JP2008128554A - Combustion device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a combustion device including a detecting means capable of surely detecting shortage of air quantity to the fuel gas quantity. <P>SOLUTION: In this combustion device, he mixed air, which is formed by mixing the primary air with a fuel gas to be short of oxygen, is primarily burned, and further the secondary air is supplied to perform the secondary combustion. A first conductive member 65 is disposed in a flame 24 of the primary combustion, a second conductive member 66 is disposed in a flame 68 of the secondary combustion, and further a common alternating current power supply 50 for applying voltage to the flame 24 of the primary combustion and the flame 68 of the secondary combustion is provided. A value of a first current flowing through the flame 24 of the primary combustion and a value of a second current flowing through the flame 68 of the secondary combustion are detected to determine the combustion state by a calculation formula including the sum of the detected first current value and second current value and the ratio of the first current or the second current to a difference between the first current and the second current. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a combustion apparatus, and more particularly to a combustion apparatus recommended for use in a water heater or a bath apparatus.

  Combustion devices are the main components of water heaters and bath devices, and are widely used not only in factories but also in general households. In a conventional combustion device, a thermocouple is used as a means for diagnosing the combustion state. However, since a thermocouple cannot detect a shortage of the amount of air supplied, it has recently been in a flame instead of a thermocouple. A conductive member (hereinafter referred to as an ion probe) for detecting the conductivity of the ionized unburned component of the existing fuel is exclusively employed. Since ions are present in the flame, the flame is a weak plasma body.

For example, Patent Document 1 discloses a combustion apparatus that detects the combustion state using the conductivity in the flame. The combustion apparatus disclosed in Patent Document 1 is provided with an air-fuel ratio detection apparatus including two ion probes. In the air-fuel ratio detection device for a combustion apparatus of Patent Document 1, ion probes are arranged near the flame hole and near the outside of the flame, respectively, and the corresponding air-fuel ratio is calculated from the current value detected by the ion probe. In the combustion apparatus disclosed in Patent Document 1, a DC power source is used.
Japanese Patent Publication No. 4-37332

  By the way, although the air-fuel ratio detection device of the combustion apparatus disclosed in Patent Document 1 can detect the shortage of the air amount with respect to the fuel gas amount, since a DC power source is adopted as the power source, one flame ion is present. It moves only in the direction and causes ion wind in the same direction. Therefore, the shape of the flame is distorted due to the influence of the ion wind, which may cause a misfire.

  In addition, for a specific gas type, it is possible to find a correlation between the ratio of the current detection value detected by both ion probes and the air-fuel ratio, but the ratio is the gas type (type of combustible component). Therefore, the air-fuel ratio detection device for a combustion apparatus disclosed in Patent Document 1 cannot cope with a universal burner (a burner corresponding to various fuel gases).

  Therefore, an object of the present invention is to provide a combustion apparatus that can reliably detect a shortage of the air amount relative to the fuel gas amount.

  The invention according to claim 1 for solving the above-mentioned problem is a combustion in which an oxygen-deficient mixture formed by mixing primary air and fuel gas undergoes primary combustion and further receives secondary air to perform secondary combustion. In the apparatus, a first conductive member is disposed in the primary combustion flame, a second conductive member is disposed in the secondary combustion flame, and a voltage is applied to the primary combustion flame and the secondary combustion flame. Providing a common AC power source to be applied, detecting a first current value flowing through the flame of the primary combustion and a second current value flowing through the flame of the secondary combustion, and detecting the detected first current value and the second current A combustion apparatus for determining a combustion state by a calculation formula including a sum of values, a first current value, a second current value, and a ratio of a difference between the second current value and the first current value. is there.

  That is, two conductive members are installed in two locations, the upstream primary flame (primary combustion flame) and the downstream secondary flame (secondary combustion flame), respectively, and the amount of air supplied is insufficient. Is detected. Incidentally, if the amount of supplied air is insufficient, the combustion speed of the primary flame on the upstream side becomes slow, the primary flame expands to the downstream side, and the content of flame ions in the secondary flame on the downstream side increases. The conductivity in the next flame increases. Therefore, when the amount of air is insufficient, the second current value of the secondary flame increases.

  In the invention of claim 1, since an AC power supply is used, the flame ions of the fuel gas in the flame are not biased to a specific location, and the conductivity of the flame can be detected with the flame shape stabilized. The combustion state can be determined without adversely affecting the combustion state.

  In the first aspect of the present invention, the ratio of the sum of the first current value and the second current value, the first current value, the second current value, and the difference between the second current value and the first current value is calculated. By determining the combustion state with the calculation formula including it, it is possible to reliably detect abnormal combustion due to air shortage. Furthermore, the combustion state of the universal burner corresponding to various fuel gases can be determined appropriately.

