JPH11304145A - Combustor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately detect the state of combustion of a combustor even when the film of an insulating silicon oxide is formed on the surface of a burner or electrode means due to a volatile silicon compound contained in the air for combustion. SOLUTION: A combustor is provided with a burner 1, an electrode means 3, a variable voltage supplying means 16, a current detecting means 5, a potential detecting means, a potential difference detecting means 18, an arithmetic means 19, a threshold selecting means 20, and a combustion control means 6. The variable voltage supplying means 16 applies at least two different constant voltages across the electrode means 3 and burner 1 and the flame impedance is calculated from the then detected current and potential difference between the two voltages. Since the flame impedance is constant even when a silicon oxide film is formed on the surface of the burner 1 or electrode film 3, the state of combustion of the combustor can be discriminated accurately.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the detection of a combustion state of a combustion device for burning fuel.

[0002]

2. Description of the Related Art Conventionally, a combustion apparatus of this kind is disclosed in
What was described in 13432 gazette etc. was common.

As shown in FIG. 9, a burner 1 for burning fuel and a flame 2 formed on the burner 1 are shown in FIG.
, And a constant voltage is applied between the electrode means 3 and the burner 1 by a voltage supply means 4 such as a DC power supply. Then, the current flowing between the electrode means 3 and the burner 1 is detected by the current detection means 5, and the combustion control means 6 compares this current with a preset threshold value to determine whether the combustion is normal or abnormal. Judgment was made, and if abnormal, combustion control such as forcibly stopping combustion was performed.

[0004] Liquid fuel such as kerosene is ejected from a nozzle 8 facing the inside of the vaporizing cylinder 7 and is heated by a heater 9 embedded in the vaporizing cylinder 7 to be vaporized to become a fuel gas. The fuel gas is mixed with the primary air supplied from the primary air through hole 10 to become a premixed gas. The premixed gas passes through the throttle plate 11 disposed between the burner 1 and the vaporizing cylinder 7 and passes through the burner bottom wall. It was introduced into the burner 1 through the through hole 12. Further, the premixed gas is ignited by the ignition rod 15 fixed to the burner base 14 when passing through the flame hole 13 on the peripheral wall of the burner 1, forming the flame 2.

The flame 2 includes an internal flame 2a formed in the flame hole 13 by a combustion reaction between the premixed fuel gas and the primary air;
An outer flame 2b is formed outside the inner flame 2a by a combustion reaction with surrounding secondary air. The inner flame 2a and the outer flame 2b contain many charged particles such as thermoionized ions and electrons. In particular, the density of the charged particles of the inner flame 2a is larger than that of the outer flame 2b.

The electrode means 3 is fixed to the burner base 14, and the tip 3a of the electrode means 3 is disposed in contact with the inner flame 2a having a high density of charged particles to flow a large current. An auxiliary rod 3b made of a material having a different coefficient of thermal expansion from that of the electrode means 3 is provided at the tip 3a.

According to the above configuration, when a constant voltage is applied between the electrode means 3 and the burner 1, a large amount of charged particles are contained in the flame 2, so that the flame means 2 is connected to the electrode means 3 according to the combustion conditions such as the amount of combustion. A constant current flows between the burners 1. If this current has reached a preset threshold, ignition or combustion is determined to be normal, otherwise misfire or combustion is determined to be abnormal, and if it is determined to be abnormal,
Combustion was forcibly stopped to prevent incomplete combustion.

When volatile organic silicone compounds contained in hair sprays and the like are mixed into combustion air, they cause a chemical reaction with oxygen in the combustion flame, and the surface of the burner 1 and the electrode means 3 is coated with silicon oxide. To form Since silicon oxide is insulative, the resistance value between the electrode means 3 and the burner 1 increases, and the current flowing between the electrode means 3 and the burner 1 decreases despite normal combustion.
As the amount of silicon oxide formed increases, the current decreases. When the current reaches a threshold, the combustion control means 6 determines whether the decrease in current is due to silicon oxide or abnormal combustion such as incomplete combustion. Since it could not be determined, combustion was forcibly stopped.

However, by providing the auxiliary rod 3b at the tip 3a of the electrode means 3, even if an insulating silicon oxide film is formed, the thermal expansion coefficients of the electrode means 3 and the auxiliary rod 3b are different from each other. It is stated that cracks and pits occur on the surface of the coating due to temperature change, and the portion becomes a new conductive portion, the current does not decrease, and the combustion state can be detected without being affected by silicon oxide.

