Gas combustion equipment

Abstract

To grasp a combustion state in a real-time manner with excessive air being taken into consideration and to maintain the excellent combustion state while attempting the simplification of a structure and the cost reduction in a gas combustion apparatus.SOLUTION: A gas combustion apparatus includes: a gas burner 20; a flame rod 25 that is exposed to the flame of the gas burner to generate a flame current; and a control unit 110 that controls combustion. When the number of combustion flames of the gas burner is n and the number of complete combustion flames thereof is N, a gas unit heat generation amount of a fuel gas is H and a gas necessary air rate is m, a gas amount is Qg, an air amount is Qa, a constant proportional to the number of flames contributing to the flame current is k1, and a constant contributing to an applied voltage of the flame rod and a resistance value thereof is k2, the control unit controls the gas amount and / or the air amount supplied to the gas burner on the basis of a calculated flame current value If calculated from a combustion characteristic formula If=[k1ln(HQg / n)+k2]exp[-(nQa / NmQg-1)2], and an actually measured flame current value of the flame rod.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a gas combustion device that mixes fuel gas with air and burns the mixture, and in particular to a flame This invention relates to a gas combustion device that provides the required output thermal power while controlling combustion using a flame sensor such as a rod. [Background technology]

[0002] A conventional method for detecting the combustion state of a burner in a gas combustion apparatus is to use a flame current of a flame rod that utilizes the conductive effect of a flame. Therefore, in a combustion device equipped with a multi-stage switching burner that can switch the combustion mode in multiple stages, when detecting the combustion state using one flame rod, the flame current detected will be in a combustion state that contains a lot of air due to the generation of excess air from the unburned burner, and the combustion state cannot be detected accurately. Therefore, using a plurality of flame rods or other combustion sensors leads to a complicated structure, high costs, and the like.

[0003] Incidentally, a known conventional gas combustion device is a water heater that includes a combustion section that has a first burner section that is equipped with a flame rod that detects the combustion state of the flame generated by the burner and a second burner section that is not equipped with a flame rod, a combustion control section that monitors the combustion mode of the combustion section that is set in response to a hot water supply request and changes the mode to the first combustion mode that burns the first burner section if the second combustion mode that does not burn the first burner section continues for a certain period of time, and a combustion adjustment control section that takes in information about the combustion state of the first burner section detected by the flame rod and performs combustion adjustment processing of the combustion section (see, for example, Patent Document 1).

[0004] This water heater employs a control method in which, if a combustion mode that cannot be detected by the flame rod continues for a certain period of time, it switches to a combustion mode that can be detected by the flame rod. Therefore, in a combustion mode that cannot be detected by the flame rod for a certain period of time, the combustion state cannot be detected in real time, and CO and NO X However, it is not possible to control combustion so as to achieve a favorable combustion state that can suppress emissions.

[0005] Another known gas combustion device is a gas-fired water heater that includes a gas proportional valve that controls the fuel gas supply pressure to the burner, a fan that supplies air at a volume corresponding to the rotational speed, a control means that sets a target gas pressure for generating a target amount of heat in the burner and a target rotational speed for supplying an air volume that achieves a predetermined air-fuel ratio, a fan control unit that controls the fan rotational speed according to the target rotational speed, and a rotational speed detector that detects the fan rotational speed (see, for example, Patent Document 2). In this water heater, the fuel gas supply pressure (gas volume) is determined taking into account the sensing delay of the rotational speed detector in order to maintain the air-fuel ratio during a transient period when the target rotational speed of the fan is changed.

