Patent Application
20090090353
The present application is directed to the field of heating and heat exchange and more particularly to a method and apparatus for a portable self-contained heating vessel having enhanced efficiency and safety features.
A vessel that is capable of self-contained heating, namely a heating vessel which contains the necessary components included there within to heat a substance, is desirable for many outdoor and other uses, including camping and other situations in which many modes of cooking and heating foods and liquids are not readily available or easily performed. The portability of such a self-contained heating vessel enables the vessel to be carried with the user and utilized effectively to heat food, water and other comestibles when needed and without the necessity of packing unwieldy cooking units or having to rely on the inefficiency and inconsistency of a camp fire.
Certain self-heating cups and kettles are known in the prior art, examples of which are described below.
U.S. Pat. No. 4,191,173 to Dedeian et al. describes a self-heating cup including a cup formed of a cylindrical vessel and a hollow carrying handle attached to the vessel containing a liquid fuel reservoir from which fuel in a gaseous state is conducted to a burner located beneath a domed portion of the bottom wall of the vessel.
U.S. Pat. No. 5,690,094 to Sheinfeld et al. describes a gas flame kettle including a housing, a gas burner contained within the housing, a container for the fluid to be heated positioned within the housing and above the burner, and an exhaust duct leading from an area above the burner, through the container, and out of a surface of the housing. Excess heat and combustion gases are exhausted in heat-exchanged contact with fluid in the container via the ducts, for augmented heating of the fluid with simultaneous protection and insulation of the housing.
U.S. Patent Application Publication No. 2004/0011350 to Dowst et al. describes a heating vessel including a chamber having enclosed sides, a thermally conductive bottom end and a top end forming an opening for the introduction and extraction of contents to be heated, the bottom end having an external bottom side. A heater comprising a heat exchanger and a heat source having a heat outlet disposed at a fixed distance from the external bottom side and configured to deliver heat to a central area thereof. The heat exchanger includes a series of thermally conductive radially disposed fins that are coupled circumferentially about the central area of the external bottom side, the fins extending for a fixed distance to encase the heat outlet. A gas flow path is formed to allow intake of air and output of exhaust.
It has been determined that of particular importance in the design of a self-contained heating vessel is the cabability of the vessel to be used in a safe and efficient manner. Accordingly, there is a need for a self-contained heating vessel that offers enhancements in such areas as safety and efficiency.
A method and apparatus for a self-contained heating vessel having enhanced efficiency and safety features is disclosed. In one aspect, the vessel includes a chamber for containing fuel; a burner assembly for burning the fuel; a fuel delivery mechanism that delivers the fuel from the chamber to the burner assembly; and a container disposed adjacent to the heat exchanger assembly, the container including an opening to an interior portion of the container. In other aspects, the vessel includes an ignition assembly operatively connected to said burner assembly and a heat exchanger assembly disposed adjacent to the burner assembly. In another aspect, the vessel further includes a control assembly operatively connected to at least one of the fuel delivery mechanism and the burner assembly, the control assembly including a displacement sensor that monitors a position of the heating vessel and prevents operation of the fuel delivery/burner assembly if the heating vessel is displaced from an intended operating position. In yet another aspect, the fuel delivery assembly further includes a pressure regulator that controls delivery of the fuel to the fuel delivery/burner assembly and maintains a substantially constant heating profile over a varying temperature range.
The invention is described with reference to the several figures of the drawings, in which:
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention that is claimed. It may be noted that, as used in the specification and the appended claims, the singular forms “a”, “an” and “the” include plural referents unless the context clearly dictates otherwise. References cited herein are hereby incorporated by reference in their entirety, except to the extent that they conflict with teachings explicitly set forth in this specification.
A method and apparatus for a self-contained heating vessel is disclosed. Examples of beneficial features and components provided by the various described embodiments of the self-contained heating vessel, discussed in detail below, include: (1) built-in fuel supply; (2) built-in pot or cup; (3) quick and convenient to set up (no pot to attach, no fuel to attach, etc.); (4) easy to operate (no knobs to adjust, no matches needed); (5) one button press on, automatic ignition, easily turned off; (6) turns off automatically; (7) stable; (8) expandable capacity; (9) no exposed flames; (10) low carbon monoxide (CO) output; (11) turns off when tipped or when bottom not placed on a firm surface; (12) inside of pot is smooth (like a standard pot) and facilitates cleaning; (13) wind screen provides wind protection; (14) more efficient than standard camping stove in terms of heat wasted; (15) turns off in over heated condition (e.g., water boils away); (16) a pressure regulator gives the device a constant heating profile over varying temperatures; and (17) lower gas pressure allows use of lighter weight plastic fuel tanks instead of heavy steel ones as typically used in canister stoves.
