Patent Publication Number: US-2007107715-A1

Title: Apparatus and Method for a Self-Contained Heating Vessel

Description:
RELATED APPLICATIONS  
      The present application claims priority to U.S. Provisional Application No. 60/731,401, filed Oct. 27, 2005, which is incorporated herein by reference. 
    
    
     FIELD OF THE INVENTION  
      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.  
     BACKGROUND OF THE INVENTION  
      A vessel that is capable of self-contained heating, namely a heating vessel which contains the necessary components included therewithin 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.  
     SUMMARY OF THE INVENTION  
      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.  
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      The invention is described with reference to the several figures of the drawings, in which:  
       FIG. 1A  is an exploded view of a self-contained heating vessel according to one embodiment of the invention;  
       FIG. 1B  is an exploded view of the heating vessel illustrating various components of the assemblies of  FIG. 1A ;  
       FIG. 2  is a perspective view of control assemblies of a self-contained heating vessel according to another embodiment of the invention;  
       FIG. 3  is a side view of the heating vessel according to the embodiment of the invention illustrated in  FIG. 2 ; and  
       FIG. 4  is a perspective view of a self-contained heating vessel according to another embodiment of the invention;  
       FIG. 5  is an enlarged perspective view of fuel delivery and operational control assemblies of the self-contained heating vessel shown in  FIG. 4 . 
    
