of heat such as coal and very high efficiency in doing so. In fact, the efficiency is so high that consumption of coal in the invention is a little more than half of that in prior art coal fired stoves. The invention is further distinguished from prior art coal fired stoves by being portable and cool enough to hold with bare hands. The efficiency and cool outer surface both result from a double walled exterior structure through which all combustion air is ingested.
The present invention also solves the problem that is prevalent in many parts of the world that rely on solid fuel open flame cook stoves of not having any means of effectively generating electricity for use in lighting and battery charging of small devices such as radios. The incorporation of the thermo-electric generator module into the stove to generate electricity while cooking solves this problem.
The goal of the present invention is to reduce the use of fuel used for cooking and thus aid in the reduction of emissions effecting both climate change and health. The design of a new more efficient cookware to be used with the stove adds to this goal of overall fuel economy.
2. Description of the Prior Art
The art and science of cooking goes back many thousands of years. Art work by cavemen shows knowledge of cooking with fire. When coal was discovered, a highly concentrated combustible fuel source that provided very high temperatures with slow fuel consumption became available. Over time, it was learned that using coal for cooking dictated construction of cooking apparatus from materials that could withstand high temperatures, such as iron and steel.
But iron and steel have two significant drawbacks when viewed in the context of the present invention. First of all, they readily absorb radiated and conducted heat, and in turn radiate that heat to the ambient atmosphere. Second, they make the cooking apparatus very heavy. The result is significant wasteful loss of heat that is intended for cooking, and essentially no portability.
It is well known that hot air is less dense than cold air. This causes hot air such as created by a combustion source to rise. In a closed structure containing a heat source and having openings at the bottom and at the top, a tower of rising air is created. This phenomenon is known as the chimney effect.
Another well known physical principle is that the velocity of a gas such as air passing through a walled structure such as a cylinder increases as the cross section of the structure decreases. Thus if the structure is a cylinder, as its diameter decreases, the velocity of the air increases. The presence of a throat, or narrowed cross section, creates what is known as a venturi.
It is known in the prior art to make heat containing structures with a double walled construction. Two examples of that are U.S. Pat. Nos. 6,761,160 and 5,203,316. The latter is a double walled oven. Once, the double walled construction was in part done to make the outer wall cooler to the touch, U.S. Pat. No. 5,921,229. But so far as is currently known to the present inventors, the combination of chimney effect, a venturi, and a double walled construction has never been employed in a stove to increase the efficiency of the heating or cooking. Efficiency is increased because the combustion chamber is surrounded by a double walled structure through which all the combustion air moves, preheating it, and preventing the loss of nearly all the heat from escaping laterally. Rather nearly all heat generated by combustion is radiated to the bottom of the cooking pot or exhausted along the pot's walls to heat it by conduction.
It is documented in the prior art that waste heat can be used to generate electricity, US Patent Application, Publication No. 20060016446, from a furnace and that the technology to do so has been shown in U.S. Pat. No. 5,892,656 for a thermoelectric module.
SUMMARY OF THE INVENTIONBearing in mind the foregoing, it is a principal object of the present invention to combine the principles of the chimney effect, a venturi, and a double walled construction to both increase the heating efficiency and maintain the outer wall of a stove cool enough to touch.
It is a related object of the present invention to use the increased efficiency to economize on the consumption of fuel. Given that an efficient combustion cooking apparatus will necessarily be completely enclosed making it difficult or almost impossible to add fuel during the cooking of a meal, it is a further related object of the invention to employ the efficiency of the present invention to increase the cooking time available for a given amount of fuel.
It is an object of the present invention to include a provision for adding fuel during a long cooking time period by the use of a pellet fuel addition chute which does not require the removal of any cooking pots.
It is another object of the present invention to employ the efficiency and relatively cool outer wall of the present invention to make the apparatus portable, even movable when in use.
An additional object of the present invention to make the apparatus easy to clean by providing an open bottom through which expended fuel can drop, and with a grate disposed at the bottom of a handle equipped removable bucket to readily dump out remaining expended and unexpended fuel.
It is another object of this invention is the use of a chimney on the upper face of the fuel grate to further improve the combustion of the fuel and add to the efficiency of the stove. A further object of this invention is to have a heat concentrator ring disposed above the combustion area such that it focuses the heat to the bottom of the cook pot and improves the heat transfer to the thermo-electric heat collection pipe below it.