[0006] In this way, in conventional gas combustion systems, the response of the air supply volume relative to the gas supply volume is slow during the transient state of air-fuel ratio control between air and fuel gas, so control must take into account the responsiveness of both, which makes the control complex. Furthermore, the dynamic characteristics of the fan and fan motor affect the system responsiveness. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Publication No. 2020-143862 [Patent Document 2] Japanese Patent Application Laid-Open No. 2014-122763 Summary of the Invention [Problem to be solved by the invention]

[0008] The present invention has been made in consideration of the above circumstances, and its purpose is to provide a gas combustion device that has a simplified structure, low cost, etc., can grasp the combustion state in real time taking into account excess air, can maintain a good combustion state, and has improved responsiveness to the amount of air to be supplied. [Means for solving the problem]

[0009] The gas combustion device of the present invention mixes fuel gas with air and burns it according to the output thermal power. At the same time, it is a multi-stage switching type that generates multiple capacities with different amounts of gas supplied depending on the size of the output heating power. a gas burner; and a flame rod that is exposed to the flame of the gas burner to generate a flame current; A gas amount adjusting valve that adjusts the amount of fuel gas for the gas burner, an air amount adjusting unit that adjusts the amount of air to be mixed with the fuel gas, and a gas amount adjusting valve and an air amount adjusting unit that controls the gas amount adjusting valve and the air amount adjusting unit. The control unit controls the combustion, and the control unit determines the number of combustion flames of the gas burner as n, the total number of combustion flames as N, the unit calorific value of the fuel gas as H, the required air ratio of the gas as m, and the amount of gas as Q g , the air volume Q a When the constant proportional to the number of flames contributing to the flame current is k1 and the constant contributing to the applied voltage and resistance value of the flame rod is k2, the following combustion characteristic equation is obtained: I f =[k1ln(HQ g / n)+k2]exp[-(nQ a / NmQ g -1) 2 ] The calculated frame current value I f and the amount of gas and / or air supplied to the gas burner is controlled based on the actually measured flame current value of the flame rod. and includes a storage unit that stores characteristic information calculated based on a combustion characteristic formula corresponding to a plurality of capacities, an output thermal power calculation unit that calculates an output thermal power, a capacity switching unit that determines whether to switch to a required capacity based on the output thermal power information of the output thermal power calculation unit, and a correction amount calculation unit that compares an actually measured flame current value with a calculated flame current value and calculates a correction amount based on the deviation, and controls the gas amount adjustment valve based on the output thermal power information, capacity number information of the capacity switching unit, and correction amount information of the correction amount calculation unit. It is composed of:

[0010] In the above-mentioned gas combustion device, the control unit may be configured to control the amount of gas and / or air to decrease or increase when the actual measured flame current value deviates from the calculated flame current value, so that the actual measured flame current value matches the calculated flame current value.

[0012] In the gas combustion apparatus, the characteristic information stored in the storage unit may include characteristic information indicating a relationship between the amount of fuel gas and the calculated flame current value.

[0015] In the gas combustion apparatus, the control unit may be configured to control the air amount adjustment unit based on the output thermal power information and the capacity number information.

[0016] In the above gas combustion device, the air amount adjustment unit may include a fan that is driven to rotate at a constant rotation speed to generate an air flow toward the gas burner, and an air amount adjustment valve that adjusts the amount of air supplied to the gas burner, and the control unit may include a target opening calculation unit that calculates a target opening of the air amount adjustment valve based on output firepower information and capacity number information from the capacity switching unit, and an opening control unit that controls the opening of the air amount adjustment valve based on the target opening information from the target opening calculation unit.

[0017] In the gas combustion apparatus, the control unit may be configured to drive the fan to rotate at a constant rotation speed set for each of a plurality of capacities.

[0018] In the gas combustion device , the control unit A configuration may be adopted that includes a target rotation speed calculation unit that calculates the target rotation speed of the fan based on output firepower information and capacity number information, and a rotation control unit that drives the fan to rotate at a constant rotation speed based on the target rotation speed information from the target rotation speed calculation unit.

[0019] In the gas combustion apparatus, the air amount adjustment valve may have a configuration including a drive source and a butterfly valve that is driven to open and close by the drive source.

[0020] In the gas combustion device, the drive source may be a stepping motor.

[0021] In the gas combustion apparatus, the fan may include a motor that generates a rotational driving force, and the motor may be an AC motor.

