阅读说明：本技术 具有可变火焰速率的雾化燃烧器 (Atomizing burner with variable flame rate ) 是由 安德鲁·D·巴宾顿 胡安·卡洛斯·莱穆斯 奈杰尔·琼斯 罗伯特·L·巴宾顿 罗伯特·S·巴宾 于 2017-01-13 设计创作，主要内容包括：提供了一种用于将雾化燃烧器从ON状态转换到OFF状态的方法。燃烧器具有独立可控的雾化空气流、燃烧空气流和燃料流,处于ON状态的燃烧器具有包括雾化空气流、燃烧空气流和燃料流的燃烧器参数的流量值。该方法包括：响应于OFF指令,将雾化空气流、燃烧空气流和/或燃料流中的至少一个改变为较低的非零值；在自改变起的第一段时间后,使燃料流和雾化空气流第一次停止；自第一段时间起在第二段时间内保持燃烧空气流；保持后,使燃烧空气流第二次停止；其中,该保持在转换到OFF状态期间防止在燃烧器内积聚过量热量。(A method for transitioning an atomizing burner from an ON state to an OFF state is provided. The burner has independently controllable atomizing air flow, combustion air flow and fuel flow, and the burner in the ON state has flow values of burner parameters including atomizing air flow, combustion air flow and fuel flow. The method comprises the following steps: changing at least one of the atomizing air flow, the combustion air flow, and/or the fuel flow to a lower non-zero value in response to the OFF command; after a first period of time since the change, stopping the flow of fuel and atomizing air for a first time; maintaining a combustion air flow for a second period of time from a first period of time; after holding, stopping the combustion air flow for a second time; wherein the maintaining prevents excessive heat buildup within the combustor during the transition to the OFF state.)

1. A method for transitioning a burner from an OFF state to an ON state, the burner having independently controllable atomizing air flow, combustion air flow, and fuel flow, the burner in the ON state having flow values for burner parameters including atomizing air flow, combustion air flow, and fuel flow, the method comprising:

a first setting of the combustion air flow to remove excess heat in the combustor;

second setting fuel flow to prime the burner;

changing the combustion air flow and the fuel flow to values that support induced ignition;

igniting the fuel stream;

detecting a flame in a flame tube of a burner; and

in response to the detection, the atomizing air flow, the combustion air flow, and/or the fuel flow is varied to support a target heat output of the combustor.

2. The method of claim 1, wherein the first setting sets the combustion air flow to a maximum output of the combustor over a period of time.

3. The method of claim 2, wherein the second setting occurs after a period of time from the first setting.

4. The method of claim 1, wherein the second setting occurs after a predetermined period of time from the start of the first setting.

5. The method of claim 1, wherein said igniting comprises:

third setting the atomizing air flow to a value that supports induced ignition; and turning on the igniter.

6. The method of claim 1, wherein said varying comprises varying the atomizing air flow, the combustion air flow, and the fuel flow to a value that supports a target heat output of the combustor in response to said detecting.

7. An atomizing burner having an atomizing head and a flame tube, said atomizing burner comprising:

a DC fuel motor adapted to deliver a flow of fuel to the atomizing head;

a DC atomizing air motor adapted to provide an atomizing air flow to an opening in the atomizing head where atomizing air atomizes a fuel flow;

a DC combustion air motor adapted to deliver a flow of combustion air to the flame tube to assist combustion of the atomized fuel;

a controller comprising a combination of hardware and software, the controller programmed to turn the burner ON and OFF, wherein to turn the burner ON, the controller causes the burner to perform operations comprising:

a first setting of the combustion air flow to remove excess heat in the combustor;

second setting fuel flow to prime the burner;

changing the combustion air flow and the fuel flow to values that support induced ignition;

igniting the fuel stream;

detecting a flame in a flame tube of a burner; and

in response to the detection, the atomizing air flow, the combustion air flow, and/or the fuel flow is varied to support a target heat output of the combustor.

8. The burner of claim 7, wherein the first setting sets the combustion air flow to a maximum output of the DC combustion air motor over a period of time.

9. The burner of claim 8, wherein the second setting occurs after a period of time from the first setting.

10. The burner of claim 7, wherein the second setting occurs after a predetermined period of time from the start of the first setting.

11. The burner of claim 7, wherein said igniting comprises:

third setting the atomizing air flow to a value that supports induced ignition; and turning on the igniter.