  According to a second aspect of the present invention, there is provided a combustion apparatus in which an oxygen-deficient mixture obtained by mixing primary air and fuel gas undergoes primary combustion and further receives secondary air to perform secondary combustion. A first conductive member is disposed in the flame, a second conductive member is disposed in the secondary combustion flame, and a common AC power source for applying a voltage to the primary combustion flame and the secondary combustion flame is provided. A first current value flowing through the primary combustion flame and a second current value flowing through the secondary combustion flame, and a first A / D conversion value and a second current value of the first current value Of the second A / D conversion value, the first A / D conversion value, the second A / D conversion value, and the difference between the second A / D conversion value and the first A / D conversion value. It is a combustion apparatus characterized by determining a combustion state with a calculation formula including a ratio.

  Since the invention of claim 2 uses an AC power supply as in the invention of claim 1, flame ions in the flame are not biased to a specific location, and the flame conduction is maintained in a state where the flame shape is stabilized. The combustion state can be determined without adversely affecting the combustion state. In particular, according to the second aspect of the present invention, only one input terminal of the computer (microcomputer) is required by calculating using the first A / D conversion value and the second A / D conversion value of both current values. The (first and second) current values referred to here refer to current signals.

  According to a third aspect of the present invention, there is provided a combustion apparatus in which an oxygen-deficient mixture formed by mixing primary air and fuel gas undergoes primary combustion and further receives secondary air to perform secondary combustion. A first conductive member is disposed in the flame, a second conductive member is disposed in the secondary combustion flame, and a common AC power source for applying a voltage to the primary combustion flame and the secondary combustion flame is provided. A first current value flowing in the primary combustion flame and a second current value flowing in the secondary combustion flame are detected, and the first current value and the second conductivity detected by the first conductive member are detected. Depending on the sum of the second current value, the first current value, or the second current value detected by the conductive member, and the ratio of the difference between the second current value and the first current value, the supply air amount and the supply fuel It is a combustion apparatus characterized by controlling at least one of gas amounts.

  In the invention of claim 3, the first current value flowing through the primary combustion flame and the second current value flowing through the secondary combustion flame are detected, and the first current value detected by the first conductive member and the second current value detected by the first conductive member are detected. Depending on the sum of the second current values detected by the two conductive members, the first current value, the second current value, and the ratio of the difference between the second current value and the first current value, Since at least one of the supplied fuel gas amounts is controlled, the abnormal combustion state can be quickly eliminated.

  According to a fourth aspect of the present invention, there is provided a combustion apparatus in which an oxygen-deficient mixture formed by mixing primary air and fuel gas undergoes primary combustion, and further receives secondary air to perform secondary combustion. A first conductive member is disposed in the flame, a second conductive member is disposed in the secondary combustion flame, and a common AC power source for applying a voltage to the primary combustion flame and the secondary combustion flame is provided. A first current value detected by the first conductive member is detected by detecting a first current value flowing through the flame of the primary combustion and a second current value flowing through the flame of the secondary combustion. / D conversion value and the sum of the second A / D conversion value of the second current value detected by the second conductive member, one of the first A / D conversion value, the second A / D conversion value, Depending on the ratio of the difference between the second A / D conversion value and the first A / D conversion value, the amount of the supply air amount and the supply fuel gas amount is small. A combustion apparatus, which comprises controlling one Kutomo.

  In the invention of claim 4, the first A / D conversion value of the first current value detected by the first conductive member and the second A / D conversion value of the second current value detected by the second conductive member. Depending on the sum, the first A / D conversion value, the second A / D conversion value, and the ratio of the difference between the second A / D conversion value and the first A / D conversion value, Since at least one of the supplied fuel gas amounts is controlled, the abnormal combustion state can be quickly eliminated. The (first and second) current values referred to here refer to current signals.

  In the combustion apparatus according to any one of claims 1 to 4, it is preferable that the frequency of the AC power source is a high frequency in the range of 50 to 110 KHz. Also, errors due to AC power supply noise, voltage fluctuations, and frequency fluctuations that have the same effect on the first current value and the second current value can be canceled out and eliminated. Can be detected well. Therefore, in the combustion apparatus according to the third and fourth aspects of the invention, the abnormal combustion state can be detected with high accuracy, and the abnormal combustion state can be quickly eliminated.

  When the present invention is implemented, an abnormal combustion state due to air shortage can be reliably detected. In addition, since the combustion apparatus embodying the present invention can achieve the above-mentioned effects regardless of the type of fuel gas, the present invention is implemented with a universal burner that uses different types of fuel gas in the same combustion apparatus. Is possible.