[0022] The gas combustion apparatus may have a configuration including a heat exchanger disposed adjacent to the gas burner. [Effects of the Invention]

[0023] The gas combustion device having the above configuration can simplify the structure, reduce costs, etc., while also being able to grasp the combustion state and maintain a good combustion state.It also improves the responsiveness of the amount of air to be supplied, making it possible to obtain the desired output thermal power. [Brief explanation of the drawings]

[0024] [Figure 1] 1 is a block diagram showing the configuration of a gas combustion apparatus according to a first embodiment of the present invention. [Figure 2] 1 is a partial view of a gas combustion apparatus according to a first embodiment. [Figure 3] 1 is a schematic diagram showing the combustion state (relationship between the number of combustion flames and the flame rod) according to the capacity (capacity 1 to capacity 4) of the multistage switching gas burner in the gas combustion device according to the first embodiment. FIG. [Figure 4] 2 is a block diagram showing the configuration of a control unit in the gas combustion device according to the first embodiment. FIG. [Figure 5] 3 is a graph showing the relationship between the valve opening degree and the amount of air in the air amount adjustment valve included in the gas combustion apparatus according to the first embodiment. [Figure 6] 1 is a graph showing the relationship between the air ratio λ and the flame current measured for each capacity (Capacity 1 to Capacity 4) in the gas combustion apparatus of the present invention. [Figure 7] 1 is a graph showing the relationship between the amount of fuel gas actually measured for each capacity (Capacity 1 to Capacity 4) and the flame current in the gas combustion device of the present invention. [Figure 8] 1 is a graph showing the relationship between the amount of fuel gas calculated for each capacity (Capacity 1 to Capacity 4) using a combustion characteristic equation and the flame current in the gas combustion device of the present invention. [Figure 9]10 is a graph showing the relationship between the deviation of the actually measured flame current value from the flame current value calculated based on the combustion characteristic equation and the amount of fuel gas in the gas combustion device of the present invention. [Figure 10] 3 is a flowchart showing the overall operation control in the control unit in the gas combustion apparatus of the present invention. [Figure 11] 3 is a flowchart showing combustion control in a control unit in the gas combustion apparatus of the present invention. [Figure 12] FIG. 6 is a block diagram showing the configuration of a control unit in a gas combustion apparatus according to a second embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0025] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings. As shown in Figures 1 and 2, the gas combustion apparatus of the first embodiment includes a housing 10, a gas burner 20, an igniter 24, a flame rod 25, a gas supply pipe 30, a gas volume control valve 40, gas switching valves 51, 52, and 53, an air volume control valve 60, a fan 70, a heat exchanger 80, a water supply pipe 90, a hot water supply pipe 100, and a control unit 110. Here, the gas combustion device is configured as a gas water heater. The air amount adjustment valve 60 and the fan 70 configure an air amount adjustment unit.

[0026] The housing 10 is formed from a heat-resistant metal plate or the like, and as shown in Figure 2, has an internal space 11 surrounding the gas burner 20 and the heat exchanger 80, an intake port 12 for drawing air into the internal space 11, and an exhaust port 13 for discharging combustion gas from the internal space 11.

[0027] As shown in Figures 2 and 3, the gas burner 20 has multiple gas nozzles, including multiple (four) first nozzles 21 that spray fuel gas supplied by the first branch supply pipe 32, multiple (two) second nozzles 22 that spray fuel gas supplied by the second branch supply pipe 33, and multiple (nine) third nozzles 23 that spray fuel gas supplied by the third branch supply pipe 34.

[0028] The first nozzle 21 functions as a burner 1 that ejects fuel gas supplied by opening the gas amount adjustment valve 40 and the gas switching valve 51. When the fuel gas ejected from the first nozzle 21 burns, the number of combustion flames is four. The second nozzle 22 functions as a burner 2 that ejects fuel gas supplied by opening the gas amount adjustment valve 40 and the gas switching valve 52. When the fuel gas ejected from the second nozzle 22 burns, the number of combustion flames is two. The third nozzle 23 functions as a burner 3 that ejects fuel gas supplied by opening the gas amount adjustment valve 40 and the gas switching valve 53. When the fuel gas ejected from the third nozzle 23 burns, the number of combustion flames is nine.