[0010]

However, in the conventional combustion apparatus, the auxiliary rod 3 is attached to the tip 3a of the electrode means 3.
By providing b, even if an insulating silicon oxide film is formed on the surface of the electrode means 3, the current does not decrease, but the silicon oxide film is formed not only on the electrode means 3 but also on the surface of the burner 1. Is also formed. Therefore, if a silicon oxide film is formed on the surface of the burner 1, even if the combustion is normal, the current will still decrease.
Combustion was determined to be abnormal, and there was a problem that combustion was erroneously stopped.

[0011]

According to the present invention, there is provided a burner, an electrode means, a variable voltage supply means, a current detection means, a potential detection means, a potential difference detection means, and a calculation means. , A threshold selection means, and a combustion control means.

According to the present invention, the variable voltage supply means can supply a plurality of different constant voltages between the electrode means and the burner. At this time, the flame impedance is calculated from the current detected at each voltage and the potential difference. be able to. Since the flame impedance is constant even when silicon oxide is formed, the combustion state can be accurately determined.

[0013]

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a burner, electrode means disposed in contact with a flame formed on the burner, and variable voltage supply means for supplying a voltage between the electrode means and the burner. Current detection means for detecting a current flowing between the electrode means and the burner, potential detection means for detecting a potential in the flame, potential difference detection means for detecting a potential difference,
The apparatus includes arithmetic means for calculating a flame impedance, threshold value selecting means for selecting a threshold value of the flame impedance, and combustion control means for controlling combustion.

The variable voltage supply means supplies a plurality of different constant DC voltages between the electrode means and the burner.

The calculating means calculates a flame impedance from a current flowing when a plurality of different DC voltages are supplied between the electrode means and the burner and a potential difference detected by the potential difference detecting means.

The flame impedance can be calculated from the current and the potential difference detected when the variable voltage supply means supplies a plurality of different constant voltages between the electrode means and the burner. Since the flame impedance is constant even if silicon oxide is formed on the electrode means or the burner, the combustion state can be accurately determined.

The threshold value selecting means selects a threshold value of the flame impedance according to the current range.

In the current-potential difference characteristics during normal combustion, the flame impedance changes depending on the current range, but when the current decreases to a certain value due to the formation of silicon oxide, the optimum flame impedance threshold is selected by the threshold selection means. Is selected, the life of the combustion device with respect to silicon oxide can be further extended.

The potential difference detecting means detects a potential difference generated between the electrode means and the potential detecting means.

A flame between the electrode means and the potential detecting means is obtained from a current detected when a different voltage is supplied between the electrode means and the burner by the variable voltage supplying means and a potential difference generated between the electrode means and the potential detecting means. The impedance can be calculated. This flame impedance is constant if combustion is normal, even if a large amount of silicon oxide is formed on the burner side, so that the combustion state can be accurately determined.

The potential difference detecting means detects a potential difference generated between the potential detecting means and the burner.

The flame impedance between the potential detecting means and the burner is determined from the current detected when a different voltage is supplied between the electrode means and the burner and the potential difference between the potential detecting means and the burner by the variable voltage supplying means. Can be calculated. This flame impedance is constant if combustion is normal even if a large amount of silicon oxide is formed on the electrode means side, so that the combustion state can be accurately determined.

The potential detecting means comprises a first potential detecting means and a second potential detecting means. Further, the potential difference detecting means is a first potential difference detecting means for detecting a potential difference generated between the first potential detecting means and the second potential detecting means.

The variable voltage supply means detects the current detected when a different voltage is supplied between the electrode means and the burner, the first potential detection means, and the potential difference generated between the second potential detection means. The flame impedance between the detection means and the second potential detection means can be calculated. The flame impedance is constant if combustion is normal regardless of whether silicon oxide is formed on the burner side or on the electrode means side, so that the combustion state can be accurately determined.

The potential difference detecting means detects the potential difference between the first potential detecting means and the second potential detecting means, and detects the potential difference between the second potential detecting means and the burner. It comprises second potential difference detecting means.

The current detected when a different voltage is supplied between the electrode means and the burner by the variable voltage supply means, the potential difference between the first potential detection means and the second potential detection means, and the second potential detection means The flame impedance between the first potential detecting means and the second potential detecting means and the impedance between the second potential detecting means and the burner can be calculated from the potential difference generated between the first potential detecting means and the burner. The flame impedance between the first potential detection means and the second potential detection means is constant if combustion is normal, regardless of whether silicon oxide is formed on the burner side or on the electrode means side. Can be determined.

Since the impedance between the second potential detecting means and the burner depends on the amount of silicon oxide formed on the burner, the amount of silicon oxide formed on the burner can be detected from the detected impedance. can do.

By connecting the second potential difference detecting means between the second potential detecting means and the burner, the insulation of the first potential detecting means and the second potential detecting means can be improved, and Since there is no need to take measures such as an insulating coating provided to prevent deterioration of insulation due to condensation or the like, costs can be reduced.