  Examples of the present invention will be described below. First, the schematic configuration and basic functions of the present invention will be described with reference to the schematic diagram of FIG. 1, and then the configuration related to the present invention will be described in detail with reference to FIG. FIG. 1 is a cross-sectional perspective view schematically illustrating the structure of the combustion apparatus 1 of the present invention, and FIG. 3 is a schematic cross-sectional view of the combustion apparatus 1 of the present invention. In the following description, the vertical relationship is based on the posture in which the combustion apparatus 1 is placed vertically and a flame is generated on the upper side. The expressions on the upstream side and the downstream side are based on the flow of air or fuel gas. The width direction is a direction (in the direction of arrow W in the drawing) corresponding to the left-right direction with the largest area of the combustion device as the front.

  The combustion apparatus 1 is used in parallel in a case (not shown) or used alone. The combustion apparatus 1 of this embodiment includes a premixing member 2, a flame hole member 3, and two air flow path members 5. Among these, at least the flame hole member 3 and the air flow path member 5 are made of a material that can be energized.

  The premixing member 2 that is a constituent member of the combustion apparatus 1 is a member that performs a function of premixing the fuel gas 42 and the primary air 14 therein. The premixing member 2 includes an introduction portion 2a for introducing the primary air 14 and the fuel gas 42, a mixing portion 7 having a curved path, and an opening row portion 10 in which openings 8 are provided in a row. The opening row portion 10 is a portion in which a cavity having a substantially square cross section extends long and linearly.

  The air flow path member 5 is a member having a thin wall shape. The air flow path member 5 has a front surface 11 and a back surface 12 made of a thin plate, and the front surface 11 and the back surface 12 are joined with a slight gap, and three sides except for the lower surface side are joined. A gap serving as an air flow path 13 is provided. A top portion 9 (bending portion) extending in a ridge shape in the direction of the arrow W is formed at the tip portion of the air flow path member 5. On the other hand, on the base end side of the air flow path member 5, the space between the front surface 11 and the back surface 12 is opened, and an air introduction opening 15 for introducing the upstream secondary air 28 and the secondary air 67 is formed.

  Most of the plates of the front surface 11 and the back surface 12 of the air flow path member 5 are arranged in parallel, but only the front end portion is bent into a mountain shape, and inclined surfaces 16 and 17 are formed on the front surface side and the back surface side. Has been. A tip opening 20 is provided in the inclined surfaces 16 and 17. A tip end opening 21 is also provided at the most distal portion (ridge line portion) of the top portion 9. The tip openings 20 and 21 are provided for supplying secondary air 67 (downstream secondary air) to the secondary flame 68.

  Further, as shown in FIG. 1, the front surface 11 and the rear surface 12 of the air flow path member 5 are formed so that the front-side air flow path 13 is narrower than the base end side, and the base end of the first combustion section 46 is formed. An inclined surface 22 forming a step is provided at a portion corresponding to the portion. The inclined surface 22 is provided with an air discharge opening 23 for the combustion part. The air discharge opening 23 for the combustion section supplies the upstream secondary air 28 to the primary flame 24 (described later) of the first combustion section 46 and burns a part of the primary flame 24 to form a part in the first combustion section 46. A secondary flame 68 (described later) is generated.

  An air discharge opening (upstream air discharge opening) 48 is also provided at a position of the air flow path member 5 facing the flame hole member 3. The air discharge opening (upstream air discharge opening) 48 supplies the air to the side surface portion of the flame hole member 3 for flame holding.

  The flame hole member 3 includes a main body member 25 and a decompression wall 26. The main body member 25 of the flame hole member 3 has a top surface 30 that functions as a flame hole and two side wall portions 31 and 32. Further, the left and right sides of the flame hole member 3 are closed, and only the surface located on the lower side of the drawing is opened. The top surface 30 of the flame hole member 3 has a long shape and is elongated. On the top surface 30, slits to be the flame holes 33 are regularly arranged. The flame hole 33 functions as a “center opening”. A bulging portion 34 bulging outward (in the thickness direction) is provided at an intermediate portion between the side wall portions 31 and 32. The bulging portion 34 is provided over the entire width (in the direction of arrow W) of the flame hole member 3.