[0029] The gas burner 20 generates a plurality of capacities, namely, capacity 1, capacity 2, capacity 3, and capacity 4, which differ in the amount of fuel gas supplied depending on the magnitude of the output thermal power. At capacity 1, the gas amount adjustment valve 40 and the gas switching valve 51 are opened, so that only burner 1 burns, and burner 2 and burner 3 are supplied with only air, not fuel gas. At capacity 2, the gas amount adjustment valve 40 and the gas switching valves 51 and 52 are opened, so that burners 1 and 2 are combusted, and burner 3 is supplied with only air and no fuel gas. At capacity 3, the gas amount adjustment valve 40 and the gas switching valves 52 and 53 are opened, so that burners 2 and 3 are combusted, and no fuel gas is supplied to burner 1, and only air is supplied. At capacity 4, the gas amount adjustment valve 40 and the gas switching valves 51, 52, and 53 are opened, and burner 1, burner 2, and burner 3 are combusted. That is, in the combustion mode of capacity 1, the number of combustion flames n is 4, in the combustion mode of capacity 2, the number of combustion flames n is 6, in the combustion mode of capacity 3, the number of combustion flames n is 11, and in the combustion mode of capacity 4, the number of combustion flames n is 15. Therefore, when all of the fuel gas ejected from the first ejection port 21, the second ejection port 22, and the third ejection port 23 is combusted, the total number of combustible flames, ie, the total number N of combustion flames, is 15.

[0030] The igniter 24 ignites the fuel gas and operates based on a command from the control unit 110 . 2 and 3, the flame rod 25 is disposed so as to be exposed to the flame of the gas burner 20, and monitors whether or not a flame exists when a voltage is applied between the flame rod 25 and the gas burner 20. In other words, when exposed to the flame, a flame current is generated. Information on the flame current output from the flame rod 25 is input to the control unit 110.

[0031] Here, as shown in FIG. 3, the flame rod 25 is arranged so that in the combustion mode of capacity 1 it is exposed to one flame of burner 1, in the combustion mode of capacity 2 it is exposed to one flame of burner 1 and two flames of burner 2, in the combustion mode of capacity 3 it is exposed to two flames of burner 2, and in the combustion mode of capacity 4 it is exposed to one flame of burner 1 and two flames of burner 2. That is, the flame rod 25 is not arranged to be exposed to the number of flames corresponding to the magnitude of the output thermal power. a is the calculated flame current value I calculated by the combustion characteristic formula (2) described below. f The correction process is performed based on the above.

[0032] As shown in FIGS. 1 and 2, the gas supply pipe 30 includes an upstream pipe 31, a first branch supply pipe 32, a second branch supply pipe 33, and a third branch supply pipe . The upstream pipe 31 is located upstream of the first branch supply pipe 32, the second branch supply pipe 33, and the third branch supply pipe , and a gas amount adjustment valve is disposed midway therethrough. The first branch supply pipe 32 communicates with the first nozzle 21 (burner 1) of the gas burner 20 via a gas switching valve 51. The second branch supply pipe 33 communicates with the second nozzle 22 (burner 2) of the gas burner 20 via a gas switching valve 52. The third branch supply pipe 34 communicates with the third nozzle 23 (burner 3) of the gas burner 20 via a gas switching valve 53.

[0033] As shown in FIG. 1, the gas amount control valve 40 is a proportional solenoid valve that is arranged in the gas supply pipe 30 in the middle of the upstream pipe 31, and the current passing therethrough is appropriately controlled by PWM control. The opening degree is adjusted between a position where the passage through which the fuel gas passes and a position where it is fully open, thereby adjusting the amount of fuel gas supplied to the gas burner 20. That is, the gas amount regulating valve 40 has its opening controlled by the current flowing therethrough based on a command from the control unit 110 in order to maintain a predetermined air ratio λ for the required output thermal power, and regulates the amount of fuel gas supplied to the gas burner 20. Here, the air ratio λ is the ratio (mass ratio) of the amount of air actually supplied to the theoretical amount of air required for complete combustion of the fuel gas.