The potential difference detecting means includes a third potential difference detecting means for detecting a potential difference between the electrode means and the first potential detecting means, and a second potential difference detecting means for detecting a potential difference between the second potential detecting means and the burner. Consisting of means.

The current detected when a different voltage is supplied between the electrode means and the burner by the variable voltage supply means, the potential difference between the second potential detection means and the burner, and the potential difference between the electrode means and the first potential detection means. , The impedance between the second potential detecting means and the burner and the impedance between the electrode means and the first potential detecting means can be calculated. Further, the entire impedance between the electrode means and the burner is determined from the voltage and current applied between the electrode means and the burner, and the first potential is determined from the impedance between the second potential detection means and the burner and the impedance between the electrode means and the first potential detection means. The flame impedance between the detection means and the second potential detection means can be calculated. The flame impedance between the first potential detecting means and the second potential detecting means is constant if combustion is normal regardless of whether silicon oxide is formed on the burner side or on the electrode means side. Can be determined.

The impedance between the second potential detecting means and the burner and the impedance between the electrode means and the first potential detecting means depend on the amounts of silicon oxide formed on the burner and the electrode means, respectively. The amount of silicon oxide formed on the burner and the electrode means can be detected from the impedance thus obtained.

The potential difference detecting means detects a potential difference between the electrode means and the first potential detecting means, and detects a potential difference between the first potential detecting means and the second potential detecting means. It comprises first potential difference detecting means.

The current detected when a different voltage is supplied between the electrode means and the burner, the potential difference between the electrode means and the first potential detecting means, and the potential difference between the first potential detecting means and the second potential detecting means. The impedance between the electrode means and the first potential detecting means and the flame impedance between the first potential detecting means and the second potential detecting means can be calculated from the potential difference between the detecting means. The flame impedance between the first potential detecting means and the second potential detecting means is constant if combustion is normal regardless of whether silicon oxide is formed on the burner side or on the electrode means side. Can be determined.

Since the impedance between the electrode means and the first potential detecting means depends on the amount of silicon oxide formed on the electrode means, the impedance of the silicon oxide formed on the electrode means is determined from the detected impedance. The amount can be detected.

Further, the tip portions of the first potential detecting means and the second potential detecting means are provided in the outer flame of the flame formed in the burner, and are provided with a potential difference between the electrode means and the first potential detecting means. Comprising a potential difference ratio calculating means for calculating a potential difference ratio from a potential difference generated between the first potential detecting means and the second potential detecting means, and a secondary air detecting means for detecting a change in secondary air from the potential difference ratio. It is.

The tip portions of the first potential detecting means and the second potential detecting means are disposed in an external flame formed by a chemical reaction with the secondary air, and a potential difference ratio is calculated by a potential difference ratio calculating means. . Since the ratio of the potential difference depends on the amount of the secondary air, the fluctuation of the secondary air can be detected by the secondary air detecting means.

[0037]

Embodiments of the present invention will be described below with reference to the drawings.

(Embodiment 1) FIG. 1 is a schematic configuration diagram of a combustion apparatus according to Embodiment 1 of the present invention. In FIG. 1, reference numeral 1 denotes a burner for burning fuel, and an electrode means 3 is provided in contact with a flame 2 formed on the burner 1. And burner 1
A variable voltage supply means 16 to which a plurality of different DC voltages can be applied is connected between the power supply and the electrode means 3. Further, a current detecting means 5 is connected to detect a current (I) flowing between the burner 1 and the electrode means 3. A potential detecting means 17 is provided in contact with the flame 2 to detect a potential in the flame 2. A potential difference detecting means 18 is connected to detect a potential difference (Vf1) between the electrode means 3 and the potential detecting means 17. Further, the flame impedance (Rf1d) is calculated from the detected current (I) and potential difference (Vf1).
, A threshold selecting means 20 for selecting an optimum flame impedance threshold based on the detected current (I), and a combustion state is determined from the flame impedance (Rf1d). And combustion control means 6 for forcibly stopping combustion if abnormal.

Kerosene as fuel is supplied to the vaporizing element 21 by an electromagnetic pump or the like. The kerosene is heated by a heater 9 buried in a vaporizing cylinder 7 to be vaporized into a fuel gas,
The fuel is further injected into the burner 1. At this time, the primary air is supplied from the primary air through hole 10 by the ejector action and mixed with the fuel gas to become a premixed gas. The premixed gas is ignited by an ignition rod 15 fixed to a burner base 14 when passing through the burner 1 and passing through the flame hole 13,
A flame 2 is formed.