12. The burner of claim 7, wherein the changing includes changing the atomizing air flow, the combustion air flow, and the fuel flow to a value that supports a target heat output of the burner in response to the detecting.

Technical Field

Various embodiments described herein relate generally to control of operating characteristics of a combustor. More specifically, various embodiments described herein relate to an adjustable atomizing burner that can vary the heat output of the burner by dynamically adjusting the fuel flow, combustion air flow, and atomizing air flow during continuous operation.

Background

Fuel burners are known which are manufactured according to the Babington atomization principle. The method simulates the atomization of water on whale blowholes during the expiration of whales. In the burner, a thin layer of fuel is poured onto a convex surface having minute air holes. Pressurized clean air is forced through the holes and the spray produced upon combustion is very fine, producing no smoke, odor or carbon monoxide. By way of non-limiting example, the air burner series of the BABINGTON TECHNOLOGY burner operates on this principle. Non-limiting examples of patents disclosing BURNERS made according to this principle include, FOR example, U.S. patent 4,298,338 entitled "LIQUID FUEL BURNERS", U.S. patent 4,507,076 entitled "atomic combustion APPARATUS AND METHOD FOR LIQUID FUEL BURNERS AND LIQUID FUELs", or U.S. patent 8,622,737 entitled "solid flame FOR a LIQUID FUEL BURNER", the entire contents of which are incorporated herein by reference.

Referring to fig. 11, an exploded view of an AIRTRONIC burner 1100 is shown. The combustor includes a dual shaft AC motor 1102 having a fixed speed. The AC motor 1102 drives a fuel pump 1104, an atomizing air compressor 1106, and a combustion air blower 1108 together. The fuel pump 1104 delivers a flow of fuel from the reservoir 1110 to a point above a convex head (not shown) of the atomization chamber 1111. The air compressor 1106 injects air through the orifices in the head that inject the fuel as it flows through the orifices of the head and injects the atomized fuel into the flame tubes 1116 (this process is referred to as "atomization" and thus the air compressor 1106 is an "atomizing" air compressor). An igniter (not shown) ignites the atomized fuel. The combustion air blower 1108 delivers an air stream to the flame tubes 1116, combusts the fuel to provide a flame and heat, and carries the heat and burning fuel out of the flame tubes 1116.

In an atomizing combustor, the compressed air stream, the combustion air stream, and the fuel stream must be maintained in a mixing relationship for proper combustion of the fuel. For example, a particular atomizing air stream can only function over a range of fuel flows. Fuel flows beyond this range are too concentrated to be properly atomized, while fuel flows below this range are too dilute to be properly combusted due to too small particles. Fuel flows above or below this range will not burn and/or will burn poorly and may produce byproducts (e.g., smoke, odors).

AIRTRONIC limits flexibility with respect to this relationship by the nature of its design. The fixed speed of the single AC motor 1102 drives the fuel pump 1104, the combustion air blower 1108, and the atomizing air compressor 1106 at respective fixed maximum speeds. The air flow from the compressor 1106 to the atomizer head (not shown) is not adjustable, which limits the potential range of fuel flow rates as described above. The fuel flow rate from the fuel pump 1104 has some flexibility to reduce the fuel flow through an adjustable mechanical restrictor in the fuel flow passage, but this is only achievable at manufacture and cannot be adjusted by the consumer (cannot be disassembled). The combustion air flow is more flexible and can be manually adjusted by knob 1109 to physically restrict the air passage from combustion air blower 1108 to flame tube 116. Although the theoretical range limit is about 0.4-0.6GPH, the design burns fuel at a rate of 0.45-0.55 gallons per hour ("GPH").

In recent years, portable cooking and heating appliances for cooking a considerable number of people in places where kitchen facilities are not available have appeared on the market. For example, disaster relief activities require movable kitchen utensils to be brought to disaster areas and disaster relief centers. Military units require kitchen utensils to support operations while deploying and relocating personnel on a large camp. Restaurants and food providers may wish to cook in remote locations such as beaches, forest areas, street marts, etc. Accordingly, there is a need for portable and/or mobile kitchen appliances.

