DOMESTIC GAS APPLIANCE WITH FLAME CONTROL

Abstract

A domestic gas appliance is disclosed. In one implementation the appliance includes a burner and a gas control valve situated to deliver and vary a flow of a gas to the burner. The gas control valve has an actuator that induces an opening and/or closing of the flow control valve dependent on a control signal delivered to the actuator. A control device is electrically coupled to the actuator and is used to control the opening and closing of the gas control valve. The control device is coupled to an audio input and is configured to receive an analog sound signal and to generate the control signal based on the analog sound signal. A method of modulating a flame in a burner of a domestic gas appliance is also disclosed. In one implementation the method includes producing an analog sound signal and subsequently creating a reference signal based on the analog sound signal. A control signal is produced using the reference signal with the relationship between the reference signal and the control signal being linear, logarithmic or potential. The control signal is delivered to an actuator of a gas control valve that is situated to control the flow of gas to the burner, the control signal acting upon the actuator to cause the actuator to open and/or close to modulate the flame in the burner.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is related to and claims priority to Spanish Patent Application No. P200930261, filed Jun. 4, 2009.

TECHNICAL FIELD

This invention relates to domestic gas appliances and, more specifically, to domestic gas appliances in which a flame is generated and in which the flame can be modified by acting on at least one valve.

BACKGROUND

Up until very recently domestic heating appliances and even lighting appliances functioned by burning solid materials such as wood. However, these types of appliances are gradually being replaced by appliances that burn non-solid materials such as gas or which generate heat or light electrically. The latter types of appliances do not, therefore, produce the combustion effect of flames that appliances burning solid materials do (e.g., visual effect and/or sound effect). The combustion effect often causes the user to feel a sense of well-being and relaxation that they do not experience with gas or electrical appliances.

In order to solve the absence of the combustion effect and generate these sensations in the user, different types of appliances are now appearing on the market. One type is electrical appliances that simulate the flame or fire to obtain these combustion effects, some of them even simulating the sound produced by the flames. An example of this type of appliance is disclosed in the document US20070125367A1 where a flame is simulated by electronic means. At least one light source, such as LEDs, is used to achieve this in conjunction with a microprocessor that is used to vary the intensity of the light and its colour of the light (of the LEDs) in order to simulate the natural effect of a live flame. Simulation of logs and wood are also disclosed.

Appliances that heat and/or light by means of a non-solid fuel such as gas for example, hereinafter referred to as gas appliances, comprise at least one burner to which the gas is supplied, a flame being generated in the burner when the gas is ignited. The intensity of the flame depends on the gas (or on an air-gas mixture) that reaches the burner, and there are known appliances that, in order to simulate the effect of combustion cause a modification of the flame by the blowing an air current directly into the burner (or onto the flame generated in the burner) for example, thereby altering the flame, which modifies its shape in accordance with the air current directed into the burner. U.S. Pat. No. 6,162,045 discloses an example of this type of appliances, in which the vibrations of a speaker disposed in the burner disturb the air-gas mixture that reaches the burner, the flame being altered in accordance with the vibrations.

In other gas appliances, in order to simulate a combustion effect, the gas that reaches the burner is regulated by acting on a valve that regulates the passage of the gas to the burner. Normally, the valve is acted on in accordance with preset patterns, the user being able to select among a preset number of patterns at any given moment. These patterns can imitate known music or even certain ambiences such as a romantic ambience. U.S. Publication No. 2005/0208443A1 discloses a gas heating appliance that comprises control means for regulating the characteristics of a gas generated flame, such as its frequency and size, thereby providing a combustion effect. To achieve this, the control means acts on a valve to regulate the gas that reaches the burner. The control means comprises a plurality of preset control modes or patterns that can be selected to control the valve according to the pattern selected by the user. However, a user of such appliance is unable to recreate ambiences that have not been preset in the control means.

SUMMARY OF THE DISCLOSURE

It is an object of the present invention to provide a domestic gas appliance in which a flame can be modified to provide an aesthetic visual effect.

In one implementation, a domestic gas appliance is provided that comprises at least one burner where a flame is generated, at least one valve associated to the burner and which regulates the passage of gas to the burner, and control means that is associated to the valve and which is adapted to generate a control signal for controlling the position of the valve based on an analog audio/sound input for the purpose of regulating the flow of gas to the burner.