The flame 2 is an internal flame 2a formed in the flame hole 13 by a combustion reaction of the primary air for combustion premixed with the fuel gas.
And an outer flame 2b formed outside the inner flame 2a by a combustion reaction of the surrounding secondary air for combustion. The inner flame 2a and the outer flame 2b contain a large amount of charged particles such as thermally ionized ions and electrons. In particular, the charged particle density of the inner flame 2a is higher than that of the outer flame 2b. The electrode means 3 and the potential detecting means 17 were disposed in contact with the end flame 2a having a high charged particle density.

According to the above configuration, when a constant voltage is applied between the burner 1 and the electrode means 3 by the DC power supply as the variable voltage supply means 16, charged particles (ions and electrons) in the flame 2 are applied.
Are accelerated and move toward the burner 1 or the electrode means 3, respectively, and a constant current (I) according to the combustion flows between the burner 1 and the electrode means 3. At this time, charged particles thermally ionized are distributed between the electrode means 3 and the burner 1, and the potential is detected by the potential detecting means 17. And the electrode means 3
A potential difference (Vf1) generated between the potential difference detecting means 17 and the potential detecting means 17 is detected by the potential difference detecting means 18.

Since the combustion apparatus of the present invention uses the variable voltage supply means 16 which can supply a plurality of different constant voltages between the burner 1 and the electrode means 3, at least the current (I) and the potential difference (Vf1) are respectively reduced. Two or more points can be detected. Then, the impedance between the electrode means 3 and the potential detecting means 17 can be obtained from the potential difference (Vf1) and the current (I) at the two points by using the calculating means 19.

When a volatile organic silicone compound contained in a hairdressing spray or the like is mixed in the combustion air, a chemical reaction occurs with oxygen in the combustion flame to form an insulating silicon oxide. Silicon oxide forms a film at different places depending on the amount of combustion. When the amount of combustion is low, silicon oxide is mainly formed mainly on the burner 1 side. At this time, the electrode means 3
Since the amount of silicon oxide formed on the side of the potential detecting means 17 is much smaller than that formed on the side of the burner 1, the increase in impedance due to the formation of the silicon oxide is almost negligible. 17
The impedance between them corresponds to (Rf1d) the flame impedance indicating the state of the flame between them.

In order to examine the basic characteristics of the combustion apparatus of the present invention, the current (I) -potential difference (Vf1) characteristics when normally burning at a combustion amount of 2,500 kcal / h were measured. When the supply voltage of the variable voltage supply means 16 is changed, the electrode means 3 and the burner 1 obtained at each supply voltage are obtained.
FIG. 2 shows the relationship between the current (I) flowing therebetween and the potential difference (Vf1) generated between the electrode means 3 and the potential detecting means 17. FIG. 2 shows that the potential difference (Vf1) changes linearly with respect to the current (I). The slope of this straight line represents the flame impedance (Rf1d) between the electrode means 3 and the potential detecting means 17. Also, it can be seen that this straight line does not pass through the origin and has an intercept (a). When the voltage supplied between the burner 1 and the electrode means 3 is constant, the flame impedance (Rf1d) cannot be directly obtained, so that the apparent flame impedance (Rf1c) has to be obtained. The flame impedance (Rf1c) is obtained by subtracting the intercept (a) obtained from the I-Vf1 characteristic from the potential difference (Vf1) between the electrode means 3 and the potential detecting means 17 as shown in Expression (1), and calculating the burner 1 and the electrode. It can be obtained by dividing by the current (I) flowing between the means 3.

[0045]

(Equation 1)

Since the flame impedance (Rf1c) is constant even if the current (I) decreases if the combustion is normal, it is possible to accurately judge the combustion without being affected by the formation of silicon oxide. it can.

However, even if the actual flame impedance (Rf1d) is constant, the intercept (a) may fluctuate due to a slight displacement of the potential detection means 17 or the like or a leak current. The impedance (Rf1c) could not be determined accurately.

According to the combustion apparatus of the present invention, the variable voltage supply means 16 capable of supplying a plurality of different constant voltages between the burner 1 and the electrode means 3 is used to detect at least two points of current and potential difference, respectively. The currents (I1 and I2) detected by the current detecting means 5
And the potential difference detected by the potential difference detecting means 18 (Vf11
And Vf12), the flame impedance (Rf1d) can be obtained directly using equation (2).

[0049]

(Equation 2)

This flame impedance (Rf1d) is constant if combustion is normal even if a large amount of silicon oxide is formed on the burner 1 side, and the flame impedance can be calculated without using an intercept. The state can be determined with higher accuracy.