A difficulty with portable and/or mobile kitchen appliances is that in such cases it is difficult to obtain different types of fuel and to operate under reliable and sufficient power. For example, if a transportation vehicle is running on gasoline and a cooking appliance is running on propane, it is necessary to store, transport and maintain a supply of two different fuels. Gasoline and propane are also volatile fuels that are dangerous to transport and store in the field. Accordingly, organizations that provide such services prefer that the kitchen appliance and the vehicle transporting the kitchen appliance consume the same type of fuel. Liquid distillate fuels, such as AIRTRONIC-combusted diesel fuel, are preferred. Applicants have several patents and applications for utilizing a BURNER (e.g., AIRTRONIC) associated with a portable cooking appliance, such as U.S. patent No. 8,499,755 entitled MOBILE KITCHEN, U.S. patent No. 7,798,138 entitled condensation OVEN directed heated BY a FUEL BURNER, the entire contents of which are incorporated herein BY reference.

The use of AIRTRONIC with portable cooking and/or heating appliances has various drawbacks.

One disadvantage is that AIRTRONIC generates more heat than is required for a particular cooking device, even at its minimum fuel flow rate. Some cooking appliances require over-manufacturing to withstand such heat output, which makes the appliance expensive, heavy and energy inefficient to manufacture. By way of non-limiting example, the oven weight shown in U.S. patent No. 7,798,138, which is capable of withstanding the heat output of an AIRTRONIC, is approximately 800lbs., which limits its portability options.

The temperature of the appliance is also difficult to change. The over-manufactured nature of the appliance, which is required to withstand excessive heat output, produces a correspondingly large specific heat, which makes the appliance slow to heat (wasting time and fuel) and slow to cool (potentially overcooking food). As a non-limiting example, a cook may want to immediately lower the stockpot cooker from a HIGH setting (e.g., boiling) to a LOW setting (e.g., slow stew), but even turning off the burner, this takes several minutes because the HIGH specific heat of the stockpot cooker itself retains the original HIGH heat of the HIGH setting and can only cool slowly.

The temperature of the appliance is also difficult to control. Air tronic controls heat output by a "bang-bang" method in which air tronic is turned ON or OFF as appropriate to reach/maintain a desired temperature, also referred to as a duty cycle. However, it takes 20-30 seconds for the AIRTRONIC to transition ON, and 90-120 seconds to transition OFF. By way of non-limiting example, in an oven that is preheated to 400 degrees, the burner will continue to output heat even when the burner is switched OFF when the oven reaches 400 degrees. Thus, the oven reaches a higher temperature beyond its preheating target, and the specific heat of the appliance will slow the transition from the higher temperature to the desired preheating temperature.

The operation of the AIRTRONIC also consumes significant power because the components are at maximum flow rate when operating. As mentioned above, any adjustment to the flow rate is due to a physical obstruction of the flow-through passage by a flow restrictor which allows flow to be reduced without reducing power consumption. Such power consumption levels are undesirable in view of the limited power availability in the environment in which the portable cooking appliance is utilized.

Drawings

Various embodiments of the present application will be described with reference to the accompanying drawings, in which:

fig. 1 shows an embodiment of the present invention.

FIG. 2 shows the interior of a combustor according to an embodiment of the present invention.

Fig. 3 is an exploded view of the embodiment of fig. 2.

Fig. 4 shows the atomization chamber and flame tube of fig. 2.

Fig. 5 shows the support and the photodiode of fig. 2.

Fig. 6 shows the microcomputer of fig. 2.

Fig. 7 shows the ignition transformer of fig. 2.

Fig. 8 shows the compressor of fig. 2.

Fig. 9 shows the fuel metering pump of fig. 2.

Fig. 10 shows the blower of fig. 2.

Fig. 11 shows a prior art blower.

FIG. 12 is a flow chart of an embodiment of an OFF scheme.

Fig. 13 is a flowchart of an embodiment of the ON scheme.

Detailed Description

In the following description, various embodiments are illustrated by way of example, and not by way of limitation, in the figures of the accompanying drawings. Various embodiments in the present disclosure do not necessarily refer to the same embodiment, and such references mean at least one. While specific implementations and other details are discussed, it should be understood that this is done for illustrative purposes only. A person skilled in the relevant art will recognize that other components and configurations may be used without parting from the scope and spirit of the claimed subject matter.

