Patent Application
20100154770
1. Field of the Invention
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.
2. Brief Description of the Prior Art
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.
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.
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, 5,775,316, 3,759,164, 5,992,407, 6,439,107 and 6,725,856. 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.
U.S. Pat. Nos. 6,234,064, 6,098,611, D386,936, 4,555,616, 4,353,347 and 4,108,142 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.
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.
U.S. Pat. No. 5,979,428 teaches a retrofitable wind screen for portable stove which is wrapped around the original stove body. This is wrap around wind screen is not study at all to withstand a round bottom vessel.
U.S. Pat. No. 5,315,983 teaches a two piece support ring structure for supporting a wok cooking vessel on top of a burner cylinder of a cooking range. Between these two pieces of ring structure some windows can be formed on the back of the range for exhaust. U.S. Pat. No. 6,832,607 shows an outdoor cook stove with a wind guard of two windows at its back for flame outlet. The top bars of the windows in both U.S. Pat. Nos. 5,315,983 and 6,832,607 are subjected to high temperature flames and thus are the most vulnerable for damage. Besides, these top bars block the flame to reach the wok underneath surface. This blockage is an efficiency loss.
It is the objectives of the present invention to overcome aforementioned drawbacks.
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.
The second 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. To increase cooking efficiency and product life cycle, such openings do not have top bars to block burner flamer from reaching underneath surface of the cooking vessel. 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 9″-13″ in diameter for commonly available woks.
The third 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.
The fourth 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.
The fifth 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.
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.
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:
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 9″ to 13″. 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 underneath 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. It should be noted that 120 and 122 are just slots cut into ring 100. By putting a wok on top of ring 100, windows 120 and 122 are formed between the opened slots and underneath surface of the cooking wok. In this way the ring defines the heating area to the wok. And the flame coming out of windows 120 and 122 continues to heat 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 any harm to the operator.
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.
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 in
To start cooking, high pressure gaseous fuel is supplied through a high pressure regulator. Ejected combustion gas and air mixture from the burner 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 igniter to ignite the flame through top of ring 100.
A second stove embodiment of the present invention is shown generally in
A third stove embodiment of the present invention is shown in
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.