When the silicon oxide starts to be formed on the burner 1, the current (I) decreases while maintaining the slope of the straight line. However, as can be seen from the current (I) -potential difference (Vf1) characteristic shown in FIG. 2, the slope changes when the current (I) decreases and reaches a certain value (Is). According to the present invention,
Since the threshold value selecting means 20 for selecting the threshold value of the flame impedance according to the current range is provided, even if the current (I) decreases due to the formation of silicon oxide, the optimum threshold value of the flame impedance can be selected. The combustion state can be accurately determined stably for a longer period of time.

(Embodiment 2) FIG. 3 is a schematic structural view of a combustion apparatus according to Embodiment 2 of the present invention. FIG. 3 differs from the first embodiment in that the potential difference detecting means 18 detects a potential difference (V2b) between the burner 1 and the potential detecting means 17. The components having the same reference numerals as those in the first embodiment have the same structure, and the description will be omitted.

According to the combustion apparatus of Embodiment 2 of the present invention, the currents (I1 and
The flame impedance (R2bd) between the potential detecting means 17 and the burner 1 can be obtained by using equation (3) from I2) and the potential difference (V2b1 and V2b2) between the potential detecting means 17 and the burner 1.

[0054]

(Equation 3)

The present invention has a great effect when a large amount of silicon oxide is formed on the electrode means 3 side. The flame impedance (R2bd) is constant if combustion is normal, and the flame impedance can be reduced without using a slice. Since it can be calculated, the combustion state can be accurately determined.

(Embodiment 3) FIG. 4 is a schematic structural view of a combustion apparatus according to Embodiment 3 of the present invention. FIG. 4 is different from the first embodiment in that the potential detecting means is the first potential detecting means 17a.
And the second potential detecting means 17b, and the potential difference detecting means 18 is to detect a potential difference (V12) between the first potential detecting means 17a and the second potential detecting means 17b. The components having the same reference numerals as those of the first embodiment have the same structure,
Description is omitted.

According to the combustion apparatus of Embodiment 3 of the present invention, the currents (I1 and I1) detected at a plurality of different constant voltages are
I2) and the potential difference (V1
21 and V122), the flame impedance (R12d) between the first potential detecting means 17a and the second potential detecting means 17b can be obtained from equation (4).

[0058]

(Equation 4)

The present invention has a large effect even if a large amount of silicon oxide is formed in either the burner 1 or the electrode means 3.
The flame impedance (R12d) is constant if the combustion is normal, and the flame impedance can be calculated without using a fluctuating intercept, so that the combustion state can be accurately determined.

(Embodiment 4) FIG. 5 is a schematic structural view of a combustion apparatus according to Embodiment 4 of the present invention. FIG. 5 is different from the first embodiment in that the potential difference detecting means is the first potential detecting means 17a.
Potential difference detecting means 18a for detecting a potential difference (V12) between the first and second potential detecting means 17b and second potential difference detecting means 18b for detecting a potential difference (V2b) between the burner 1 and the second potential detecting means 17b. It is about to become.

The components having the same reference numerals as in the first embodiment have the same structure, and the description is omitted. According to the combustion apparatus of Embodiment 4 of the present invention, the currents (I1 and I2) detected at a plurality of different constant voltages, the potential differences (V121 and V122) detected by the first potential difference detecting means 18a, and the second potential difference detection The potential difference (V2b1 and V2b
2), the flame impedance (R12d) between the first potential detecting means 17a and the second potential detecting means 17b and the impedance (R12d) between the burner 1 and the second potential detecting means 17b from the equations (3) and (4), respectively. R2bd). First potential detecting means 17a and second potential detecting means 1
Regarding the flame impedance (R12d) between 7b, the flame impedance can be calculated stably regardless of which side of the silicon oxide is formed on the burner 1 or the electrode means 3, so that the combustion state can be accurately determined. it can.

Then, the burner 1 and the second potential detecting means 17
Since the impedance between R and B (R2bd) depends on the amount of silicon oxide formed on the burner 1, it is possible to detect the amount of silicon oxide formed on the burner 1 from the detected impedance (R2bd). it can.

By connecting the second potential difference detecting means 18b between the burner 1 and the second potential detecting means 17b, the first potential detecting means 17a and the second potential detecting means 1b are connected.
Since the insulating property of 7b is improved, measures such as an insulating coating provided for preventing the insulating property from deteriorating due to dew condensation on the circuit board become unnecessary, and the cost can be reduced.

(Embodiment 5) FIG. 6 is a schematic structural view of a combustion apparatus according to Embodiment 5 of the present invention. 6 is different from the first embodiment in that the potential difference detecting means includes a second potential difference detecting means 18b for detecting a potential difference (V2b) between the burner 1 and the second potential detecting means 17b, an electrode means 3 and a first potential detecting means. Means 17a
Potential difference detecting means 18 for detecting the potential difference (Vf1) between
c. The components having the same reference numerals as those in the first embodiment have the same structure, and the description will be omitted.