Several definitions that apply throughout this disclosure will now be presented. The term "substantially" is defined as substantially conforming to a particular size, shape or other characteristic modified by the term such that the component is not necessarily precise. For example, "substantially cylindrical" means that the object resembles a cylinder, but there may be one or more deviations from a true cylinder. The term "comprising" when used means "including, but not necessarily limited to"; the term specifically denotes an open inclusion or membership in a described group, series or the like. The terms "a" and "an" mean "one or more" unless the context clearly dictates otherwise. The term "about" when used in conjunction with a numerical value means a variation that is consistent with the error range of the equipment used to measure the value, which variation can be expected to be ± 5%. "first," "second," and the like are labels used to distinguish between other similarly named components or steps, but do not imply any order or numerical limitation.

As used herein, the terms "front," "back," "left," "right," "top" and "bottom" or other terms of direction, orientation and/or relative position are used for explanation and to facilitate directing certain features of the present disclosure. However, these terms are not absolute and should not be construed to limit the present disclosure.

The shapes described herein are not to be considered absolute. As is known in the burner art, the surface typically has corrugations, protrusions, holes, recesses, etc. to provide rigidity, strength and functionality. All shape (e.g., cylindrical) recitations herein are considered to be modified by "substantially" whether or not explicitly stated in the disclosure or claims, and as noted above are specifically intended in the art to illustrate variations.

Referring now to FIG. 1, a conceptual diagram of a combustor 100 according to an embodiment of the invention is shown. The various components are connected by various passageways that can communicate air and/or liquid such that all of the passageways are considered fluid passageways. It should be understood that, for purposes of the conceptual nature of FIG. 1, each "passage" generally refers to the path of fluid moving from one point of the combustor 100 to another, and does not imply any structure or location of a passage; the passageway may not be a structure at all because it may simply refer to the path that the fluid travels under the influence of gravity.

An atomizing air pump 102 (e.g., an air compressor) is provided to deliver clean air along a passageway 104 to an atomizing chamber supporting at least one atomizing head 106. The atomizing head 106 has a convex face with an orifice for spray dispensing of fuel according to the Babington atomization principle. When fuel is poured onto the atomizing head 106 (as described below) and ignited, the burning fuel will produce a flame plume 108 laterally within the flame tube (not shown in FIG. 1). The atomizing air pump 102 includes a first adjustable speed DC motor 110, the motor 110 being controlled by a microcomputer 112. Thus, the microcomputer 112 controls the flow rate of the atomizing air supplied by the atomizing air pump 102.

The fuel tank 114 is supplied with fuel 116 for the burner 100 and is preferably positioned such that a top surface of the fuel 116 is below the atomizing head 106. An inlet passage 118 extends from the fuel tank 114 to a fuel pump 120, and an outlet passage 122 extends from the fuel pump 120 to a point above the atomizing head 106. The fuel pump 120 includes a second adjustable speed DC motor 124, the DC motor 124 being controlled by the microcomputer 112. Accordingly, the microcomputer 112 controls the flow rate of the fuel stream 126 delivered from the fuel tank 114 to the atomizing head 106.

As is known in the art, the amount of fuel 126 delivered to the atomizing head 106 may exceed the amount that the burner 100 actually ignites. The excess fuel 128 falls by gravity along a return path 130, which return path 130 directs the excess fuel 128 back into the fuel tank 114.

A blower 132 is provided to deliver clean air for combustion along a passageway 134 to an area in front of and around the atomizing head 106, preferably through the interior of a flame tube (not shown). The blower 132 includes a third adjustable speed DC motor 136, the third adjustable speed DC motor 136 being controlled by the microcomputer 112. Thus, microcomputer 112 controls the rate of combustion air to supply flame plume 108.

The conceptual design of fig. 1 may be implemented using various known configurations of components. The various fluid pathways may be made up of hoses, pipes, or portions thereof connected together in a known manner. In the alternative, the various passageways may be drilled through a solid material (e.g., a steel block). In yet another alternative, various passages may be defined in part in opposing blocks that form the passages when the blocks are connected together. Combinations of the above and other connection formation techniques may be used.

Referring now to fig. 2 and 3, there is shown a non-limiting example of an embodiment of a combustor 200 consistent with the concepts of fig. 1. The combustor 200 includes a tube assembly 202, a blower 204, a microcomputer 206, a fuel reservoir 208, an ignition transformer 210, an atomizing air compressor 212, and a fuel metering pump 214. Various components are supported by the housing 216. The components are connected and mounted in a manner known in the burner art and will not be discussed further herein.