In one implementation the control means receives a reference signal representative of the amplitude of the analog sound signal and generates the control signal in accordance with the reference signal. The different values (amplitudes) of the analog sound signal are not stored or selected beforehand. As such, the control means generates a control signal in accordance with a reference signal representative of sounds generated in real-time. As a result, the user can select in real-time a sequence of sounds in order to produce a flame to recreate a desired ambience or feeling at any given moment without being forced to select from among a limited number of preset ambience. At the same time the domestic gas appliance fulfils its main function, which can be heating (if it is a gas stove/heater) or lighting (if it is a gas lamp) for example.

In accordance with one implementation, a domestic gas appliance is provided comprising a burner; a gas control valve, when coupled to a gas source, situated to deliver a flow of the gas to the burner, the gas control valve having an actuator that induces an opening and/or closing of the flow control valve; and a control device electrically coupled to the actuator to control the opening and closing of the gas control valve, the control device coupled to an audio input and configured to receive an analog sound signal and to generate a control signal based on the analog sound signal deliverable to the actuator to cause the actuator to induce a modulation of a flame in the burner.

In accordance with another implementation, a kit for incorporation into a domestic gas appliance having a burner is provided, the kit comprising a gas control valve connectable between a gas source and the burner, the gas control valve having an actuator that induces an opening and/or closing of the gas control valve; and a control device electrically coupled to the actuator to control the opening and closing of the gas control valve, the control device coupled to an audio input and configured to receive an analog sound signal and to generate a control signal based on the analog sound signal deliverable to the actuator to cause the actuator to open and/or close for the purpose of inducing a modulation of a flame in the burner.

In accordance with another implementation, a method of modulating a flame in a burner of a domestic gas appliance is provided, the method comprising producing an analog sound signal, creating a reference signal based on the analog sound signal, acting on the reference signal to create a control signal, the reference signal being acted upon to establish either a linear, a logarithmic or a potential relationship between the reference signal and the control signal; and delivering the control signal to an actuator of a gas control valve that is situated to control the flow of gas to the burner, the control signal acting upon the actuator to cause the actuator to open and/or close to modulate the flame in the burner.

These and other advantages and characteristics of the invention will be made evident in the light of the drawings and the detailed description thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 schematically shows a gas appliance in one implementation.

FIG. 2a shows a linear relationship between a reference signal and a control signal of an appliance, such as that illustrated in FIG. 1.

FIG. 2b shows a logarithmic relationship between a reference signal and a control signal of an appliance, such as that illustrated in FIG. 1.

FIG. 2c shows a potential relationship between a reference signal and a control signal of an appliance, such as that illustrated in FIG. 1.

FIG. 3a represents the variations in amplitude of a melody for which the most suitable relationship is a linear relationship and also a reference signal representative of the variations.

FIG. 3b represents the variations in amplitude of a melody for which the most suitable relationship is a logarithmic relationship and also a reference signal representative of the variations.

FIG. 3c represents the variations in volume of a melody for which the most suitable relationship is the potential relationship and also a reference signal representative of the variations.

FIG. 4a illustrates a burner of an appliance in one implementation.

FIG. 4b illustrates a burner of the appliance in another implementation.

FIG. 5 is a cross-sectional view of a valve of an appliance in one implementation, with a voice-coil type actuator.

FIG. 6 is a block diagram illustrating a kit in one implementation for incorporation into a domestic gas appliance.

DETAILED DESCRIPTION

FIG. 1 illustrates, in the form of a block diagram, a domestic gas appliance 100 according to one implementation of the present invention. The appliance 100 may be, for example, a gas heating appliance, a gas stove, or a lighting appliance such as a gas lamp. In one implementation appliance 100 comprises at least one burner 1 where a flame is generated, at least one valve 2 associated to the burner 1, and control means 3 that is associated with valve 2 and which is adapted to generate at least one control signal Sc used in the control of valve 2 to regulate the passage of gas to burner 1. The appliance 100 may also comprise lighting means, such as, for example, an igniter or a spark generator (not shown in the figures) to ignite the flame in the burner 1. In one implementation the control means 3 is adapted to cause the lighting means to ignite the gas that reaches burner 1 at a given moment, the flame being generated as a result of the lighting. The control means 3 may comprise a DSP (Digital Signal Processor), a control device, a microprocessor or an equivalent device.