Other objects and advantages of the present invention will apparent to those skilled in the art upon consideration of the following descriptions and the appended drawings.
In accordance with a major aspect of the present invention, there is provided a cooking apparatus that is portable, has a double walled external structure for the passage of air used in combustion of the fuel, which air also maintains the external surface at a cool enough temperature that it can be touched, and which air flow prevents the waste of heat laterally to the ambient air from a hot outer surface thereby contributing significantly to cooking efficiency of the apparatus. Basically almost all heat that reaches the air flow between the two walls is drawn right into the combustion chamber in the form of preheated air by reason of the chimney effect. Thus almost no heat can escape the outside wall except by reaching the cooking pot bottom and pot sides after passing out the cover vents as exhaust as intended. The device also includes an externally adjustable air flow regulator disposed within the double wall structure. The stove is preferably powered with coal, and uses approximately half as much coal as a conventional coal fired stove because of its cooking efficiency.
More specifically the structure of the invention is comprised of an outside cylindrical wall, an inside wall in the shape of a truncated cone, a bottom having a large opening in the center, and a vented removable cover. Combustion air is drawn in a multiplicity of rectangular ports from the chimney effect of the combustion further down line. The air passes between the outside wall and cone shaped inside wall after entering the ports. This preheats the air, but it still keeps the outside wall cool enough to handle with bare hands.
The cover includes a multiplicity of vents, from which hot air is exhausted. The cover is an annular ring with a large open center is where the bottom of a pot containing food is exposed to the radiation of the fire and the hot air inside the stove. The hot air then exits the vents and heats the outside of the walls of the pot. The exhaust air flow can be regulated by the sliding dampers placed along the rim of the exhaust vent cover. Disposed within the cone is a removable bucket described next.
The removable bucket is comprised of a tapered portion at its top and a lower cylindrical portion. The cylindrical portion is perforated by a plurality of apertures. When the removable bucket is disposed in the stove, a part of the cylindrical portion projects beneath the bottom of the cone. The apertures are thus exposed to the air flow between the outside wall and the cone. At the intersection of the tapered portion and the cylindrical portion of the bucket is disposed a grate. The grate supports a combustible fuel such as coal in the air flow that passes through apertures. The grate represents the narrowest cross section of the entire route of air flow through the apparatus, and thus acts as a venturi, which increases the temperature at the point of combustion.
The bucket additionally has riser tabs placed about its circumference to which a narrow support shelf is affixed. This support shelf is to provide a stable platform for the heat concentrator shield and to make a tight fitting closure between the fire box and the inner stove wall. Said shield is a concave dished metal plate with an opening in its center through which the combustion heat is concentrated. This shield also acts as a funnel in the re-fueling process by directing the fuel pellets to the fuel grate in an even manor.
The stove is also optionally fitted with a thermo-electric generator (TEG) module which is capable of producing sufficient power to charge a battery which in turn can provide useful energy for lighting, cell phone recharging, radio operation and the like.
The heat collection pipe of the TEG is inserted into an opening disposed in the side of the stove at a height above the rim of the fire box and below the underside of the heat concentrator ring. A fixture on one of the support tabs of the fire box is used to secure the heat transfer pipe of the TEG unit. A ceramic bushing is inserted in through the walls of the stove through which the TEG heat pipe is inserted and remains thermally insulated from the stove walls. The output of the TEG is plugged into its control box which is mounted on the stove platform base.
The stove base provides a means to support the control box whose function is to regulate the battery charging and the power distribution as well as provide operational status indicators. Additionally the stove base provides a more stable base for the stove, if required, as well as adding a safety factor in the event that hot ash falls out the bottom.
The stove system incorporates specially designed cookware which takes full advantage of the stove design. The pots have concentric metal rings protruding from their bottom such that the rings act as heat absorption and transmission devices. The pots have ears on the periphery of the pot to allow for the pot to nest inside the heat chamber of the stove to maximize the heat transfer.
Various other objects, advantages, and features of the invention will become apparent to those skilled in the art from the following discussion taken in conjunction with the appended drawings, in which:
As required, detailed embodiments of the present invention are disclosed herein; however, it is to be understood that the disclosed embodiments are merely exemplary of the invention which may be embodied in various forms. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a basis for the claims and as a representative basis for teaching one skilled in the art to variously employ the present invention in virtually any appropriately detailed structure.
Reference is now made to the drawings, wherein like characteristics and features of the present invention shown in the various figures are designated by the same reference numerals.