Referring now to fig. 3 and 4, the combustion chamber 408 components of the combustor 200 are described in greater detail. Tube assembly 202 includes an outer air tube 402, an inner flame tube 404, and an end cap 405. The blower 204 blows combustion air into the gap between the inner flame tube 404 and the outer air tube 402. Various air louvers 407 are provided in the inner flame tube 404 to inject air to create a swirling combustion process within the inner flame tube 404. Perforated air passages (not shown) may be provided on the end cover 405 to allow combustion air to pass through to cool the flame tube assembly 202 and/or shape the positively-fueled fuel as it emerges from the air-tube flame tube assembly. Non-limiting examples of combustion air mechanisms and air vent/louver arrangements are found in U.S. patent 8,622,737 entitled "fired FLAME vane FOR a LIQUID FUEL BURNER," which is incorporated by reference in its entirety. However, the invention is not so limited and any number of holes or hole displacements may be used to introduce air into the inner flame tube 404.

The atomization chamber 408 is located behind the flame tube 404 and receives fuel from the fuel reservoir 208 (passages not shown). A mounting ring 412 is mounted to the rear of the atomizing chamber 408. The support 410 is mounted behind the ring 412 and supports the photodiode 504 (fig. 5). The nebulizing chamber 408 includes an aperture 414 approximately in the center thereof, and light from within the inner flame tube 404 can pass through the aperture 414 to the photodiode 504. As is known in the art, the atomizing head (e.g., head 106 in fig. 1) is located rearward of the transverse bore 418. The front housing 406 (which is part of the blower 204) has a flange that engages the rear of the outer air tube 402. However, the invention is not so limited and other forms of nebulizing chamber may be used.

Referring now to fig. 5, the support 410 is shown in more detail. The support 410 supports a circuit board 502, which circuit board 502 in turn supports a photodiode 504. The photodiode 504 is part of a flame detection device described in more detail in U.S. provisional patent application 62/274879, discussed above. However, the invention is not so limited and other forms and/or locations of flame detection may be used.

Referring now to FIG. 6, the microcomputer 206 is shown in greater detail. From a hardware perspective, the microcomputer 206 includes a cover part 602, a circuit board part 604, and a display 606. The circuit board components include standard computer components such as at least one interface, display, processor, memory, wireless modem, jack for wired modem, etc., as is well known in the art and will not be discussed further herein. Microcomputer 206 also includes software and/or stored data to control the operation of burner 200, as discussed further herein. The software may be updated periodically to allow for new control schemes. The invention is not limited to the details of implementation of microcomputer 206 and the functions therein may be one unit as shown, multiple units, and/or in cooperation with an external computer.

Referring now to fig. 7, ignition transformer 210 is shown in greater detail. Ignition transformer 210 includes a housing component 702 and a printed circuit board 704. Ignition transformer 210 converts available external power (AC or DC, not shown) to power to generate a spark that is provided to electrodes (not shown) in the atomization chamber 408, as is known in the burner art. However, the invention is not so limited and other forms of igniters may be used.

Referring now to FIG. 8, the atomizing air pump 212 is shown in greater detail. The atomizing air pump 212 includes a DC motor 802 below the frame 804, bearings 806, a piston 808, a piston bushing 810, a balance 812, an O-ring 814, a piston ring 816, and a compressor cylinder head 818. However, the invention is not so limited and other forms of atomizing air pumps may be used. The DC motor 802 drives the piston 808 to provide clean air to the orifices in the atomizing head 418 to inject fuel.

Referring now to FIG. 9, the fuel pump 214 is shown in greater detail. The bottom substrate 902, support plate 904, and top plate 906 define an interior chamber 908, the interior chamber 908 having a fluid inlet passageway 910 and an outlet passageway 912. The DC motor 914 drives a gear 916 within the inner chamber 908 to draw fluid from the fuel reservoir 208 to the atomization chamber 408. However, the invention is not limited thereto, and other forms of fuel pump may be used.

Referring now to FIG. 10, the blower 204 is shown in greater detail. The housing is defined by a front housing 406, an intermediate support 1002, and a rear housing 1004. As described above, the DC motor 1006 drives the blower wheel 1008 to draw air through the opening in the rear housing 1004 and blow it out of the front housing 406 into the space between the inner tube 402 and the outer tube 404. The intermediate support provides mounting points for the motor 1006 and blower wheel 1008.