  As shown in FIG. 1, the open end sides of the side walls 31 and 32 are folded back twice to form a fitting concave groove 38 on the outside. The bottom wall 36 of the fitting groove 38 is perpendicular to the side walls 31 and 32, and the outer wall 37 of the fitting groove 38 is parallel to the side walls 31 and 32. The outer wall 37 is disposed in the air introduction opening 15, and the lower end of the air flow path member 5 is in contact with the outer wall 37 and the bottom wall 36, and is formed between the side wall portion 31 of the flame hole member 3 and the air flow path member 5. The gap 40 and the air flow path 13 communicate with each other through the air discharge opening 48. Further, the gap 40 is blocked by the bottom wall 36 from the external environment on the upstream side (lower side as viewed in FIG. 1).

  The lower portion (upstream side) of the pressure reducing wall 26 is fixed to the side wall portions 31 and 32 of the main body member 25, and a gap 29 is formed between the side wall portions 31 and 32 of the main body member 25. The upper part (downstream side) of the air gap 29 is open. This opening functions as the side opening 27. An opening 35 is provided in a portion of the side wall portions 31 and 32 of the main body member 25 facing the decompression wall 26, and the inner surface of the main body member 25 and the gap 29 communicate with each other through the opening 35.

  The side wall portions 31 and 32 and the opening row portion 10 are partially in contact with each other by an uneven shape (not shown), and both are integrated. Therefore, there is a gap between them. The cross section of FIG. 1 illustrates a cross section at a portion where the side wall portions 31 and 32 and the opening row portion 10 are separated.

  About the site | part corresponded to the bulging part 34 of the side wall parts 31 and 32, it is separated from the opening row | line | column part 10 included. The portion of the bulging portion 34 is at a position facing the row portion of the opening 8 of the opening row portion 10. Therefore, the outside of the opening 8 of the opening row portion 10 is separated from the side wall portions 31 and 32, and there is a wider space (mixing space) 39 than others. This space communicates over a portion corresponding to all the openings 8.

  There is a relatively large space 47 between the side wall portions 31 and 32 and between the top portion of the opening row portion 10 and the top surface 30 portion of the flame hole member 3. In the present embodiment, the flame hole upstream flow path is formed by the mixing space 39 and the space 47 on the downstream side of the opening row portion 10. An air introduction part 19 is formed between the premixing member 2 and the flame hole member 3. Air 43 (1.5th order air) is supplied to the air introduction unit 19 by the blower 41. The air 43 introduced from the air introduction unit 19 is mixed with the air-fuel mixture (primary air 14 and fuel gas 42) supplied from the opening 8 in the mixing space 39 and flows to the space 47 on the downstream side. As will be described in detail later, when the amount of air 43 introduced from the air introduction portion 19 decreases, the combustion speed of the primary flame 24 becomes slow and the combustion deteriorates. The present invention detects this deterioration of combustion.

  The top surface 30 of the flame hole member 3 is in a position buried between the air flow path members 5. Therefore, the space on the tip side of the top surface 30 of the flame hole member 3 is partitioned by the walls of the two air flow path members 5. A space surrounded by the top surface 30 of the flame hole member 3 and the two air flow path members 5 functions as the first combustion portion 46.

  Here, the primary flame 24 is that the fuel gas 42 and the primary air 14 are mixed in the premixing member 2 to generate a rich mixture, and the rich mixture flows out from the opening 8 into the space 47, In the space 47, the air is mixed with the air introduced from the air introduction part 19 (1.5th order air) and diluted, and further on the top surface 30 of the flame hole member 3, the upstream secondary air 28 from the combustion part air discharge opening 28. Is a flame that burns in an oxygen-deficient state. Further, the downstream secondary air 67 is supplied to the primary flame 24 from the front end openings 20 and 21 of the top portion 9 of the air flow path member 5, the air shortage is eliminated, and the secondary flame 68 is completely burned to generate the secondary flame 68. The

  In the combustion apparatus 1 described above, the first probe 65 (first conductive member) and the second probe 66 (second conductive member) are installed. That is, in the first combustion part 46 sandwiched between the two air flow path members 5 that are opposed to each other on the flame hole member 3, and in the primary flame 24 (primary combustion flame) generated at the time of combustion. At the position, the first probe 65 is disposed along the longitudinal direction (arrow W direction) of the combustion apparatus 1, and the second probe 66 is disposed in the vicinity of the tip portion of the air flow path member 5. The first probe 65 and the second probe 66 are fixed to a wall on the near side or the other side of the paper (not shown) that partitions the first combustion section 46.

  Since flame ions are present in the flame, the flame is electrically conductive. The 1st probe 65 and the 2nd probe 66 detect the conductive state by the ionic component in a flame.