Referring now to the figures of the drawing, the figures constitute a part of this specification and illustrate exemplary embodiments of the invention. It is to be understood that in some instances various aspects of the invention may be shown schematically or may be exaggerated to facilitate an understanding of the invention.
In the illustrated embodiment, the heat exchanger 202 includes a plurality of protrusions 204 from the base 206 of the heat exchanger 202. These protrusions 204 serve to maximize the available surface area of the heat exchanger 202, thereby maximizing the potential conductive and convective heat transfer to the base of the heat exchanger 202 and eventually to the container 200. One skilled in the art will readily recognize that numerous alternate embodiments of the heat exchanger may be employed such that heat transfer from the heat exchanger 202 to the container 200 is maximized. Furthermore, the container 200 of the present embodiment may take numerous alternate arrangements which maintain the functionality and scope of the present invention. For example, the container 200 may be of varying shape, size and material. In other embodiments, the container 200 may be constructed using a deep draw manufacturing method.
Additionally, the container 200 may be of adaptable size, such that volume extenders 208a may be readily attached to the upper region 208 of the container 200 to increase the available volume of the container 200. The volume extenders 208a may attach to the upper region 208 of the container 200 using a variety of readily available mechanical fastening means, as understood by one skilled in the art, including but not limited to frictional fits or threaded fastening arrangements. The volume extenders 208a provide the ability to adjust capacity of the cup or pot (for example, no extender, 14 oz, extended to 24 oz and further extended to 32 oz). This allows the user to choose the necessary size for their trip (depending on number of people, type of food desired, etc.) with the same base assembly along with the required extenders. Further, the extenders allow the device to be more stable when only heating 8 oz of soup or chocolate versus heating a 32 oz meal. This provides safety in a tent or uneven surface or windy conditions. The user does not have to sacrifice the benefits of a lightweight and small device to get a useful device for larger needs. The extenders are leak proof when attached to pot rim and are made of material that can withstand boiling temperatures.
In heat transmissive communication with the heat exchanger assembly 102 is a fuel delivery/burner assembly 104. In the present illustration, the fuel delivery/burner assembly 104 includes a perforated burner plate 402. The perforated burner plate 402 includes a plurality of perforations capable of delivering pressurized fuel stored in a gas tank 414. The perforations of the perforated burner plate 402 are sized and orientated to deliver a maximum amount of heat, by way of a flame, to the heat exchanger 202, while simultaneously providing a sufficient amount of heat to adequately heat the contents of the deep drawn container 200. Additionally, the sizing and arrangement of the perforations of burner plate 402 is such that the generation of excessive carbon monoxide and carbon dioxide is minimized, thereby allowing the use of the heating vessel 100 in a contained environment.
Associated with the burner plate 402 is a burner body 404, wherein said burner body 404 is mechanically fastened to the burner plate 402. Attachment of the burner plate 402 to the burner body 404 may be accomplished using a variety of means including brazing, soldering, welding or alternative mechanical fastening means. Additionally, one skilled in the art will readily recognize that the burner plate 402 and burner body 404 may be manufactured as a single assembly using a variety of manufacturing means such as deep drawing and stamping. Manufacturing the burner plate 402 and burner body 404 as a single assembly thereby prevents the need for mechanical fastening means and prevents potential leaks in the interface between the burner plate 402 and the burner body 404. The burner plate 402 and burner body 404 may be manufactured form a variety of suitable materials including but not limited to brass alloys, copper alloys, aluminum alloys or steel alloys, and any combination thereof.
Tangentially associated with the burner body 404 is an orifice assembly 406. The orifice assembly 406 may be manufactured from a compatible material as the burner plate 402 and burner body 404 such that the interface joint between the orifice assembly 406 and the burner body 404 may be mechanically fastened. Suitable fastening means include but are not limited to brazing, silver soldering or friction welding. The orifice assembly 406 allows for the mixing of combustion air and a compressed fuel thereby allowing a partially aerated fuel mixture within the burner body 404. The pressurized fuel, stored in a gas tank 414, is delivered to the orifice assembly 406 via a gas delivery tube 412. The gas delivery tube may be manufactured from a variety of suitable materials compatible for deliver of the compressed fuel. For example, the gas delivery tube may be manufactured from a copper allow or a plastic composition. The gas tube 412 may be flexible in nature, readily allowing assembly of the heating vessel 100, or may be rigid in nature.