In one implementation the control means 3 receives an analog reference signal Sref representative of the amplitudes of a sequence of sounds, and generates the control signal Sc in accordance with a reference signal Sref to cause the flame in the burner 1 to move in accordance with the sequence of sounds. In some implementations the control signal Sc is digital, while in other implementations the control signal Sc is analogical.

In one implementation the sequence of sounds comprises a melody or music, although any other type of sequences can be used, such as, for example, the simulation of sea-waves. In one implementation the sequence of sounds is generated by a stereo, music centre or any other type media player 5 that transmits an analog sound signal Sson identifying the music it is playing. In one implementation the appliance 100 comprises an amplifying stage 6 that receives the sound signal Sson and which regulates the gain of the sound signal Sson. In one implementation, if the sound signal Sson has very high voltage values the amplifying stage 6 decreases the voltage values, if the sound signal Sson has very low voltage values it increases the voltage values, and if the sound signal Sson has intermediate or acceptable voltage values it maintains voltage values. Voltage values that can be accepted and treated by the control means 3 can be understood as intermediate or acceptable voltage values, which can depend on the control means 3 used.

In one implementation the appliance 100 comprises an adaptation stage 7 where the signal leaving the amplifying stage 6 is treated. In one implementation the manufacturer presets the parameter of the signal that is to be taken into account in generating the control signal Sc, which can correspond with its size (instantaneous signal), its effective value or which can be in accordance with the detection of peaks, for example. The output signal of the adaptation stage 7 corresponds with the reference signal Sref that reaches the control means 3, as shown in FIG. 1, the control means 3 generating the control signal Sc in accordance with the reference signal Sref. FIGS. 3a and 3c illustrate exemplary reference signals, Sref, producible by an adaptation stage 7.

The relationship between the reference signal Sref and the control signal Sc may be, for example, linear, logarithmic or potential, which are represented by the curves shown in FIGS. 2a, 2b and 2c respectively. FIGS. 3a, 3b and 3c show three different types of melodies, with different rhythms, shown in accordance with the variations in the amplitudes (peaks and/or valleys) of the melodies (reference signal Sref in the x-axis). In the representation shown in FIG. 3a, the amplitude of the melody suffers frequent variations between an area of maximum levels Zmax and an area of minimum levels Zmin, these being major variations in amplitude, as a result of which the most suitable relationship to be applied in this case is the linear relationship shown in FIG. 2a. In the representation shown in 3b, the volume of the melody suffers frequent variations only in the area of minimum levels Zmin, these being minor variations in amplitude, and suffers very few variations between the area of minimum levels Zmin and the area of maximum levels Zmax, and/or area of maximum levels Zmax. In this case, therefore, in order to achieve good resolution, especially in the variations in amplitude of the area of minimum levels Zmin, as a result of which the most suitable relationship to be applied in this case is the logarithmic relationship shown in FIG. 2b, by means of which a small range of analog input values (x-axis) of the area of minimum levels Zmin corresponds to a large range of digital output values (control signal Sc in the y-axis). In the representation shown in FIG. 3c, the amplitude of the melody suffers frequent variations only in the area of maximum levels Zmax, these being minor variations in amplitude, and suffers very few variations between the area of maximum levels Zmax and the area of minimum levels Zmin, and/or in the area of minimum levels Zmin. In this case, therefore, in order to achieve a good resolution, especially in the variations in amplitude of the area of maximum levels Zmax, as a result of which the most suitable relationship to be applied in this case is the potential relationship shown in FIG. 2c, by means of which a small range of analog input values (x-axis) of the area of maximum levels Zmax corresponds to a large range of digital output values (control signal Sc in the y-axis). In one implementation, the control means 3 automatically selects the most appropriate relationship to be applied. In another implementation one or more user interfaces are provided that enables the user to select between an automatic mode and a manual mode. In the automatic mode the control means automatically selects the most appropriate relation, whereas in the manual mode the user is permit to select the relationship to be applied.