According to the combustion apparatus of Embodiment 5 of the present invention, the currents (I1 and I1) detected at a plurality of different constant voltages are detected.
I2) and the potential difference (V2b1 and V2b2) detected by the second potential difference detecting means 18b and the third potential difference detecting means 18c
(3) and (2), respectively, using the potential difference (Vf11 and Vf12) detected by the equation (3) and (2), the impedance (R2bd) between the burner 1 and the second potential detecting means 17b, and the electrode means 3 and the first potential detecting means 17a. The impedance between them (Rf1d) can be determined. Further, the potential difference (V2b) detected by the second potential difference detecting means 18b and the potential difference (Vf1) detected by the third potential difference detecting means 18c are subtracted from the voltage (Vfb) applied between the electrode means 3 and the burner 1, The potential difference (V12) between the first potential detecting means 17a and the second potential detecting means 17b can be obtained,
From equation (4), the flame impedance (R12d) can be calculated. Regardless of which side of the burner 1 and the electrode means 3 the silicon oxide is formed on the flame impedance (R12d), the flame impedance can be calculated stably, so that the combustion state can be accurately determined.

Then, the burner 1 and the second potential detecting means 17
The impedance (R2bd) between the electrodes b and the impedance (Rf1d) between the electrode means 3 and the first potential detecting means 17a depend on the amount of silicon oxide formed on the burner 1 and the electrode means 3, respectively. The amount of silicon oxide formed on the burner 1 and the electrode means 3 can be detected from the impedance (Rf1d and R2bd).

(Embodiment 6) FIG. 7 is a schematic structural view of a combustion apparatus according to Embodiment 6 of the present invention. FIG. 7 is different from the first embodiment in that the potential difference detecting means is the first potential detecting means 17a.
Potential difference detecting means 18a for detecting a potential difference (V12) between the first and second potential detecting means 17b, and third potential difference detecting means 18c for detecting a potential difference (Vf1) between the electrode means 3 and the first potential detecting means 17a. It consists of

The first potential detecting means 17a and the second potential detecting means 17b are disposed on the outer flame 2b of the flame 2 formed in the burner 1, and the first potential detecting means 17a and the second potential detecting means 17b A potential difference ratio calculating means 22 for calculating a potential difference ratio (Vf1 / V12) from the potential difference (V12) between the electrode means 3 and the potential difference (Vf1) between the electrode means 3 and the first potential detecting means 17a.
And secondary air detecting means 23 for detecting the fluctuation of the secondary air from the potential difference ratio (Vf1 / V12) and controlling the combustion. The components having the same reference numerals as those in the first embodiment have the same structure, and the description will be omitted.

According to the combustion apparatus of Embodiment 6 of the present invention, the currents (I1 and I1) detected at a plurality of different constant voltages are detected.
I2) and the potential difference (V121 and V122) detected by the first potential difference detecting means 18a and the third potential difference detecting means 18c
(4) and (2) using the potential difference (Vf11 and Vf12) detected by
The flame impedance (R12d) between 7a and the second potential detecting means 17b and the impedance (Rf1d) between the electrode means 3 and the first potential detecting means 17a can be obtained. The flame impedance (R12d) between the first potential detecting means 17a and the second potential detecting means 17b can stably calculate the flame impedance regardless of whether the silicon oxide is formed on the burner 1 or the electrode means 3. Therefore, the combustion state can be accurately determined.

The electrode means 3 and the first potential detecting means 1
Since the impedance (Rf1d) between the electrodes 7a depends on the amount of silicon oxide formed on the electrode means 3, the amount of silicon oxide formed on the electrode means 3 is detected based on the detected impedance (Rf1d). be able to.

Then, the first potential detecting means 17a and the second potential detecting means 17b are disposed in the outer flame 2b formed by the chemical reaction with the secondary air, and the potential difference ratio (Vf1 / V12) is calculated. The relationship between the ratio of the potential difference (Vf1 / V12) and the amount of secondary air at a combustion amount of 2,500 kcal / h was examined using the combustion apparatus of the present invention. FIG. 8 shows the measurement results. From FIG. 8, the ratio of the potential difference (Vf1 /
V12) depends on the amount of secondary air and changes linearly. This is because when the secondary air fluctuates, the inner flame 2a hardly changes, and only the outer flame 2b changes. Therefore, the inner flame 2a is detected by the first potential detecting means 17a and the second potential detecting means 17b disposed on the outer flame 2b. Since the potential distribution changes remarkably, and particularly the potential difference between the electrode means 3 and the first potential detecting means 17a greatly changes, the fluctuation of the secondary air is detected by detecting the ratio (Vf1 / V12) of the potential difference. can do.