    
     DETAILED DESCRIPTION OF VARIOUS EMBODIMENTS OF THE INVENTION  
      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”, “can” 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.  
       FIG. 1A  illustrates an exploded view of a self-contained heating vessel  100  in accordance with one embodiment of the present invention. The heating vessel  100  includes a heat exchanger assembly  102 , a fuel delivery/burner assembly  104 , a operation control assembly  106  and a housing assembly  108 . Briefly, the heat exchanger assembly  102  provides a mechanism by which heat generated by the fuel delivery/burner assembly  104  during the conversion of a pressurized fuel to a heating flame may be transmitted to the contents of a container. Additionally, associated with the fuel delivery/burner assembly  104  is a operation control assembly  106  capable of providing an initial ignition source for igniting the fuel supplied to the fuel delivery/burner assembly. The operation control assembly  106  may further be used to ensure that the fuel delivery/burner assembly  104  is not extinguished unintentionally during use. Associated with the heat exchanger assembly  102 , fuel delivery/burner assembly  104 , and operation control assembly  106  is the housing assembly  108 . The housing assembly  108  serves to orient the aforementioned assemblies ( 102 ,  104 ,  106 ) in a desired position, provides the structure for the container in which food or liquid is heated, enables the vessel to be comfortably and ergonomically handled by a user, and provides for a cosmetically appealing arrangement.  
       FIG. 1B  is an exploded view of the heating vessel  100  illustrating the various components of the aforementioned assemblies of  FIG. 1A . Addressing the heat exchanger assembly  102 , a container  200  and a heat exchanger (or heat sink)  202  are associated with each other such that heat provided to the heat exchanger  202  may be transmitted to the container  200  via conductive, convective and/or radiative heat transfer. The container  200  is manufactured from a thermally conductive material, such as but not limited to aluminum alloy, steel alloy or conductive plastics.  
      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  208   a  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  208   a  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  208   a  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  FIG. 1B ) of the fuel delivery/burner assembly  104  at varying altitudes. The pressure regulator allows the flames to remain approximately constant in heat output, appearance and height over a varying temperature range (constant output impedance), thereby facilitating low CO output and efficiency over a wide temperature range. The pressure regulator gives the device a constant heating profile for temperatures from approximately 40 F to approximately 120 F. In another embodiment, the device provides a low primary and secondary flame height in a compact small diameter package that is suitable for a portable stove. In the absence of any control mechanism for the fuel flow, the flames would either be too large at high ambient temperatures, or they would be too small at low ambient temperatures. Although the inclusion of a user control knob for adjusting fuel flow is contemplated herein, the inclusion of a pressure regulator allows for the a user control mechanism for fuel flow to be eliminated while still providing the constant heating profile at varying altitudes and temperature ranges.  
      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  FIGS. 2 and 3 ) Further, the device is also designed for enhanced stability because pot integrated into the unit and having a low center of gravity and a wide base yet is still usable as a drinking mug or cup.  
      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.  
       FIG. 2  is a perspective view of control assemblies of a self-contained heating vessel  1000  according to another embodiment of the invention.  FIG. 3  is a side view of the heating vessel  1000  according to the embodiment of the invention illustrated in  FIG. 2 . A container  1200 , into which the food and liquid to be heated is placed, is attached to a chassis  1804  via attachments  1210  (such as spot welds or other attachment mechanisms known to those of ordinary skill in the art) disposed adjacent to a heat exchanger  1202 . The chassis  1804  may include a shield  1808  that may serve as a wind shield and/or may also serve as a heat shield to redirect heat back towards the heat exchanger  1202  and thereby improve efficiency of the system. A shell  1806  is attached to the chassis  1804  to provide a handle for gripping by the user and to provide a cosmetically appealing appearance. Portions of the chassis  1804 , for example shell  1806  and/or windscreen  1808 , may be translucent to allow a user to see whether a flame is on in the vessel while also providing the wind shield and/or heat shield functions noted above.  
      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  FIG. 1B ). The button  1604  has a shaft  1604   a  extending along the chassis  1804  and that is communication with a return spring  1604   b  that returns the button to its pre-activated position after being released by the user. The shaft  1604   a  of the button is operatively connected to a gas valve  1608 . When the button  1604  is activated, the shaft  1604   a  engages the gas valve  1608  (e.g. via a connector arm) to open the valve and allow gas to flow from a gas tank  414  to the fuel delivery/burner assembly  104  (having components as discussed above in reference to  FIGS. 1A  and  FIGS. 1B  and illustrated therein). Activation of the button  1604  also engages an igniter mechanism  1602 , such as a piezo igniter, that ignites the burner unit  402 ,  404 .  
      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  FIGS. 2 and 3 .  
      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  1606   a  of the latch lever  1606  disengages from button  1604 , allowing button  1604  to turn off via return spring  1604   b  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.  
       FIG. 4  is a perspective view of a self-contained heating vessel  2000  according to another embodiment of the invention. The vessel  2000  includes a container  2100  in which foods and liquids to be heated may be placed and including a heat exchanger assembly that facilitates heat transfer from the burner assembly  2200  that is disposed adjacent to the container  2100 . The burner assembly  2200  receives fuel from and is controlled by the fuel delivery and operational control assemblies  2300  (discussed in detail below in reference to  FIG. 5 ) and produces heat that is transferred to the contents of the container  2100 . Further, as illustrated, a transparent covering  2400  may be disposed around or adjacent to the burner assembly and which provides an external view of the burner assembly that enables a user to determine whether the burner is operational (e.g. whether a flame is seen). The covering  2400  may also provide a wind screen function as noted above.  
       FIG. 5  is an enlarged perspective view of the fuel delivery and operational control assemblies  2300  of the self-contained heating vessel shown in  FIG. 4 . Manual control by a user to activate the self-heating operations of the vessel is provided by button  2301  that is operationally connected to the vessel system to initiate delivery of fuel and activation of the burner assembly. Further, as illustrated, a tilt sensor assembly  2310  is in the raised position against the bias of its spring  2312  when the vessel  2000  is resting on a surface (the spring  2312  is shown extending from the tilt sensor foot  2314  all the way up to the chassis  2302 ). When the vessel is tilted or lifted, the tilt sensor assembly  2310  extends to an extended position (downward). At the top of the tilt sensor  2310  is a catch release cam surface  2316  that is angled from a small diameter to a large diameter and that acts on the edge of a lever assembly  2320 , which in turn rotates about a pivot  2330  thereby engaging a gas valve assembly  2340  and shutting off the gas supply to the burner assembly. Thermal sensor assemblies  2350  are shown disposed on the pivoting lever assembly  2320  and are capable of shutting of the gas supply in a similar manner as operationally described above in reference to  FIGS. 2 and 3 .  
      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.