Compressed fuel delivered to the orifice assembly 406 may be delivered at a controllable pressure, such that burner efficiency is maintained irrespective of the pressure of the compressed case within the gas tank 414. Delivery pressure of the compressed gas from the gas tank 414 may be maintained by a pressure regulator 416 located between the gas tank 414 and the orifice assembly 406. The pressure regulator 416 may be fixed, thereby delivering a constant pressure to the orifice assembly 406 or may be variable such that a user may selectively alter the delivered pressure of the compressed gas based upon the users demands. Furthermore, the pressure regulator 416 may be altitude compensating, such that gas pressure is varied based upon the operating altitude of the heating vessel 100. In light of this, relatively constant combustion rates and flame sizes may be maintained at a burner unit (see, for example burner plate 402 and burner body 404 of
In still another embodiment, pressure is maintained at low temperatures by heating the gas tank 414. In some embodiments, this is accomplished by directing heat exhaust from the burner assembly 104 to flow around the gas tank 414. In another embodiment, a conductive element (not shown) may be provided to conduct heat from the burner assembly 104 to the gas tank 414. In one embodiment, the conductive element is heated using exhaust gases. In another embodiment, the conductive element is heated using flame from the burner.
Further, with respect to carbon monoxide output, ANSI standard Z21.72 allows for 800 ppm. Many stoves exceed this and, presumably, are not ANSI compliant. When flames hit a metal surface they quench (go out) and produce unburned fuel (inefficient) and CO. By using a low flame height and keeping the power output low, the device of the present embodiment mitigates the production of unburned fuel and provides low CO output. The pressure regulator allows for this constant flame height without allowing the user to turn up the flame height to unsafe levels. The design of the present embodiment of the invention provides for a much lower CO output than even the ANSI provides for a more compact (vertically) design, which is important for stability.
In one embodiment, a vessel of the present invention utilizes butane only (no added propane), thus the lower gas pressure allows the use of a lighter weight plastic fuel tank versus the heavy steel ones required for canister stoves. Standard canister stoves generally have no regulator and have flames varying with temperature. They also use propane mixed with the butane for fuel that increases the pressure at low temperatures.
The gas tank 414 may be a sealed unit pre-filled prior to purchase of the heating vessel 100 or in the alternative may allow subsequent refilling by a user upon exhausting of the initial supply. In the illustrated embodiment, the gas tank 414 includes a refill port 418 capable of mating to an external fuel supply (not shown) for refilling of the compressed gas tank 414. Furthermore, the gas tank 414 may be manufactured from a variety of suitable materials, including but not limited to steel or aluminum alloys or a plastic or phenolic composition. Selection of materials may be based upon the anticipated operating conditions of the heating vessel as well as the anticipated gas pressured which the gas tank 414 contains.
The fuel delivery/burner assembly 104 is connected to a operation control assembly 106 capable of both igniting the burner unit of the fuel delivery/burner assembly 104 as well as shutting off the burner unit in the event that the flame of the fuel delivery/burner assembly 104 is extinguished or fails to ignite. This prevents the escape of unburned fuel gas, which can be an explosion hazard. In another embodiment, the heat control assembly also turns off the fuel delivery/burner assembly when the contents of the cup (e.g. water) reaches a certain temperature or if the contents are boiling. This feature is performed by a mechanical temperature detection method or by steam detection. Possibilities include heat passing along a bimetallic part with temp difference detection and/or rate detection via a rising thermostat, as further discussed below. The structural components are in communication with the gas valve to control delivery of gas to the fuel delivery/burner assembly accordingly.
In another embodiment, the operation control assembly 106 extinguishes the fuel delivery/burner assembly 104 in the event that the heating vessel 100 is displaced from an intended operating position. Safety Features and components of the operation control assembly 106 that prevent operation of the fuel delivery/burner assembly are discussed below (see e.g. heat control assemblies and tilt monitor assembly referenced with respect to
The operation control assembly 106 includes an igniter 602, capable of being depressed by an ignition button 604, to deliver a spark to the burner plate 402 region. In the present illustrated embodiment, the igniter 602 may be a spring loaded piezo igniter having a structure that would be understood by one skilled in the art. The spring loaded piezo igniter generates a high voltage which is delivered via the piezo igniter transmission line 620 to the burner plate 402 region. The transmission line 620 of the piezo igniter 602 may terminate in a spark gap, wherein a spark can jump between a conductor in the piezo igniter transmission line 620 and the burner plate 402 assembly.
