Abstract:
A portable outdoor stove is provided which includes a burner primarily comprising an outer and inner pieces bolted tightly to form a small gas/air mixture chamber for accepting and maintaining high pressure gaseous fuel, a wind guard of cylinder shape capable of tightly coupled with a cooking vessel and possessing window opening of less than 180° toward its top for exhaust outlet, adjustable means for supporting the burner and positioning flame from burner onto bottom of cooking vessel and supporting means for the wind guard.  
     The burner possesses set of holes capable of directing high pressure combustion flame toward a upper center point concentrating heating power, extremely suitable for heating the bottom of a wok or any round bottom cooking vessel. With an adapter, another set of holes is capable of producing upward and outward spreading flame for flat bottom type cooking vessels. A protection guard can be put around the first wind guard preventing an operator accidentally touching the wind guard during cooking.

Description:
U.S. PATENT DOCUMENTS  
         [0001]    [0001]                                                                   4,062,341   December 1977   Panzarella   126/41   R           5,158,067   October 1992   Dutro et at.   126/39   R           6,234,064   May 2001   Turrel   99/323.9           6,098,611   August 2000   Filmore   126/50           D386,936   December 1997   Stone et al.   D7/332           4,553,524   November 1985   Wheat et al.   126/25   R           4,353,347   October 1982   Seed   126/41   R           5,775,316   July 1998   Jones   126/41   R           4,555,616   November 1985   O&#39;Brien   219/432           5,044,352   September 1991   Lok   126/39   R           5,226,406   July 1993   Reynolds   126/39   R           4,583,941   April 1986   Elperin et al.   41/347                        
         BACKGROUND OF THE INVENTION  
         [0002]    1. Field of the Invention  
           [0003]    The present invention relates to an outdoor cook stove utilizing high pressure gaseous fuel, in particular a stove for domestic or industrial gas cooking using bottled gas, and is suitable for round bottom cooking vessels.  
           [0004]    2. Brief Description of the Prior Art  
           [0005]    There are various attempts for outdoor stove manufacturers to accommodate cooking for round bottom vessels such as a wok. Barbecue equipment makers make wok adapter to sit on top of fire grid. However the fire grid is not powerful enough and the entire structure is not efficient enough for wok cooking. Authentic, restaurant quality oriental wok cooking requires a stove capable of generating more than 100,000 BTU in power. Such power is beyond reach of single ring low pressure gas stoves. In commercial and industrial wok cooker, as partially illustrated in U.S. Pat. No. 5,315,983, either multi-rings or multiple jet burners are used to achieve the necessary power. Another drawback of using low pressure gaseous fuel is its stove being more susceptible to wind during outdoor cooking.  
           [0006]    U.S. Pat. Nos. 5,158,067 and 4,062,341 taught outdoor stove construction for wok cooking. However they share several disadvantages that prevent them from reaching high quality oriental cooking. The first is the low pressure gaseous fuel which prevents their stoves from reaching 100,000 BTU in power. The second disadvantage is the low pressure burner which they utilize does not have center flame heating to the bottom of a wok. As with a bowl shape, it is most important to direct the burning flame toward the bottom of a wok for efficient heat transfer. The disadvantage of not using a center flame is in many burner designs, for example U.S. Pat. Nos. 6,234,064, 6,098,611, D386,936, 4,553,524, 4,353,347. The flame coming out from all these burners spread outward, leaving a sizable center portion of the cooking vessel relying on metal conducting heat back to its center. For a wok, this heat conducting downward to its bottom is extremely inefficient.  
           [0007]    Yet another disadvantage of the aforementioned stove constructions is to allow the flame to extend above the wok along its outside surface. Since wok cooking requires an operator to stay closely and maneuver the wok in different ways, the flame coming out can easily burn and hurt the operator. Such examples can be found in U.S. Pat. Nos. 4,062,341, 6,098,611 and 5,775,316. Because of this reason, the operator is forced to reduce power of the stove to stay safe. For low pressure gaseous stove ranges like in U.S. Pat. Nos. 5,044,352 and 5,226,406, expensive exhaust duct mechanism is built for routing the flame and exhaust away from the operator.  
           [0008]    U.S. Pat. Nos. 6,234,064, 6,098,611, D386,936, 4,555,616 and 4,353,347 taught to have fixed center burner position with respect to bowl shape cooking vessel. Such fixed position defines fixed heating power distribution to the vessel, forcing the operator to frequently toss foods to various locations in order to receive different heating power. Fixed position between stove and wok greatly restricts the freedom for the operator to tilt and rotate the wok for various food items to receive different flame power, which is necessary when the food items are too fragile to be tossed.  