The above-described embodiment burns the fuel in a manner consistent with the Babington atomization principle. The fuel pump 214 delivers fuel over the atomizing head 416. The atomizing air pump 212 pumps air through holes in the atomizing head, injecting the delivered fuel into the inner flame tube 404. The blower 204 delivers combustion air into the inner flame tube 404 to facilitate fuel combustion. Ignition transformer 210 ignites the fuel spray to initiate combustion.

The microcomputer 206 is connected to three DC flow motors 802,914 and 1006. As a DC motor, the speed is adjustable to adjust the flow rates of the fuel, atomizing air and combustion air. Thus, the microcomputer 206 can control the speed of the three flow parameters that define how much heat the burner 200 generates, for example by controlling the amount of applied voltage or the pulse rate of the motor. The present invention is not limited by the manner in which the microcomputer 206 controls the speed of the DC motor.

As discussed above, in an atomizing combustor, the compressed air flow, the combustion air flow, and the fuel flow must be maintained in a relationship to properly combust the fuel. Accordingly, microcomputer 112 is programmed based on the protocol to set these three flow parameters to meet the desired target of the system, which may be a target operating temperature of the appliance (e.g., 350 degrees) or a certain heat output (e.g., low, medium, high and gradations therebetween). Preferably, this is done by an algorithm and/or by a parameter database to meet the specific requirements of the environment (e.g. type of appliance, type of fuel, outside temperature, presence of rain, etc.). For example, the amount of heat required to heat a stockpot cooker is different from the amount of heat required to heat an oven, which is larger and traditionally operates at higher temperatures. Thus, the microcomputer can retain one set of operating schemes for ovens, another set of operating schemes for soup pot cookers, and so on.

The scheme may be specific, for example, for achieving a desired heat output with all three flow parameters set to specific values. The approach may be adaptive in that the approach is based on a current state of the combustor relative to a target state; for example, the flow parameters for heating the oven from a room temperature starting state to 400 degrees may be different than if the starting state (or current state) of the oven had been at 300 degrees. The scheme may operate according to a "bang-bang" approach, or may adjust the flow rate to "soft landing" at the target output in response to current or predicted conditions to minimize overshoot. This scheme may require certain flow parameters to use a higher heat output in cold or rainy conditions or to reduce heat output in hotter conditions. Other schemes may also be used. A scheme based on a combination of factors may also be used. Embodiments are not limited by the nature of the protocol used.

The microcomputer 206 may be programmed to implement a specific transition ON scheme and transition OFF scheme for the burner 200.

With respect to the ON scheme, the parameters of the atomizing air flow, the combustion air flow, and the fuel flow for igniting the fuel may be different as compared to operating the blower. Thus, the ON scheme implemented by the microcomputer 112 may set the flow parameters to a combination specifically for ignition, detect the presence of a flame by the flame detector, and then set the flow parameters to a combination specifically for operating the burner 200. Some or all of the parameters used for ignition may be the same or different with respect to operation.

A non-limiting example of an ON schedule for the combustor 100 of FIG. 1, implemented by the microcomputer 112 to regulate the speed of the motors 110, 124 and 136, is shown in FIG. 12. Starting from an OFF state where all motors are inactive, an ON command is received at step 1202. At step 1204, the blower removes any excess heat from the combustor 100, preferably by setting the motor 136 to its maximum speed (e.g., 6500rpm) for a period of time (e.g., 30 seconds) or until the combustor ambient temperature drops below a certain value. After completing step 1204, then, at step 1206, the fuel pump 120 primes fuel to the atomizing head 106, preferably starting with the electric motor 124 at a low speed (e.g., 600rpm) and gradually increasing to a priming speed of fuel (e.g., 1200rpm) over a period of time (e.g., 15 seconds); the objective is to drive all of the air out of the fuel line and to fully wet the atomizing head 106. At step 1208, the speed of the blower and fuel pump outputs is reduced to cause ignition (e.g., motor 124 is reduced to 400rpm and motor 136 is reduced to 3500 rpm). After the combustor reaches the new speed, the fuel is ignited by turning on the igniter and setting the electric motor 112 of the atomizing air compressor 102 to an ignition speed (e.g., 2200rpm) at step 1210. At step 1212, the presence of a flame is detected in the flame tube (e.g., by the method of US 62/274879, although the invention is not limited thereto). In response to the confirmation of the flame, the igniter is turned off 1214, and various flow parameters of the combustor 100 are changed to output a desired amount of heat.