Actuation of the piezo igniter 602 is accomplished using the ignition button 604. Additionally, the ignition button 604 actuates a gas control system valve 608 upon an initial depressing of the ignition button 604, such that the gas control valve 608 allows for delivery of a compressed fuel from the gas tank 414 to the orifice assembly 406. Actuation of the gas control valve 608 is accomplished via an actuating rod 606 associated with the ignition button 604 and the gas control valve 608. One skilled in the art will readily recognize that numerous alternative gas control valve 608 arrangements may be utilized with the heating vessel of 100. Furthermore, the actuation of the gas control valve 608 during operation of the ignition button 604 may be accomplished using a variety of mechanical means as understood by one skilled in the art. For example, the piezo igniter 602, gas control valve 608 and ignition button 604 may be a discrete sealed unit. In the alternative, the gas control valve 608 may be manually controlled by an operator, wherein an operator opens the gas control valve 608 prior to the depressing of the ignition button 604.
In the presently described embodiment, a heat control assembly 610 is additionally associated with the ignition button 604. The heat control assembly 610 of the present embodiment is further in thermal contact with the container 200, such that the temperature of the container 200 may be monitored by the heat control assembly 610. In the event that the temperature of the container 200 exceeds a predetermined operating parameter, the temperature control assembly 610 operates the actuating rod 606 to close the gas control valve 608, thereby extinguishing the flame at the burner plate 402. Control of the gas control valve 608 by the heat control assembly 610 prevents the overheating of the heating vessel 100. Additionally, the temperature control assembly 610 may further include a tilt monitor mechanism that monitors the tilting of the device and extinguish the fuel delivery/burner assembly accordingly when the tilt monitor mechanism measures a degree of tilt that exceeds a predetermined limit, as further discussed elsewhere herein.
In another embodiment, the temperature control assembly 610 may be a bimetallic switch. The bimetallic switch includes an assembly of two distinct metals, each of which has a different coefficient of expansion. Upon heating of the container 200 by the fuel delivery/burner assembly 104 the bimetallic switch is gradually heated. Heating of the bimetallic switch thereby causes the two metals of the bimetallic switch to gradually expand as governed by their individual coefficient of expansion. The rate of expansion, as dictated by the desired maximum temperature of the container 200, may be utilized in determining the appropriate displacement of the bimetallic switch. Temperatures exceeding this predetermined maximum temperature will result in movement of the bimetallic switch beyond the operating displacement, thereby actuating the actuating rod 606 and closing the flow of gas through the gas control valve 608. The flame at the burner plate 402 is therefore extinguished, and the temperature of the container 200 drops. Once the temperature of the container is below the maximum threshold temperature of the bimetallic switch, the gas control valve 608 may once again by actuated by the actuating rod 606 upon operating of the ignition button 604. One skilled in the art will readily recognize that control of the gas control valve 608 based upon container 200 temperature may be accomplished using a variety of acceptable alternative means. The illustration of a bimetallic switch, therefore, is not intended to be limiting of the acceptable scope of suitable alternatives for use as a temperature control assembly 610.
Associated with the heat exchanger assembly 102, fuel delivery/burner assembly 104 and the operation control assembly 106 is the housing assembly 108. This housing assembly 108 may take numerous forms, manufactured from a variety of suitable materials, such that the heat exchanger assembly 102, fuel delivery/burner assembly 104, and operation control assembly 106 are properly orientated. In one embodiment the housing assembly 108 may be manufactured from, but not limited to, a plastic or composite material.
Surrounding the container 200 is a cup lip 802. The cup lip 802 is sized and orientated to allow delivery and removal of the contents of the container 200 in an efficient manner. Additionally, the cup lip of the illustrated embodiment serves to locate a multipart shell or chassis 804. This multipart chassis 804 serves to orientate the components of the heat exchanger assembly 102, fuel delivery/burner assembly 104 and operation control assembly 106 while simultaneously providing a cosmetically appealing surface. Due to the heat production of the fuel delivery/burner assembly 104, the multipart chassis 804 may include an insulating region, which aid in maintaining a comfortable outer surface temperature of the heating vessel. This insulating region may include, but is not limited to, the use of insulating materials such as fiberglass or aramid fibers, may be a suitable sized air gap or any combination thereof. Further, the shell 804 may include shielding components to keep flames from being exposed and to provide a wind screen, thereby enhancing safety of the device.
In communication with the multipart chassis 804 is a handle assembly 806 sized and orientated for use by a user. Disposed on the handle assembly 806, in the present embodiment, is a safety switch 810 which must be engaged prior to operating of the ignition button 604. One skilled in the art will readily recognize that the safety switch may take numerous forms, including a switch that must be depressed prior to operation of the ignition button 604, or a cover over the ignition button 604 that must first be lifted prior to operating the ignition button 604. The safety switch 810 therefore prevents unintended operation of the heating vessel 100.