  The first probe 65 is disposed in the primary flame 24. Here, the first probe 65 passes through the high-temperature flame surface of the primary flame 24, and the tip portion is disposed inside the primary flame 24. The second probe 66 is disposed at a position where the secondary air 67 supplied (injected) from the tip end opening 21 (secondary air supply port) hits (that is, in the vicinity of the tip end opening 21), and the secondary probe 66 It is cooled by air 67.

  As shown in FIG. 1, the lower end of the air flow path member 5 of the combustion apparatus 1 and the fitting concave groove 38 and the outer wall 37 of the flame hole member 3 are in contact with each other, so that the air flow path member 5 and the flame hole member 3 is connected to be energized. As shown in FIG. 3, when one pole of a common power source 50 (details will be described later) is connected to the air flow path member 5, the air flow path member 5 and the flame hole member 3 have no resistance, and so on. It becomes a potential.

  As shown in FIG. 3, the combustion device 1 (the air flow path member 5, the flame hole member 3), the first probe 65, and the common power source 50 (alternating current) are connected by electric wires, and when the primary flame 24 is generated. The flame ions are interposed between the top portion 30 of the flame hole member 3 and the first probe 65 to form the first AC circuit 55. That is, the first AC circuit 55 includes the first probe 65, the control device 69, the common power supply 50, the combustion device 1 (the air flow path member 5, the flame hole member 3), and the primary flame 24.

  Similarly, in the combustion apparatus 1, the second probe 66, and the common power supply 50, when the secondary flame 68 is generated, flame ions are interposed between the air flow path member 5 and the second probe 66, thereby forming the second AC circuit 56. Is done. That is, the second AC circuit 56 includes a second probe 66, a control device 69, a common power supply 50, a combustion device 1 (air flow path member 5), and a secondary flame 68.

  The controller 69 connected to the first AC circuit 55 and the second AC circuit 56 includes a first current value (signal) of the first current flowing through the first AC circuit 55 and a second current flowing through the second AC circuit 56. The second current value (signal) is input, and the control device 69 performs calculations, comparisons, determinations, and the like, which will be described later, and further the amount of air blown by the blower 41 and the fuel gas so as to keep the combustion of the combustion device 1 normal. The amount of fuel gas supplied is adjusted by adjusting the opening of the supply valve 59 and the like.

Hereinafter, control by the control device 69 will be described.
FIG. 2 is a control system diagram of the combustion apparatus 1 embodying the present invention.
As shown in FIG. 2, the first current value flowing through the first probe 65 (first AC circuit) and the second current value flowing through the second probe 66 (second AC circuit) are input to the control device 69. The control device 69 controls the blower 41 (supply air amount), the fuel gas supply valve 59 (fuel gas supply amount), and the fuel gas proportional valve 18 (fuel gas supply amount) as necessary.

  By the way, the common power source 50 converts electricity obtained from a commercial power source or a generator by a converter (not shown) into an alternating current having a voltage of 50 to 200 V and a frequency of 10 kHz or more, for example, and the first alternating circuit 55 and the second alternating current. Provided to circuit 56. If such high-frequency alternating current is used, an ion wind is not generated so that the flame ions in the primary flame 24 and the secondary flame 68 are biased to a specific place in the flame, and the shape of the flame is not destroyed. . The frequency is particularly preferably set to 50 kHz or more.

  As shown in FIG. 2, the control device 69 has a CPU 74 that functions as a calculation unit, a comparison unit, and a determination unit, and a memory 76 that can temporarily store preset values and detected signals. And. A first current and a second current are applied to the control device 69 from the first probe 65 and the second probe 66, and the first current and the second current are respectively a first current value I and a second current in the control device 69. Based on these detection signal values (first current value I, second current value II), the control device 69 converts the current value II into the blower 41 (FIG. 1), the fuel gas supply valve 59 (FIG. 1), and A command signal can be transmitted to the fuel gas proportional valve 18. At the start of operation of the combustion apparatus 1, the control device 69 transmits a command signal to the igniter 4 to ignite the fuel gas (air mixture) at an appropriate timing.

  The primary flame 24 has an insufficient amount of air with respect to the amount of fuel gas, and a large amount of hydrocarbon-based flame ions are present as a combustion atmosphere. Therefore, many flame ions are contained in the primary flame 24 during normal combustion, and the first current (first current value I) detected by the first probe 65 is large.

  The secondary flame 68 is supplied with a large amount of secondary air 67 and burns in a lean state, so the concentration of flame ions is relatively low. Therefore, the flame ion concentration in the secondary flame 68 during normal combustion is low, and the second current (second current value II) detected by the second probe 66 is small.

  Therefore, the control device 69 (CPU 74) of FIG. 2 performs calculations, comparisons, and determinations as in the first and second embodiments to determine the combustion state of the combustion device 1, and normalizes if the combustion is abnormal. .