Appliance 100 may comprise a single burner 1 with a single combustion area 1a where a flame is ignited, or with a plurality of combustion areas 1a where a flame is capable of being ignited in each of the combustion areas 1a. Appliance 100 may also comprise a plurality of burners 1, each of them comprising one or more combustion areas 1a. In one implementation appliance 100 comprises, for each combustion area la, an associated gas supply valve 2 with the control means 3 capable of generating a control signal Sc for each valves 2. The control signals Sc may be equal or different for all the valves 2. In one implementation control signals Sc having different relationships (e.g., linear, logarithmic, potential) with the reference signal Sref are supplied to different valves 2 of a gas appliance. For example, in one implementation a control signal Sc having a linear relationship with the reference signal Sref is supplied to one valve 2 while a control signal Sc having a logarithmic or potential relationship with the reference signal Sref is supplied to another valve 2. In general, in each combustion area 1a the flame may be modulated or modified separately to the rest of the combustion areas 1a. The burner 1 is not restricted to a specific shape and/or arrangement and can comprise any conventional shape such as those shown in FIG. 4a (with a single combustion area 1a in this case) and in FIG. 4b (with two combustion areas 1a in this case, also disposed at different heights). In each combustion area 1a the corresponding tube 1c comprises a plurality of grooves 1a′ through which the flame exits to the outside. As shown in FIG. 4b, additionally, the shape and/or arrangement of a combustion area 1a (of a pipe 1c where the combustion area 1a is disposed) may be different to that of another combustion area 1a (the pipe 1c of another combustion area 1a), and the burner 1 can comprise an intermediate pipe 1b to connect the flame of one combustion area 1a with another combustion area 1a, so that the flames present in the burner 1 display a continuity despite being generated in different combustion areas 1a.

To obtain a flame that represents the amplitude of the sequence of sounds in the most realistic way possible, the use of valves 2 that can be opened and closed at high speeds, speeds in excess of about 30 Hz for example, is advised. In one implementation of the present invention the valve 2 comprises a voice-coil type actuator as shown in FIG. 5. This type of actuator comprises a permanent magnet 2b, and in one implementation the permanent magnet 2b is axially magnetised while in another it is radially magnetised. Alternatively, the valve 2 may comprise, without limitation, a piezoelectric-bender actuator or an ultrasonic-type motor, which can also be opened and closed at high speeds.

In one implementation valve 2 comprises a voice-coil type actuator. This type of actuator comprises a moving part 2a (moving reel), the movement of which causes the valve 2 to open and close, thereby enabling or preventing the passage of gas to the burner 1. In one implementation the voice-coil has a low mechanical inertia in order to allow the moving part 2a to move at frequencies of 30 Hz or greater. In order to cause the moving part 2a to move, an electrical current is supplied to the actuator with the result that a magnetic field is generated that is opposed to the force exerted by the permanent magnet 2b, causing the valve 2 to open. In one implementation appliance 100 comprises a driver 8 or a control system (not shown in the figures) for the valve 2, which receives the control signal Sc. In such an implementation the driver 8 generates the electrical current for the actuator of the valve 2 in accordance with the control signal Sc, which in the implementation in which the control signal Sc is digital it can be a square wave signal. The square signals may comprise, in each period, an interval Ton in which the signal corresponds with a “1” logic, and an interval Toff in which the signal corresponds with a “0” logic, the relationship between the intervals Ton and Toff being known as a duty-cycle. The adjusting of the duty-cycle of the electrical current signal enables the opening and closing of the valve 2 to be controlled. In the implementation in which the control signal Sc is analogical, the valve 2 can comprise intermediate positions, not only a totally open position or a totally closed position, different amounts of gas being allowed through said valve 2 towards the burner 2 depending on said control signal Sc.

The sequence of sounds is generated by a sound device 5, which in one implementation is a conventional device that is already disposed with an output that corresponds with the sound signal Sson. The sound device 5 can comprise, for example, capture devices such as CD and DVD players, microphones etc, or devices known as virtual electronic devices, such as a guitar or an electronic baton for example. The sound device 5 can also be a device external to the heating appliance 100, as shown in FIG. 1, or it can be built into the appliance 100 itself. In the event that the sound device 5 is external, the appliance 100 comprises an input 15 for receiving the sound signal Sson originating from the sound device 5, which in one implementation comprises a plug.