[0072]

As is apparent from the above description, the following effects can be obtained according to the combustion apparatus of the present invention.

(1) The flame impedance can be calculated from the current and the potential difference detected when the variable voltage supply means supplies a plurality of different constant voltages between the burner and the electrode means, without using the intercept. The flame impedance is constant if combustion is normal even when silicon oxide is formed, so that the combustion state can be accurately determined.

(2) In the current-potential difference characteristics during normal combustion, the slope of the straight line representing the flame impedance changes depending on the current range. When the current decreases to a certain value due to the formation of silicon oxide, the threshold value is selected. By selecting the optimal flame impedance threshold by the means, the life of the combustion device for silicon oxide can be extended.

(3) A flame between the electrode means and the potential detecting means is obtained from a current detected when a plurality of different constant voltages are supplied between the electrode means and the burner and a potential difference between the electrode means and the potential detecting means. It is possible to calculate the impedance, and this flame impedance is constant if combustion is normal, even if a large amount of silicon oxide is formed on the burner side.
The combustion state can be accurately determined.

(4) The flame impedance between the potential detecting means and the burner is determined from the current detected when a plurality of different constant voltages are supplied between the electrode means and the burner and the potential difference generated between the potential detecting means and the burner. This flame impedance is constant when combustion is normal, even if a large amount of silicon oxide is formed on the electrode means side, so that the flame impedance can be calculated without using a slice that may fluctuate. Can be accurately determined.

(5) The first potential detecting means is obtained from a current detected when a plurality of different constant voltages are supplied between the electrode means and the burner and a potential difference generated between the first potential detecting means and the second potential detecting means. And the flame impedance between the second potential detecting means and the flame impedance is constant if combustion is normal, regardless of whether silicon oxide is formed in the burner or the electrode means in large amounts. It is possible to accurately determine the combustion state without using a section that may cause the combustion.

(6) The current detected when a plurality of different constant voltages are supplied between the electrode means and the burner, the potential difference generated between the first potential detecting means and the second potential detecting means, and the second potential detecting The flame impedance between the first potential detecting means and the second potential detecting means and the impedance between the second potential detecting means and the burner can be calculated from the potential difference generated between the means and the burner. The flame impedance between the first potential detecting means and the second potential detecting means may be fluctuated because the combustion is normal regardless of the amount of silicon oxide formed on either side of the burner or the electrode means. The combustion state can be accurately determined without using a certain section.

(7) Since the impedance between the second potential detecting means and the burner depends on the amount of silicon oxide formed on the burner, the impedance of the silicon oxide formed on the burner is determined from the detected impedance. The amount can be detected.

(8) By connecting the second potential difference detecting means between the burner and the second potential detecting means, the insulation of the first potential detecting means and the second potential detecting means can be improved, Since there is no need to take measures such as an insulating coating provided to prevent deterioration of insulation due to dew condensation on the substrate, the cost can be reduced.

(9) The current detected when a plurality of different constant voltages are supplied between the electrode means and the burner, the potential difference generated between the second potential detecting means and the burner, and the electrode means and the first potential detecting means. The impedance between the burner and the second potential detecting means and the impedance between the electrode means and the first potential detecting means can be calculated from the potential difference generated between them. Further, the entire impedance between the electrode means and the burner is determined from the voltage and current applied between the electrode means and the burner, and the first potential is determined from the impedance between the second potential detection means and the burner and the impedance between the electrode means and the first potential detection means. The flame impedance between the detection means and the second potential detection means can be calculated. The flame impedance between the first potential detecting means and the second potential detecting means may be fluctuated because the combustion is normal regardless of whether the silicon oxide is formed on either side of the burner and the electrode means. The combustion state can be accurately determined without using the intercept.

(10) The impedance between the burner and the second potential detecting means and the impedance between the electrode means and the first potential detecting means depend on the amounts of silicon oxide formed on the burner and the electrode means, respectively. So
The amount of silicon oxide formed on the burner and the electrode means can be detected from the detected impedance.

(11) The current detected when a plurality of different constant voltages are supplied between the electrode means and the burner, the potential difference between the electrode means and the first potential detecting means, and the potential difference between the first potential detecting means and the second potential detecting means. The impedance between the electrode means and the first potential detecting means and the flame impedance between the first potential detecting means and the second potential detecting means can be calculated from the potential difference generated between the potential detecting means. The flame impedance between the first potential detecting means and the second potential detecting means may be fluctuated because the combustion is normal regardless of whether the silicon oxide is formed on either side of the burner and the electrode means. The combustion state can be accurately determined without using the intercept.