(Example 1)
As described above, the first current value (signal value) detected by the primary flame 24 is “I”, and the second current value (signal value) detected by the secondary flame 68 is “II”. The sum “I + II” of these individual current values “I” and “II” is expressed as “Σ” (sigma). Further, the difference “II−I” between the second current value II and the first current value I is expressed as “Δ” (delta). Further, a value obtained by dividing “Δ” by “Σ” and “Δ / Σ” is defined as “R” (proportional value).

  The current values “I” and “II” differ depending on the type of fuel gas and the amount of combustion (within the range of the town down ratio). However, in the proportional value “R” obtained by calculating “Δ / Σ”, these values are The influence can be eliminated. Even if the voltage or frequency of the common power supply 50 fluctuates, the calculated proportional value “R” can cancel the fluctuation and eliminate the influence of the fluctuation. The proportional value “R” will be described in detail later.

  The range of the proportional value “R” at the time of normal combustion of the combustion device 1 is obtained by conducting an experiment in advance, and the proportional value “R” obtained by this experiment is stored in the memory 76 of the control device 69. . Then, during combustion of the combustion apparatus 1, the CPU 74 calculates a proportional value “R”, and further determines whether or not the calculated proportional value “R” is within a normal range stored in the memory 76.

  If the amount of supplied air is abnormally reduced, the combustion speed of the primary flame 24 decreases, the flame spreads downstream, eventually reaches the area of the secondary flame 68, and the air (oxygen) in the area of the secondary flame 68 Of the secondary flame 68 causes incomplete combustion, and the combustion gas of the secondary flame 68 contains a large amount of flame ions generated from hydrocarbons (HC), which are unburned components of the fuel gas. To be included.

  As a result, the increase in the second current value “II” due to the incomplete combustion of the secondary flame 68 is remarkable. On the other hand, in the primary flame 24, the flame ion concentration tends to increase due to air shortage. Since the temperature decreases, the flame ion concentration decreases, and the first current value “I” detected by the primary flame 24 becomes smaller. Therefore, as a result of “Δ” changing from minus to plus, the proportional value “R” also changes from minus to plus, deviating from a normal value within a predetermined range stored in the memory 76 of the control device 69, and the CPU 74 performs combustion. It is determined that the combustion of the device 1 is abnormal due to air shortage, and for example, the amount of air blown from the blower 41 is increased or the opening degree of either the fuel gas supply valve 59 or the fuel gas proportional valve 18 is decreased. Command signals are sent to the blower 41, the fuel gas supply valve 59, and the fuel gas proportional valve 18. As a result, the air-fuel ratio becomes appropriate, abnormal combustion due to an air shortage condition is eliminated, and the proportional value “R” becomes an appropriate value.

  Here, “Σ” in the denominator of the calculation formula for calculating the proportional value “R” was the current value “I + II”, but the current value “I” or “II” should be used instead of “Σ”. You can also. It is particularly preferable to adopt the current value “I” instead of “Σ”. That is, the current value “I” is proportional to the ion concentration in the primary flame 24. Compared with the ion concentration in the secondary flame 68, the ion concentration in the primary flame 24 more accurately reflects the difference in the fuel type and the change in the amount of combustion. Then, by taking the ratio using the current value “I”, the influence of the difference in the type of fuel and the amount of combustion can be canceled considerably. This situation will be described with reference to FIG.

  FIG. 6 is a graph showing the results of an experiment conducted by the applicant of the present application, and the above event is reflected in the graph of FIG. FIG. 6A is a graph showing the relationship between the unburned component concentration of the current value “I” on the primary flame 24 side and the current value “II” on the secondary flame 68 side, and FIG. FIG. 6C is a graph showing the relationship between the proportional value “R” of both and the unburned fuel component concentration when propane gas and city gas are used as the fuel gas. FIG. It is a graph which shows the relationship between proportional value "R" and unburned fuel component density | concentration in the case where it is large and small.

  As shown in FIG. 6A, the current value “I” is proportional to the unburned fuel component concentration, and the current value “I” is more related to the unburned fuel component concentration than the current value “II”. Is clear. Further, as shown in FIG. 6B, even if the gas type (propane fuel gas, city gas) is different, the relationship between the proportional value “R” and the unburned fuel component concentration is hardly changed. Further, as shown in FIG. 6C, the proportional value “R” hardly changes even if the voltage of the common power supply 50 fluctuates.

  In the first embodiment, “R = Δ / Σ” is calculated, and when the proportional value “R” increases, it is detected that there is a tendency of abnormal combustion due to air (oxygen) shortage. R1 = Σ / Δ ”and the proportional value“ R1 ”may be decreased to detect abnormal combustion due to air shortage.

