Combustion – Process of combustion or burner operation – Controlling or proportioning feed
Reexamination Certificate
2002-06-20
2004-05-04
Basichas, Alfred (Department: 3743)
Combustion
Process of combustion or burner operation
Controlling or proportioning feed
C431S042000
Reexamination Certificate
active
06729873
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates generally to an ignition system for a pilotless burner. More particularly, the present invention relates to an automatic flame-out detector and reignition system and method of ignition.
2. Background
Automatic pilotless ignition systems are well known in the art. A typical ignition system will provide primary ignition and, while fuel is flowing to the burner, monitor the flame. In the event of a flame-out condition, the ignition system will reactivate the ignition source to reignite the flame. While such devices have been in wide use in home appliances, their use in recreational devices has been limited.
Automatic ignition systems for home appliances have historically employed one of two ignition methods. Spark gap igniters have been the most prevalent. Generally, a spark gap igniter provides a spark gap at a point where, during an ignition operation, there will simultaneously be fuel and air. During an ignition sequence, the igniter receives electrical power from a power source and transforms the voltage to a level sufficient to overcome the dielectric strength of the air between the electrodes of the spark gap, thereby resulting in an electrical arc across the gap. Typically, the electrical energy for the arc is stored in a capacitor to provide a spark of sufficient energy without placing an instantaneous, unrealistic demand on the power source.
The other common ignition method employs the use of a hot surface igniter. Generally, a small heater element, placed in a position where fuel and air will be present during an ignition sequence, is heated to a temperature above the flash point of the burner's fuel. As fuel comes into contact with the hot surface, it is ignited. Advantages of this system include a constant ignition source during the ignition operation, unlike a spark gap igniter wherein the spark is of relatively short duration, and less complex circuitry is required to activate the ignition source. The disadvantage of the hot surface igniter is the relatively large amount of electrical power required to heat the hot surface element. For battery operated devices, the spark gap igniter is more practical since it potentially requires less electrical power and thus will provide a system with longer battery life.
Recreational appliances are small, light weight devices intended for camping, hiking, picnics, or similar activities. In a typical recreational appliance, an automatic ignition system would ideally be battery operated, totally self-contained and relatively impervious to the elements, such as wind and rain. A camp stove is an example of a recreational appliance well suited for an automatic ignition system.
Typically, a camp stove provides one or two burners and a valve associated with each burner for adjusting the flow of fuel. Some stoves provide a manual ignition system which uses a piezo crystal to convert mechanical energy supplied by the operator to electrical energy for producing an electrical spark to ignite the fuel.
Since camp stoves are intended for outdoor use, it is not uncommon for the flame to become extinguished due to wind. In this event, the user must recognize the flame-out condition and manually re-light the burner, either with a match or, if the stove is so equipped, by operating the igniter mechanism.
In prior art automatic ignition systems designed for home appliances, the size and weight of the ignition system have not been of great concern. Thus, prior art ignition systems have been drawn to an ignition system per burner, resulting in unnecessarily replicated circuitry. In addition, since these devices tend to operate from household power, efficiency of the ignition system has likewise not been of great concern. In an ignition system for a camp stove, however, size, weight, and battery life are important factors and therefore replicating circuitry is undesirable.
Another limitation of prior art automatic ignition systems has been nuisance ignition cycles. Flame-out detection, as employed in home appliances, has been susceptible to false flame-out indications, particularly under windy conditions. Nuisance ignition cycles result in unnecessary sparking which produces a periodic ticking sound. The outdoor environment where a camp stove is generally used, subjects the stove to a far greater range of environmental factors than those of an indoor appliance and thus, aggravates the problems associated with nuisance sparking. Nuisance sparking in a camp stove not only results in an annoying ticking sound, it also results in reduced battery life.
Thus, a heretofore unaddressed need exists in the industry to address the aforementioned deficiencies and inadequacies.
SUMMARY OF THE INVENTION
Preferred embodiments of the present invention provide an automatic flame-out detector and reignition system and method for ignition. Briefly described, in architecture, one embodiment of the apparatus can be implemented as follows. An automatic flame-out detector and reignition system for a fuel burning apparatus comprises at least one spark generator. The spark generator comprises a spark gap and a transformer. The transformer has a primary winding and a secondary winding. The spark gap is connected across the secondary winding of the transformer. A switch is in electrical communication with the primary winding such that when the switch is in a first state, electrical current may flow through the primary winding and when the switch is in a second state, electrical current may not flow through the primary winding. The system comprises at least one flame detector having an output indicating the presence of a flame. A programmable circuit having an input for receiving the output of the flame detector and an output for triggering the spark generator is provided.
Preferred embodiments of the present invention can also be viewed as providing methods of igniting a cooking apparatus. In this regard, one embodiment of such a method, among others, can be broadly summarized by the following steps: (a) monitoring a fuel valve position to determine the position of a fuel valve having an open position and a closed position; (b) triggering a spark generator upon determining the position of the fuel valve being disposed in the open position; (c) monitoring a flame detector to determine a flameout condition; and (d) repeating steps (a) through (d).
Other systems, methods, features, and advantages of the present invention will be or become apparent to one with skill in the art upon examination of the following drawings and detailed description. It is intended that all such additional systems, methods, features, and advantages be included within this description, be within the scope of the present invention, and be protected by the accompanying claims.
REFERENCES:
patent: 4025281 (1977-05-01), Lapp
patent: 5881681 (1999-03-01), Stuart
patent: 5927963 (1999-07-01), Wolcott et al.
patent: 6089856 (2000-07-01), Wolcott et al.
Andoe Ron
McCorkle Bruce
Neufield Hank
Basichas Alfred
Kayden James W.
Thomas Kayden Horstemeyer & Risley LLP
W. C. Bradley Company
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