           [0009]    U.S. Pat. No. 4,583,941 taught a burner construction on how to form flame inwardly around an imaginary cylinder. Although the flame is inwardly directed, it still does not heat the center portion of its cooking vessel. Another drawback is that as required by its inward flame, the burner has a bigger chamber for pre-mixed gaseous fuel and air. This big chamber inevitably reduces the mixture gas pressure and hence the power of the burner.  
           [0010]    It is the objectives of the present invention to overcome aforementioned drawbacks.  
         SUMMARY OF THE INVENTION  
         [0011]    The first objective of the present invention is to utilize high pressure gaseous fuel to achieve highest power for wok cooking with simple burner construction to save cost significantly over traditional high power wok cookers with low pressure gaseous fuel.  
           [0012]    The second objective of the present invention is to construct a burner to produce a concentrating inward flame. This flame is directed to the bottom of the cooking vessel (wok) and naturally extends upward along the wok outside surface. In this way heat is first concentrated at the wok bottom and then spread along the outer surface.  
           [0013]    The third objective of the present invention is to construct an outdoor stove with a wind guard ring tightly hosting a wok. A portion of the wind guard has openings close to the wok for directing out the flame and exhaust. It also provides access for burner ignition. This portion is to be positioned away from the operator during operation. The rest portion of the wind guard does not have opening to prevent any flame from extending along its side. The operator is positioned along this side for safe operation. This wind guard defines the heating area to the wok and is sized around 8″-10″ in diameter for commonly available woks.  
           [0014]    The fourth objective of the present invention is to add a second ring outside the first wind guard to prevent the operator from accidentally touching the hot surface of the first wind guard.  
           [0015]    The fifth objective of the present invention is to construct a stove to give complete freedom to the wok operator. The wok is not required to be fixed in position to the stove. The operator can tilt and move the wok in his/her own will at any time in order to achieve best cooking result.  
           [0016]    The sixth objective of the present invention is to construct a burner to maintain high gas pressure within the gas chamber before ejecting for ignition. Maintaining high gas pressure all way through the burner guarantees its rated power delivery.  
           [0017]    The seventh objective of the present invention is to have burner position adjustable within the stove to accommodate both round and flat bottom cooking vessels for optimum heat transfer. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0018]    The invention will now be described in connection with certain preferred embodiments with reference to the following illustrative figures so that it may be more fully understood.  
         [0019]    With specific reference now to the figures in detail, it is stressed that the particular shown are by way of example and for purpose of illustrative discussion of the preferred embodiments of the present invention only. They are presented in the cause of providing what is believed to be the most useful and readily understood description of the principles and conceptual aspects of the invention. In this regard, no attempt is made to show structural details of the invention in more detail than is necessary for a fundamental understanding of the invention. The description together with the drawings should make it apparent for those skilled in the art how the several forms of the invention may be embodied in practice. In the drawings:  
         [0020]    [0020]FIG. 1A is a perspective view of the first embodiment of an outdoor burner constructed according to the present invention showing its burner head with all flame holes inwardly directed.  
         [0021]    [0021]FIG. 1B is a side cross section view of the embodiment of FIG. 1A showing detailed construction of the flame holes all directing toward a center point.  
         [0022]    [0022]FIG. 2A is a perspective view of a first embodiment of an outdoor stove incorporating the embodiment of FIG. 1A, as well as a wind guard ring and an adjustable metal strip for holding the burner.  
         [0023]    [0023]FIG. 2B is a side elevated view of the embodiment of FIG. 2A showing how the burner is bolted on the strip.  
         [0024]    [0024]FIG. 2C is a top view of the embodiment in FIG. 2A showing details of the mounting strip and three supporting legs.  
         [0025]    [0025]FIG. 3 is a perspective view of a second embodiment of an outdoor stove with a second wind guard ring encircling the first ring.  
         [0026]    [0026]FIG. 4A is a perspective view of a second embodiment of an outdoor burner with the inner piece extending over the top of the outer piece.  
         [0027]    [0027]FIG. 4B gives a cross section view of the embodiment of FIG. 4A showing its internal construction.  
         [0028]    [0028]FIG. 5A is a perspective view of a third embodiment of an outdoor burner with adjustable flame direction. This view shows inward flame selection.  
         [0029]    [0029]FIG. 5B is a cross section view of the embodiment of FIG. 5A showing a burner selection for inward flame.  
         [0030]    [0030]FIG. 6A is an alternative perspective view of the embodiment of FIG. 5A showing a burner selection for outward flame.  