  In the first embodiment, the proportional value “R” (or “R1”) is calculated. However, when the proportional value “R” (or “R1”) is calculated, a constant may be multiplied as necessary. You may add. That is, the proportional value “R” may be calculated as “R = ε · Δ / Σ + κ” (“R1 = ε1 · Σ / Δ + κ1”). Here, ε, κ, ε1, and κ1 are arbitrary numbers.

  Here, we will mention the results of experiments conducted by the applicant. FIG. 5 is a graph showing the relationship between the detected current value and the unburned component concentration of the fuel gas when the present invention is implemented. In all of curve A, curve B, and curve C, the current value increases abruptly when the unburned component concentration slightly increases from near zero, and the subsequent current value increases slowly or hardly changes. . That is, in the atmosphere of the secondary flame 68, since the unburned component concentration is low, if the normal combustion state, the detected second current value “II” is low, but even if the unburned component concentration is slightly improved, The second current value “II” suddenly increases. Curve A and curve B are graphs when the same fuel gas is burned, but curve A is a graph when the combustion temperature is higher than curve B. In other words, since the amount of combustion in the case of curve A is larger than that in the case of curve B, the heat loss of the combustor is small, and the combustion temperature rises. From the graph of FIG. 5, it can be seen that the higher the combustion temperature, the easier the molecules to ionize and the higher the detected current value.

(Example 2)
FIG. 4 is a schematic cross-sectional view of a combustion apparatus different from the first embodiment of FIG. 3 in which the present invention is implemented. As shown in FIG. 4, in the second embodiment, the current flowing through the first AC circuit 55 is converted into the first current value I (signal value) by the converter 52, and the first current value I is A / D converted. Is transmitted to the control device 69. Similarly, the current flowing through the second AC circuit 56 is converted into a second current value II (signal value) by the converter 53, and the second current value II is A / D converted and transmitted to the control device 69. .

  The A / D conversion value of the first current value I of the primary flame 24 is “D (I)”, and the A / D conversion value of the second current value II of the secondary flame 68 is “D (II)”. These individual converted values “D (I)”, “D (II)”, or the sum of these converted values “D (I) + D (II)” are expressed as “ΣD” (sigma). Also, “D (II) −D (I)”, which is the difference between the converted values “D (I)” and “D (II)”, is expressed as “ΔD” (delta). Further, a value obtained by dividing “ΔD” by “ΣD” and “ΔD / ΣD” is defined as “R2” (proportional value).

  The conversion values “D (I)” and “D (II)” vary depending on the type of fuel gas and the amount of combustion (within the range of the town down ratio), but the proportional value “ΔD / ΣD” is calculated. In “R2”, these effects can be eliminated. Even if the frequency and voltage of the common power supply 50 may fluctuate, the proportional value “R2” can cancel out the fluctuations and eliminate the influence of the fluctuations.

  The memory 76 of the control device 69 stores a range of the proportional value “R2” during normal combustion of the combustion device 1 in advance. When the combustion apparatus 1 burns, the CPU 74 calculates a proportional value “R2”, and further determines whether or not the calculated proportional value “R2” is within a range of normal proportional values stored in the memory 76. judge.

  Here, the denominator “ΣD” for calculating the proportional value “R2” may be any of the converted values “D (I)”, “D (II)”, and “D (I) + D (II)”. However, it is preferable to adopt the conversion value “D (I)” or “D (I) + D (II)”. That is, the conversion value “D (I)” is proportional to the ion concentration in the primary flame. Compared with the ion concentration in the secondary flame, the ion concentration in the primary flame more accurately reflects the difference in the fuel type and the change in the combustion amount. In addition, since the graph of the experimental result of Example 2 becomes a graph similar to the graph of FIG. 6 of Example 1, description is abbreviate | omitted.

  When the control device 69 determines that the combustion is abnormal and takes the above measures and then normalizes the combustion, the control device 69 sets the proportional value “R2” in advance and stores it in the memory 76. The opening degree of the blower 41, the fuel gas supply valve 59 or the fuel gas proportional valve 18 is adjusted so as not to deviate from the predetermined range. Then, when the control device 69 determines that the combustion is abnormal, the user can be alerted by blinking an alarm lamp or the like so that proper maintenance can be performed.

  Similarly to the proportional value “R” in the first embodiment, the proportional value “R2” calculated in the second embodiment may be multiplied by a constant as necessary. That is, instead of the proportional value “R2”, the proportional value “R3” may be calculated as “R3 = ε · ΔD / ΣD + κ”. Here, ε and κ are arbitrary numbers.