In summary, the invention is a cooking apparatus that is portable, has a double walled external structure for the passage of air used in combustion of the fuel, which air also maintains the external surface at a cool enough temperature that it can be touched, and which air flow prevents the waste of heat to the ambient air from a hot outer surface thereby contributing significantly to cooking efficiency of the apparatus. The device also includes an externally adjustable air flow regulator disposed within the double wall structure. The stove is preferably powered with coal, and uses approximately half as much coal as a conventional coal fired stove because of its cooking efficiency. The stove has an electrical generator module that converts the heat within the stove to electricity for charging a battery system to provide for useful work. Additionally the stove incorporates specifically designed cookware to take advantage of the stoves design and add to its overall fuel and cooking efficiency.
Turning to
FIG. 9C—The combustion grate 48 is a concave perforated metal with a chimney like cylinder 80 device placed in the center of the grate which aids in the even distribution of the fuel pellets and acts as a true chimney to improve the air flow through the fuel and direct the heat in a more concentrated column.
While the invention has been described, disclosed, illustrated and shown in various terms or certain embodiments or modifications which it has assumed in practice, the scope of the invention is not intended to be, nor should it be deemed to be, limited thereby Such other modifications or embodiments as may be suggested by the teachings herein are particularly reserved, especially as they fall within the breadth and scope of the claims here appended.
Claims
1. A stove comprising: a double walled exterior having at least one port for drawing combustion air into a passageway between the walls; a bottom attached about its periphery to the double walled exterior; a combustion chamber in communication with the passageway to receive combustion air there from, the chamber being surrounded by the double walled exterior and passageway to minimize loss of heat laterally to ambient air and increase heating efficiency and containing a grate to support combustible fuel; and a cover to support a cooking container and allow venting of exhaust gases.
2. The stove of claim 1 which further comprises a removable bucket concentric with and disposed within the double walled exterior.
3. The stove of claim 1 in which the grate is disposed within the removable bucket and at the bottom of the combustion chamber wherein the grate forms a combustion air flow venturi to increase heating temperature.
4. The stove of claim 1 in which the cover further comprises: an annular ring having a large open center, the open center being covered when the stove is in use by a cooking container to heat it; and the venting occurring through at least one vent from which heated air exits the stove adjacent sides of the cooking container to further heat it.
5. The stove of claim 1 which further comprises a substantial opening in the center of the bottom of the stove suitable for removal of products of combustion such as ash, and which is substantially sealed off during use of the stove by its placement on a flat horizontal surface.
6. The stove of claim 1 in which the interior of the double wall exterior is shaped as a truncated cone having its largest diameter at the top, and in which the removable bucket is comprised of a tapered portion at its top and a lower cylindrical portion, the cylindrical portion being perforated by at least one aperture, and the tapered portion fitting snugly in the lower portion of the truncated cone such that the cylindrical portion projects beneath the bottom of the truncated cone and into the passageway and the at least one aperture is immersed in combustion air flow in the passageway.
7. The stove of claim 4 in which the grate is disposed at an intersection of the tapered portion and the cylindrical top of the air inlet portion of the removable bucket on tabs projecting into the bucket.
8. The stove of claim 1 which further comprises an externally adjustable air flow regulator disposed within the passageway.
9. The stove of claim 8 in which the externally adjustable air flow regulator comprises a stationary horizontal annular plate which includes a plurality of perforations and an adjustable horizontal annular plate having an adjusting tab that projects through a slot in an outer surface of the double walled exterior and having a plurality of perforations wherein a number of perforations in the stationary portion equals a number of perforations in the adjustable portion.
10. The stove of claim 1 which is sized to be portable even in use and which is cool enough in use to be carried with bare hands because of the combustion air flow in the passageway.
11. A stove comprising: an outer wall having at least one port for drawing in combustion air; a bottom attached about its periphery to the outer wall; an inner wall disposed within and substantially concentric with the outer wall, forming between the outer wall and the inner wall a passageway for combustion air flow, the inner wall surrounding a combustion chamber, the combustion air flow in the passageway minimizing heat loss and increasing heating efficiency; a removable bucket concentric with and disposed within the inner wall; a grate disposed within the removable bucket and at the bottom of the combustion chamber for supporting combustible fuel and forming a combustion air flow venturi increasing heating temperature; and an annular ring cover having a large open center, the open center covered when the stove is in use by a cooking container to heat it, and the annular ring having at least one vent from which heated air exits the stove adjacent sides of the cooking container to further heat it.