(12) Since the impedance between the electrode means and the first potential detecting means depends on the amount of silicon oxide formed on the electrode means, the silicon impedance formed on the electrode means is determined based on the detected impedance. The amount of oxide can be detected.

(13) Then, the first potential detecting means and the second potential detecting means are arranged in the outer flame formed by the chemical reaction with the secondary air, and the potential difference ratio is calculated by the potential difference ratio calculating means. Since the ratio of the potential difference depends on the amount of the secondary air, the fluctuation of the secondary air can be detected by the secondary air detecting means.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a combustion device according to a first embodiment of the present invention.

FIG. 2 is a current-potential difference characteristic diagram of Example 1.

FIG. 3 is a schematic configuration diagram of a combustion device according to a second embodiment of the present invention.

FIG. 4 is a schematic configuration diagram of a combustion device according to a third embodiment of the present invention.

FIG. 5 is a schematic configuration diagram of a combustion device according to a fourth embodiment of the present invention.

FIG. 6 is a schematic configuration diagram of a combustion apparatus according to a fifth embodiment of the present invention.

FIG. 7 is a schematic configuration diagram of a combustion apparatus according to a sixth embodiment of the present invention.

FIG. 8 is a graph showing secondary air fluctuation characteristics according to the sixth embodiment.

FIG. 9 is a front sectional view of a conventional combustion device.

[Explanation of symbols]

 Reference Signs List 1 burner 2 flame 3 electrode means 5 current detection means 6 combustion control means 16 variable voltage supply means 17 potential detection means 17a first potential detection means 17b second potential detection means 18 potential difference detection means 18a first potential difference detection means 18b second potential difference Detecting means 18c third potential difference detecting means 19 calculating means 20 threshold value selecting means 22 potential difference ratio calculating means 23 secondary air detecting means

Claims (12)

[Claims] A burner; electrode means disposed in contact with a flame formed on the burner; variable voltage supply means for supplying a voltage between the electrode means and the burner; A current detecting means for detecting a current flowing between the burners, a potential detecting means for detecting a potential in the flame, a potential difference detecting means for detecting a potential difference, a calculating means for calculating a flame impedance, and a threshold value of the flame impedance. A combustion apparatus comprising: a threshold value selecting unit that performs combustion; and a combustion control unit that controls combustion. 2. The combustion apparatus according to claim 1, wherein the variable voltage supply means supplies a plurality of different DC voltages between the electrode means and the burner. 3. The combustion apparatus according to claim 1, wherein the calculating means calculates the flame impedance from a current flowing when a plurality of different DC voltages are supplied between the electrode means and the burner and a potential difference detected by the potential difference detecting means. 4. The combustion apparatus according to claim 1, wherein said threshold value selecting means selects a threshold value of the flame impedance according to a current range. 5. The combustion apparatus according to claim 1, wherein the potential difference detecting means detects a potential difference generated between the electrode means and the potential detecting means. 6. The combustion apparatus according to claim 1, wherein the potential difference detecting means detects a potential difference generated between the potential detecting means and the burner. 7. The combustion apparatus according to claim 1, wherein the potential detecting means comprises a first potential detecting means and a second potential detecting means. 8. The combustion apparatus according to claim 1, wherein the potential difference detecting means is a first potential difference detecting means for detecting a potential difference generated between the first potential detecting means and the second potential detecting means. 9. A potential difference detecting means for detecting a potential difference between the first potential detecting means and the second potential detecting means, and a potential difference between the second potential detecting means and the burner. 2. The method according to claim 1, further comprising a second potential difference detecting means.
Or the combustion device according to 7. 10. A potential difference detecting means for detecting a potential difference between the electrode means and the first potential detecting means, and a second potential difference detecting means for detecting a potential difference between the second potential detecting means and the burner. The combustion device according to claim 1 or 7, comprising means. 11. A potential difference detecting means for detecting a potential difference between the electrode means and the first potential detecting means, and detecting a potential difference between the first potential detecting means and the second potential detecting means. 2. The method according to claim 1, further comprising first potential difference detecting means.
Or the combustion device according to 7. 12. The tip of the first potential detecting means and the tip of the second potential detecting means are disposed in an outer flame of a flame formed in the burner, and have a potential difference between the electrode means and the first potential detecting means. A potential difference ratio calculating means for calculating a potential difference ratio from a potential difference generated between the first potential detecting means and the second potential detecting means,
The combustion apparatus according to claim 1, further comprising a secondary air detection unit configured to detect a change in secondary air from a ratio of the potential difference.