It is a fragmentary perspective view of the combustion apparatus which implements this invention. It is a control system diagram of the combustion apparatus which implemented this invention. 1 is a schematic sectional view of a combustion apparatus embodying the present invention. FIG. 4 is a schematic cross-sectional view of a combustion apparatus different from FIG. 3 embodying the present invention. It is a graph which shows the relationship between the detected electric current value and unburned component density | concentration for every fuel gas to be used. (A) is a graph showing the relationship between the unburned component concentration of the current value “I” on the primary flame side and the current value “II” on the secondary flame side. (B) is a graph showing the relationship between the proportional value “R” between the fuel gas and the unburned fuel component concentration when propane gas and city gas are employed. (C) is a graph showing the relationship between the proportional value “R” and the unburned fuel component concentration when the voltage of the common power source is large and small.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Combustion device 2 Premix member 3 Flame hole member 5 Air flow path member 13 Air flow path 14 Primary air 15 Air introduction opening 18 Fuel gas proportional valve 20, 21 Front-end | tip opening 24 Primary flame 41 Blower 42 Fuel gas 46 First combustion 50 AC power supply 59 Fuel gas supply valve 65 First probe (first conducting member)
66 Second probe (second conducting member)
67 Secondary air 68 Secondary flame 69 Controller 74 CPU
76 Memory I First current value
II Second current value D (I) I A / D conversion value (first A / D conversion value)
A / D conversion value of D (II) II (second A / D conversion value)
R, R1, R2, R3 Proportional value ΣI + II current value ΣD D (I) and D (II) sum Δ II and I difference between current values ΔD D (I) and D (II)

Claims (4)

In a combustion apparatus in which an oxygen-deficient mixture formed by mixing primary air and fuel gas undergoes primary combustion, and further receives secondary air supply to perform secondary combustion.
The first conductive member is disposed in the primary combustion flame, the second conductive member is disposed in the secondary combustion flame, and a voltage is further applied to the primary combustion flame and the secondary combustion flame. And detecting a first current value flowing in the primary combustion flame and a second current value flowing in the secondary combustion flame,
The combustion state is calculated by a calculation formula including the sum of the detected first current value and the second current value, the first current value, the second current value, and the ratio of the difference between the second current value and the first current value. The combustion apparatus characterized by determining. In a combustion apparatus in which an oxygen-deficient mixture formed by mixing primary air and fuel gas undergoes primary combustion, and further receives secondary air supply to perform secondary combustion.
The first conductive member is disposed in the primary combustion flame, the second conductive member is disposed in the secondary combustion flame, and a voltage is further applied to the primary combustion flame and the secondary combustion flame. And detecting a first current value flowing in the primary combustion flame and a second current value flowing in the secondary combustion flame,
A sum of the first A / D conversion value of the first current value and the second A / D conversion value of the second current value, the first A / D conversion value, the second A / D conversion value, and the first A combustion apparatus for determining a combustion state by a calculation formula including a ratio of a difference between a second A / D conversion value and a first A / D conversion value. In a combustion apparatus in which an oxygen-deficient mixture formed by mixing primary air and fuel gas undergoes primary combustion, and further receives secondary air supply to perform secondary combustion.
The first conductive member is disposed in the primary combustion flame, the second conductive member is disposed in the secondary combustion flame, and a voltage is further applied to the primary combustion flame and the secondary combustion flame. And detecting a first current value flowing in the primary combustion flame and a second current value flowing in the secondary combustion flame,
The sum of the first current value detected by the first conductive member and the second current value detected by the second conductive member, the first current value, the second current value, the second current value and the first current value A combustion apparatus that controls at least one of a supply air amount and a supply fuel gas amount according to a difference ratio of one current value. In a combustion apparatus in which an oxygen-deficient mixture formed by mixing primary air and fuel gas undergoes primary combustion, and further receives secondary air supply to perform secondary combustion.
The first conductive member is disposed in the primary combustion flame, the second conductive member is disposed in the secondary combustion flame, and a voltage is further applied to the primary combustion flame and the secondary combustion flame. And detecting a first current value flowing in the primary combustion flame and a second current value flowing in the secondary combustion flame,
The sum of the first A / D conversion value of the first current value detected by the first conductive member and the second A / D conversion value of the second current value detected by the second conductive member, first A / Of the supplied air amount and the supplied fuel gas amount, depending on the D conversion value, the second A / D conversion value, and the ratio of the difference between the second A / D conversion value and the first A / D conversion value. A combustion apparatus that controls at least one of the above.

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