12. The stove of claim 11 in which the inner wall is shaped as a truncated cone with the largest diameter as the top.
13. The stove of claim 11 which further comprises a substantial opening in the center of the bottom of the stove suitable for removal of products of combustion such as ash, and which is substantially sealed off during use of the stove by its placement on a flat horizontal surface.
14. The stove of claim 11 in which the removable bucket is comprised of a tapered portion at its top and a lower cylindrical portion, the cylindrical portion being perforated by at least one aperture, and the tapered portion fitting snugly in the lower portion of the truncated cone of the inner wall such that the cylindrical portion projects beneath the bottom of the cone of the inner wall and the at least one aperture is immersed in combustion air flow between the inner and outer walls. Tabs along the circumference of the bucket at the juncture of the taper and the cylinder portion that protrude outward to provide stand-off points to center the bucket and to reduce intimate contact with the inner wall of the stove to reduce the heat transfer to the inner wall.
15. The stove of claim 14 in which the grate is disposed at an intersection of the tapered portion and the cylindrical top of the air inlet portion of the removable bucket on tabs projecting into the bucket portion of the removable bucket.
16. The stove of claim 11 which further comprises an externally adjustable air flow regulator disposed within the passageway between the inner and outer walls on the top cap to cover the exhaust ports and acting as a damper as fuel and weather conditions require.
17. The stove of claim 16 in which the externally adjustable air flow regulator comprises a stationary horizontal annular plate which includes a plurality of perforations and an adjustable horizontal annular plate having an adjusting tab that projects through a slot in the outer wall and having a plurality of perforations wherein a number of perforations in the stationary portion equals a number of perforations in the adjustable portion.
18. The stove of claim 11 which is sized to be portable even in use and which is cool enough in use to be carried with bare hands because of the combustion air flow in the passageway.
19. The stove of claim 11 fitted with a thermoelectric generator to produce an electric current during stove use. Said generator consisting of a heat pipe conductor, a hot side heat sink, a thermoelectric module, a cold side heat sink and a means of dissipating the heat from the cold side and a control module.
20. A control module of claim 19 containing the electronic regulation circuit, the storage battery, the output regulator and the input and output attachment means along with the visual status and mode indicators.
21. Cook pot specifically mated and designed to a stove to allow the stove to take full advantage of its design features of increased efficiency and reduced fuel consumption comprising a series of annular rings dispersed around the bottom of the pot to act as heat collectors.
22. The cook pot of claim 21 having heat collector rings of such that the pot bottom and the ring tops are in direct contact with each other to allow for the maximum heat transfer.
23. The Pot of claim 22 wherein said heat collector rings are concentric with each other and having openings spaced around each ring to allow for even heat flow distribution to all rings.
24. The stove of claim 1, having a removable chute for adding fuel to the stove during use without removing the cooking pot.
25. A chute according to claim 24 that is inserted into the top cap of the stove and is positioned over the heat concentrator ring from which fuel pellets may be dispensed.
26. A stove according to claim 25 that has a reservoir for fuel that can be dispensed either manually or via an electro-mechanical control means.
26. A stove of claim 1 with a support means to raise the stove off the ground and allow for ease of use while in operation.
27. The grate of claim 3 where the grate opening size (mesh) is adjusted for the type of fuel being used.
28. The bucket of claim 2 wherein is disposed a support shelf raised above the grate upon which a heat concentrator ring is held. Said concentrator ring serves to direct the heat to the center of the stove and to increase the venturi effect.
29. A heat concentrator ring of claim 3B wherein as a heat sink/radiator provides more even heat release and distribution, said ring has a central opening to focus the heat and is sized to fit snuggly to the interior diameter of the stove, and further, the heat concentrator is concave shaped to allow for proper addition of fuel pellets.
30. The stove of claim 4, wherein exhaust vent regulators attach to said cover of and allow for the selection of vent openings as a means of adjusting the draft.
31. The grate of claim 15 which is placed in its center a perforated, cylindrical chimney section which focuses the draft and allows for proper distribution of the fuel.
Type: Application
Filed: Aug 8, 2011
Publication Date: Mar 15, 2012
Inventors: Larry Hunt (Coral Springs, FL), Henry B. Schur (Hallandale Beach, FL)
Application Number: 13/205,134
International Classification: F24C 1/00 (20060101);