In one implementation, a control system of the present invention includes an ON/OFF switch that permits a user of the system to deactivate the control system. When the OFF mode is selected, the gas control valve 2 is adapted to remain open in spite of any audio signal introduced into the system. In one implementation the ON/OFF control switch is operatively connected to the control means 3 so that a control signal is generated to maintain the gas control valve 2 open. In another implementation the ON/OFF switch deactivates the control means 3, or otherwise acts upon other control system components in a manner such that no control signal is delivered to the gas control valve 2, the gas control valve being adapted to assume and maintain an open position in the absence of receiving a control signal.

An advantage of present invention is that it may easily be integrated into a wide variety of gas appliances. In one implementation a kit 300 for integration into a convention gas appliance is provided. In one implementation, as shown in FIG. 6, the kit comprises a gas control valve 200 and a controller 205, with an optional ON/OFF switch 20. In the example of FIG. 6, the gas control valve 200 is installed in the gas line 208 between a shut-off valve 210 and a gas burner 220. In one implementation, the shut-off valve 210 is a safety valve that is coupled to a thermocouple situated in or near the burner and is adapted to close upon a disruption or extinguishing of a pilot flame associated with the burner 220. In another implementation the shut-off valve is a manually operated valve. In one implementation the controller 205 comprises at least an analog input for receiving an analog audio signal and also a control device/control means, similar to that previously discussed, for generating a control signal to be delivered to and regulate the position of control valve 205. In addition to the control device, the controller may include one or more of the components 5, 6, 7, 8 and 9 or any of the other features previously described herein.

Although the present invention has been disclosed in the context of certain embodiments and examples, it will be understood by those skilled in the art that the present invention extends beyond the specifically disclosed embodiments to other alternative embodiments and/or uses of the invention and obvious modifications and equivalents thereof. Thus, it is intended that the scope of the present invention herein disclosed should not be limited by the particular disclosed embodiments described above.

Claims

1. A domestic gas appliance comprising:

a burner,

a gas control valve, when coupled to a gas source, situated to deliver a flow of the gas to the burner, the gas control valve having an actuator that induces an opening and/or closing of the flow control valve; and

a control device electrically coupled to the actuator to control the opening and closing of the gas control valve, the control device coupled to an audio input and configured to receive an analog sound signal and to generate a control signal based on the analog sound signal deliverable to the actuator to cause the actuator to induce a modulation of a flame in the burner.

2. The domestic appliance according to claim 1, wherein the control signal is an analog signal.

3. The domestic gas appliance according to claim 1, wherein the control signal is a digital signal.

4. The domestic gas appliance according to claim 1, further comprising an amplifier that is configured to regulate the gain of the analog sound signal prior to the analog sound signal being received in the control device.

5. The domestic gas appliance according to claim 4, further comprising an adaptation stage that is configured to receive the analog sound signal from the amplifier and to generate a reference signal to be delivered to the control device, the reference signal based on the analog sound signal.

6. The domestic gas appliance according to claim 1, further comprising an adaptation stage that is configured to receive the analog sound signal and to generate a reference signal to be delivered to the control device, the reference signal based on the analog sound signal.

7. The domestic gas appliance according to claim 1, further comprising an input adapted for connection to a sound generating device to receive the analog sound signal.

8. The domestic gas appliance according to claim 1, further comprising an integrated sound generating device that is configured to generate the analog sound signal.

9. The domestic gas appliance according to claim 3, further comprising a driver that is configured to receive the control signal and which generates therefrom a square wave current signal deliverable to the actuator, the opening and closing of the gas control valve being regulated in accordance with the duty-cycle of the square wave current signal

10. The domestic gas appliance according to claim 6, wherein the control device is configurable to act upon the reference signal so that the relationship between the reference signal and the control signal is linear.

11. The domestic gas appliance according to claim 6, wherein the control device is configurable to act upon the reference signal so that the relationship between the reference signal and the control signal is logarithmic.

12. The domestic gas appliance according to claim 6, wherein the control device is configurable to act upon the reference signal so that the relationship between the reference signal and the control signal is potential.

13. The domestic gas appliance according to claim 1, wherein the actuator comprises a voice-coil type actuator that when operated operates at frequencies of about 30 Hz or greater.

14. The domestic gas appliance according to claim 1, wherein the burner comprises a plurality of combustion areas, the appliance comprising a plurality of gas control valves, one gas control valve for each combustion area.

15. The domestic gas appliance according to claim 14, wherein the control device is adapted to generate a separate control signal, one for each of the plurality of gas control valves.