         [0031]    [0031]FIG. 6B is a cross section view of the embodiment of FIG. 5A corresponding to FIG. 6A. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0032]    An outdoor burner constructed according to the preferred embodiment of the present invention is indicated generally at  10  in FIG. 1A. The burner  10  includes an outer piece  12  housing an inner piece  14 . Both pieces are tightened together by a bolt  30 , nut  32  and washer  34 . The entire burner can be made by cast iron. Piece  12  generally has a cone like upward and outward inner surface  22  which is to be coupled with outer surface of piece  14  tightly. Bolt  30 , hut  32  and washer  34 , illustrated in FIG. 1B, enforce the tight coupling. The resulting gap  60  does not pass any gaseous fuel out along the slope  22 . The center of outer piece  12  is a hollow airway  52 . Airway  52 ,usually leads to a venturi opening  28  for inlet of mixed gaseous and air. The ratio of gas to air mixture coming from venturi opening  28 , shown in FIG. 2A, through a narrower section  26  to airway  52  can be adjusted by a perforated plate  29 . The structure of the venturi opening and its gas/air inlet ratio adjustment is well known in the art. Their detail drawing are not given here.  
         [0033]    The vertical section of the airway  52  and a section  54  between pieces  12  and  14  form a chamber for the gas and air mixture. The small area  54  formed between outer and inner pieces  12  and  14  insures the mixture to remain in high pressure. From this chamber the mixture is directed through hole  56 . Hole  56  then turns the mixture into holes  44 . From holes  44  the mixture ejects out and combusts. Holes  44  are equally spaced, and have a upward slope of α degree with respect to horizontal plane α can be selected in a wide range and is preferably between 10°-85°. The taller wall  20  of piece  12  serves as an additional wind guard for the combustion flame coming out from holes  44 . Since holes  44  are arranged as inward and upward, combustion flames from individual holes  44  are cone shaped and concentrated to a point above burner  10 .  
         [0034]    [0034]FIG. 2A illustrates an outdoor stove  80  constructed according to the preferred embodiment of the present invention. Although stove  80  is specially designed to handle outdoor cooking using a round bottom cooking vessel, stove  80  is also suitable for flat bottom vessel cooking. Stove  80  includes a preferred burner  10  of present invention. Burner  10  is mounted on a metal bar  130  using the same bolt  30 , nut  32  and washer  34 . Burner  10  directs its flames inward and upward to a concentrating point. This point can be aligned with the bottom of a wok by metal bar  130 . Metal bar  130  has a horizontal section  134 . In the center of  134  a hole is drilled for bolt  30  to come through, better viewed in FIG. 2B. Burner  10  is mounted on  134  and position of the venturi pipe  24  can be adjusted horizontally for convenient inlet of gas pipe  70 . Metal bar  130  also includes two vertical sections  132  and  136  at both ends. These two vertical sections  132  and  136  have slot openings. For example, vertical  132  has a slot  138 . Two bolts  140 ,  142 , two nuts  150 ,  152  and two washers  160 ,  162  are used to fasten the slot  132  to a supporting ring  100 . Similar construction is done on another side  136 . Vertical positioning of the metal bar  130  along ring  100  is accomplished by adjusting the slots with respect to the bolts. In this way the concentrating flame point can always be adjusted to touch the bottom of various woks and other round bottom vessels. The length of section  134  is about the same as the diameter of ring  100 .  
         [0035]    Ring  100  serves multiple purposes. It can support a wok for cooking. A wok can sit right on ring  100 . The diameter for ring  100  is preferably between 8″ to 10″. Ring  100  is constructed as a cylinder shape to house a wok with minimum gap. After heating the bottom of the wok, the concentrated combustion flame is split up along the wok outer surface. Because of small gap between wok and ring  100 , the flame is not able to penetrate out of the gap. Instead, it is forced to use windows  120  and  122  for exhaust purpose. In this way the ring defines the heating area to the wok. Since windows  120  and  122  have limited opening on ring  100 , their openings define limited unsafe area for an operator. When an operator is working away from these openings (windows  120  and  122 ), there is no flame coming up along the outer surface of the wok to cause damage.  
         [0036]    The total opening angle along ring  100  is preferably less than 180° such that no direct wind can blow through burner  10 . In this way ring  100  serves as a wind guard. Ring  100  also supports metal bar  130  for burner  10 . Four holes are drilled for mounting bolts for slots along  132  and  136 .  
         [0037]    Ring  100  is further supported by three legs  110 ,  112  and  114 . Construction for each leg is similar. A bend at  116  for leg  110  is to increase its bottom perimeter to enhance stability of the entire stove  80 . Top end  110 A of leg  110  is welded to a lower position of ring  100 . Legs  110 ,  112  and  114  are preferably spread out in 120°.  