Disposed along the bottom of the heating vessel 100 of the present illustrated embodiment is a heat shield 808. This heat shield 808 serves to reflect the heat generated by the fuel delivery/burner assembly 104 toward the heat exchanger assembly 102 and aid in maintaining a comfortable exterior operating temperature of the heating vessel 100. One skilled in the art will readily recognize the heat shield 808 may be manufactured from a plurality of suitable temperature resistant materials including but not limited to steel alloys or high temperature composites.
The cup lip 802, multipart cup chassis 804, handle 806 and heat shield 808 may be mechanically or chemically fastened to each other to maintain proper orientation. Mechanical fastening means include, but are not limited to, screws, bolts or engagement tabs. Chemical fastening techniques include but are not limited to glues or thermoplastic welding. One skilled in the art will readily recognize that numerous alternative fastening means are readily available which are acceptable for use with the present embodiment of the invention.
The chassis 1804 houses a button 1604 that is activated by a user to turn on a burner unit (see, for example, burner plate 402 and burner body 404 of
Housed within the chassis is a control mechanism 1606 that is operatively connected to the gas valve 1608. It is also contemplated that the control mechanism 1606 may be operatively connected to the igniter mechanism 1602. In the illustrated embodiment, the control mechanism 1606 is a latch lever. The latch lever 1606 is disposed between the chassis 1804 and the container 1200 and is attached to the chassis 1804 via a pivot 1614. The latch lever is biased in a position via a bias spring 1616. Alternative locations for the bias spring 1616 are shown in
Operatively connected to the latch lever 1606 are control assemblies that engage to shut off the gas valve and to prevent the flow of gas to, and hence prevent operation of, the burner unit. One embodiment of a control assembly includes a boil detect disc 1610, which is illustrated in the figures in the “cold” position. As illustrated, the center of the boil detect disk is fixed to the chassis 1804. The boil detect disc 1610 detects when the contents of the container 1200 are boiling and, upon such detection, engages to move the latch lever 1606 as an actuating arm, wherein the tip 1606a of the latch lever 1606 disengages from button 1604, allowing button 1604 to turn off via return spring 1604b to shut off the gas flow via gas valve 1608.
Another embodiment of a control assembly includes a heat detect disc 1612, which is illustrated in the figures in the “cold” position. As illustrated, the rim of the heat detect disc 1612 is fixed to the latch lever. The heat detect disc monitors temperature and does not allow the latch lever 1606 to latch in the on position unless flame (heat) is detected. This prevents the unit from latching in the “on” position if the flame fails to ignite for any reason. The disc unlatches the latch lever 1606 in the event of the flame extinguishing for any reason, thus disengaging the gas valve and preventing fuel from escaping into the atmosphere.
Yet another embodiment of a control assembly includes a tilt monitor mechanism 1614. In one embodiment, the tilt monitor mechanism is a cam assembly. In another embodiment, the tilt monitor mechanism 1614 includes a pendulum assembly. The tilt monitor mechanism 1614 monitors a tilt angle of the heating vessel 1000 (for example, via a cam assembly or pendulum assembly) and upon exceeding a predetermined tilt angle, the tilt monitor mechanism engages the lever latch 1606 which in turn engages the gas valve 1608 to shut off the gas flow. In still another embodiment, the tilt monitor mechanism is a snorkel and ball disposed in the gas line that shuts off gas flow when tipped. In another embodiment, the tilt monitor mechanism 1614 may also detect whether the heating vessel has been placed on a flat surface. In the event that the vessel is placed on a non-flat surface, or moved from a flat surface (tipped over or lifted up, for example), the lever latch 1606 is engaged, in the manner as noted above, which in turn engages the gas valve 1608 to shut off the gas flow.
Other embodiments of the invention will be apparent to those skilled in the art from a consideration of the specification or practice of the invention disclosed herein. It is intended that the specification and examples be considered as exemplary only, with the true scope and spirit of the invention being indicated by the following claims.
The present application is a continuation-in-part of U.S. application Ser. No. 11/383,683, filed May 16, 2006, which itself claims priority to U.S. Provisional Patent Application 60/731,401, filed Oct. 27, 2005, the contents of both of which are incorporated by reference. The present application claims priority to U.S. Provisional Patent Application 60/731,401, filed Oct. 27, 2005.
| Number | Date | Country | |
|---|---|---|---|
| 60731401 | Oct 2005 | US | |
| 60731401 | Oct 2005 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 11383683 | May 2006 | US |
| Child | 11461237 | US |