For a non-limiting embodiment of the OFF schedule, the flow parameters are made continuous (i.e., not set to zero), but at least one flow parameter is changed to preferably reduce heat output, produce minimal contamination during the shut down schedule, and apply minimal pressure to the system. The change may increase or decrease different flow parameters as needed to transition to the closed transition state. After the transient state is reached, the parameters are maintained for a first period of time to allow at least the transient state to stabilize. At the end of the first period, the flow of atomizing air and fuel will stop (e.g., by simultaneous or sequential electrical braking of the electric motor), while the flow of combustion air may continue at different levels; the combustion air flow is no longer used for combustion purposes, but rather prevents heat from accumulating in the combustor 200. After the second period of time, the flow of combustion air is stopped (e.g., by electrical disconnection of the motor). The first and second times may be predetermined or based on reaching a detected target condition. Additionally and/or alternatively, the approach may include reversing the fuel flow (e.g., by a reversing operation of the motor 914) to clean the fuel line.

A non-limiting embodiment of an OFF scheme with respect to the burner 100 of fig. 1 is shown in fig. 13, which is implemented by the microcomputer 112 to adjust the speed of the motors 110, 124 and 136. Starting from an ON state where all motors are active, an OFF command is received at step 1302. At step 1304, the speed of the motors 110, 124, and 136 is changed to a predetermined non-zero transition level (e.g., 1200rpm for the atomizing air pump 102, 300rpm for the fuel pump 120, 3000rpm for the blower 132) and held for a period of time (e.g., 1-3 seconds) to stabilize the combustor 100. At step 1306, the atomizing air pump 102 and fuel pump 120 are reduced in speed (e.g., stopping power flow or electric braking, such reduction preferably being 0rpm to stop flow completely); preferably, at the same time, but may be reduced sequentially. At step 1308, the blower continues to operate to remove excess heat, preferably by increasing the motor 136 to a maximum value (e.g., 6500rpm) and maintaining the air flow for a period of time (e.g., 2 minutes) or until the burner or burner-heated appliance drops to a desired temperature of 150F. When the target time/temperature is reached, at step 1310, the blower 132 is turned off; the air pump 102 and fuel pump 120 are turned off at this time if not previously turned off.

The above-described embodiments overcome various disadvantages of prior art AIRTRONIC burners, particularly those associated with portable cooking appliances.

For example, the minimum fuel flow rate for combustor 200 is approximately 0.155GPH, which is approximately 40% of the AIRTRONIC heat output and fuel consumed. Thus, embodiments herein may generate less heat and consume less fuel than AIRTRONIC. This embodiment also consumes less power because, unlike the AIRTRONIC, the motor 802/914/1006 need not operate at maximum output. The current variable burn rate range is 0.155GPH to 1.0GPH, far exceeding the operating range of prior art AIRTRONIC burners.

Because embodiments herein may generate less heat than air tronics, the embodiments may be used with lighter/smaller cooking appliances and/or enable off-grid self-powering capabilities. As a non-limiting example, as mentioned above, ovens used with AIRTRONIC are over-manufactured to withstand heat output and weigh approximately 800lbs., and have a correspondingly high specific heat, making the oven slow to heat or cool. Embodiments herein may be used with an oven of about 200-.

Embodiments herein may also operate without relying on the "bang-bang" approach, but rather reduce the fuel flow rate as the target temperature is approached. This reduces the possibility of overshooting the target temperature. Embodiments may enable precise load matching of the heat output of the burner to the load requirements of the appliance.

Embodiments herein also eliminate any need for a second blower in the appliance to prevent heat build-up. As described above, when the AIRTRONIC is turned OFF, heat must be prevented from accumulating within the flame tube; since the primary blower is not operating, there is typically a secondary blower to provide 90-120 seconds of ventilation. In embodiments of the present application, the blower 132 may continue to operate during this period to provide ventilation. Accordingly, embodiments herein eliminate any need for a second blower (although such a second blower may still be present).

Embodiments of the present application relate to the use of a burner with a cooking appliance. However, the invention is not so limited and may be used in other environments.

The specification and drawings are, accordingly, to be regarded in an illustrative rather than a restrictive sense. It will, however, be evident that various modifications and changes may be made thereto without departing from the broader spirit and scope of the invention as set forth in the claims that follow.