         [0038]    To start cooking, high pressure gaseous fuel is supplied through a high pressure regulator. Ejected combustion gas and air mixture from holes  44  can be ignited by an outdoor igniter through either ring windows  120 ,  122  while a wok is already sitting on top of ring  100 . Alternately, the wok can be temporally moved away for an ignitor to ignite the flame through top of ring  100 .  
         [0039]    A second stove embodiment of the present invention is shown generally in FIG. 3. Since ring  100  prevents flame from burner  10  to reach the operator on the opposite side of windows  120  and  122 , the heat is trapped within ring  100  for the energy to be transferred to a wok. When burner  10  is adjusted to its upper power range, ring  100  may warm up and be hazardous to touch. Although there is little chance for the operator to touch ring  100  because the operation is accomplished by using wok handles at least half foot away from ring  100 , a second ring  200  can still be added outside of ring  100  to protect ring  100  from being reached. Various mounting technique can be used for ring  200 . Three metal pieces  210 ,  212  and  214  are welded upwardly on legs  110 ,  112  and  114 . Piece  210  and leg  110 , piece  212  and leg  112 , piece  214  and leg  114  together define three junction points for ring  200  to rest on. The height of ring  200  is constructed lower than that of ring  100 , preferably half inch. In this way a wok is still supported by ring  100  and exhaust flame can still come out from windows  120  and  122 . Aforementioned features of ring  100  are preserved. Since ring  200  is not heated by flame from burner  10 , it will remain cool during on-going cooking process. An alternate mounting for ring  200  is to weld it directly on legs  110 ,  112  and  114 . Ring  200  does not need to be solid, it can be perforated as long as it can prevent the operator&#39;s fingers to reach in to ring  100 .  
         [0040]    A second burner embodiment of the present invention is illustrated in FIGS. 4A and 4B. Outer piece  412  is below the inner piece  414 . Surface  401  of piece  414  has edge  403  extended covering the top perimeter of outer piece  412 . Bolt  30 , nut  32  and washer  34  clamp gap  405  as minimum between inner and outer pieces  414  and  412 . Gap  405  does not pass gaseous fuel and forces the fuel to go through holes  44 . Because of gap  405 &#39;s function, gap  460 , formed by both upward slopes of inner and outer piece  414  and  412 , does not need to be tight, not as required by the first embodiment illustrated in FIGS. 1A and 1B. However, gap  460  should remain small to maintain a small size of gas/air chamber  454 . Since gap  460  is not required for preventing gaseous leakage, angle β between slope of gap  460  and horizontal plane can be increased up to 90°. In other words, slope of gap  460  can be upward and outward or simply upward.  
         [0041]    A third burner embodiment of the present invention is shown from FIGS. 5A to  6 B. In addition to inward and upward holes  44 , a group of slots  561  are constructed in equal distance along perimeter of inner piece  14 . Slots  561  are connected with slots  56  along outer surface of inner piece  14 . After being tighten down by bolt  30 , nut  32  and washer  34 , slots  561  and slope  22  of the outer piece  12  form holes that can deliver combustion flame outwardly and upwardly. An adapter f6 is added on top of inner piece  14 . Adapter  16  has a flat surface  300  covering surface  40  of inner piece  14 . On perimeter of  300  there are slots  402 . Adapter  16  also include fins  310  bent along surface  42  of inner piece  14 . Flat surface  300  has three slots  322  through which screws  320  tie adapter  16  down with inner piece  14 . Slots  322  and screws  320  also allow relative position of adapter  16  to be adjusted with respect to inner piece  14 . FIGS. 5A and 5B show the adapter in a position blocking slots  561  and directing the combustion flame through holes  44  inwardly and upwardly. In this way gaseous fuel is directed from slots  56  to holes  44 .  
         [0042]    Before cooking, screws  320  can be loosen and position of slots  402  can be adjusted to align with slots  561  of inner piece  14 . In the mean time, fins  310  block holes  44 , preventing combustion fuel from coming out from holes  44 . Instead, the combustion fuel is directed through slots  56  and then  561  upwardly and outwardly. With this upward and outward combustion flame, the burner can be used for flat cooking vessel, for example, deep fry turkey pan. Again the height of the burner against the flat bottom of the cooking vessel can be adjusted by metal bar  130 .  
         [0043]    It will be evident to those skilled in the art that the invention is not limited to the details of the foregoing illustrative embodiments and that the present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive. The scope of the invention will be indicated by the appended claims rather than by the foregoing description. And all changes, which come within the meaning and range of equivalency of the claims, are therefore intended to be embraced therein.