16. The domestic gas appliance according to claim 6, wherein the control device is configured to automatically act upon the reference signal to establish either a linear, a logarithmic or a potential relationship between the reference signal and the control signal.

17. The domestic gas appliance according to claim 6, further comprising a user interface coupled to the control device and selectable between an automatic mode and a manual mode, in the automatic mode the control device configured to automatically act upon the reference signal to establish either a linear, a logarithmic or a potential relationship between the reference signal and the control signal, in the manual mode the control device configured to act upon the reference signal to establish either a linear, a logarithmic or a potential relationship between the reference signal and the control signal based on a manual selection of a user of the gas appliance.

18. A kit for incorporation into a domestic gas appliance having a burner, the kit comprising:

a gas control valve connectable between a gas source and the burner, the gas control valve having an actuator that induces an opening and/or closing of the gas control valve; and

a control device electrically coupled to the actuator to control the opening and closing of the gas control valve, the control device coupled to an audio input and configured to receive an analog sound signal and to generate a control signal based on the analog sound signal deliverable to the actuator to cause the actuator to open and/or close for the purpose of inducing a modulation of a flame in the burner.

19. The kit according to claim 18, wherein the control signal is an analog signal.

20. The kit according to claim 18, wherein the control signal is a digital signal.

21. The kit according to claim 18, further comprising an amplifier that is configured to regulate the gain of the analog sound signal prior to the analog sound signal being received in the control device.

22. The kit according to claim 21, further comprising an adaptation stage that is configured to receive the analog sound signal from the amplifier and to generate a reference signal to be delivered to the control device, the reference signal based on the analog sound signal.

23. The kit according to claim 18, further comprising an adaptation stage that is configured to receive the analog sound signal and to generate a reference signal to be delivered to the control device, the reference signal based on the analog sound signal.

24. The kit according to claim 18, further comprising an input adapted for connection to a sound generating device to receive the analog sound signal.

25. The kit according to claim 18, further comprising an integrated sound generating device that is configured to generate the analog sound signal.

26. The kit according to claim 20, further comprising a driver that is configured to receive the control signal and which generates therefrom a square wave current signal deliverable to the actuator, the opening and closing of the gas control valve being regulated in accordance with the duty-cycle of the square wave current signal

27. The kit according to claim 23, wherein the control device is configurable to act upon the reference signal so that the relationship between the reference signal and the control signal is linear.

28. The kit according to claim 23, wherein the control device is configurable to act upon the reference signal so that the relationship between the reference signal and the control signal is logarithmic.

29. The kit according to claim 23, wherein the control device is configurable to act upon the reference signal so that the relationship between the reference signal and the control signal is potential.

30. The kit according to claim 18, wherein the actuator comprises a voice-coil type actuator that when operated operates at frequencies of about 30 Hz or greater.

31. The kit according to claim 18, wherein the burner comprises a plurality of combustion areas, the appliance comprising a plurality of gas control valves, one gas control valve for each combustion area.

32. The kit according to claim 31, wherein the control device is adapted to generate a separate control signal, one for each of the plurality of gas control valves.

33. The kit according to claim 23, wherein the control device is configured to automatically act upon the reference signal to establish either a linear, a logarithmic or a potential relationship between the reference signal and the control signal.

34. The kit according to claim 23, further comprising a user interface coupled to the control device and selectable between an automatic mode and a manual mode, in the automatic mode the control device configured to automatically act upon the reference signal to establish either a linear, a logarithmic or a potential relationship between the reference signal and the control signal, in the manual mode the control device configured to act upon the reference signal to establish either a linear, a logarithmic or a potential relationship between the reference signal and the control signal based on a manual selection of a user of the gas appliance.

35. A method of modulating a flame in a burner of a domestic gas appliance, the method comprising:

producing an analog sound signal,

creating a reference signal based on the analog sound signal,

acting on the reference signal to create a control signal, the reference signal being acted upon to establish either a linear, a logarithmic or a potential relationship between the reference signal and the control signal; and

delivering the control signal to an actuator of a gas control valve that is situated to control the flow of gas to the burner, the control signal acting upon the actuator to cause the actuator to open and/or close to modulate the flame in the burner.

36. The method of claim 35, further comprising regulating the gain of the analog sound signal prior to creating the reference signal.