[0034] The gas switching valve 51 is an electromagnetic valve that is arranged midway along the first branch supply pipe 32 in the gas supply pipe 30 that supplies fuel gas, and is driven to open and close so as to fully close or fully open the passage through which the fuel gas passes, thereby adjusting the amount of fuel gas supplied to the first nozzle 21 of the gas burner 20. The gas switching valve 52 is an electromagnetic valve that is arranged midway along the second branch supply pipe 33 in the gas supply pipe 30 that supplies fuel gas, and is driven to open and close so as to fully close or fully open the passage through which the fuel gas passes, thereby adjusting the amount of fuel gas supplied to the second nozzle 22 of the gas burner 20. The gas switching valve 53 is an electromagnetic valve that is arranged midway along the third branch supply pipe 34 in the gas supply pipe 30 that supplies fuel gas, and is driven to open and close so as to fully close or fully open the passage through which the fuel gas passes, thereby adjusting the amount of fuel gas supplied to the third nozzle 23 of the gas burner 20. That is, the gas switching valves 51 , 52 , 53 are controlled to open and close based on commands from the control unit 110 in accordance with the required output thermal power, and adjust the amount of fuel gas supplied to the gas burner 20 .

[0035] As shown in Figure 2, the air volume adjustment valve 60 is arranged at the intake port 12 of the housing 10 and adjusts the amount of air flowing into the housing 10, and is equipped with a butterfly valve 61 and a drive source 62 that drives the butterfly valve 61 to open and close. When the butterfly valve 61 is in a stopped state, it is set to a rest position where the air passage is opened to a predetermined opening, and when it is activated, it is driven to open and close within a range from the rest position through the fire extinguishing opening and ignition opening to the fully open position. Note that the rest position may be the same as the fire extinguishing position. The drive source 62 is a stepping motor that is driven by applying a pulse voltage, and is controlled to be driven based on commands from the control unit 110 . As shown in FIG. 5, the air amount adjustment valve 60 has a characteristic that shows a proportional relationship in which the amount of air passing through increases at a constant rate relative to the opening of the butterfly valve 61, and is controlled so that the opening increases as the output thermal power increases. That is, the air amount adjusting valve 60 is controlled to open and close based on commands from the control unit 110 to adjust the amount of air supplied to the gas burner 20 in order to maintain a predetermined air ratio λ for the required output thermal power.

[0036] As shown in FIG. 2, the fan 70 is disposed near the exhaust port 13 of the housing 10 to blow out the air or combustion gas inside the housing 10, and is equipped with a rotor 71 including multiple blades and a motor 72 that drives the rotor 71 to rotate. The motor 72 is an AC motor that maintains a constant rotation speed according to the frequency. The motor 72 also includes a sensor that detects the number of rotations, and the information detected by the sensor is input to the control unit 110. That is, the fan 70 is positioned to generate an air flow from the intake port 12 toward the gas burner 20, and is driven to rotate at a constant rotation speed based on a command from the control unit 110 to maintain a predetermined air ratio λ for the required output thermal power.

[0037] As shown in Figure 2, the heat exchanger 80 is positioned immediately above and adjacent to the gas burner 20 within the housing 10, and serves to transfer the heat generated by the gas burner 20 to the water supply (room temperature water) supplied through the water supply piping 90. That is, the heat exchanger 80 heats normal temperature water such as tap water supplied from the water supply pipe 90 and supplies the water to the hot water supply pipe 100 as hot water.

[0038] As shown in FIG. 1, the water supply pipe 90 is connected to the upstream side of the heat exchanger 80 and carries room temperature water such as tap water, and is provided with a water flow rate sensor 91 and an inlet temperature sensor 92 along the way. The water flow rate sensor 91 detects the flow rate of the water supply flowing through the water supply pipe 90. The detection information of the water flow rate sensor 91 is input to the control unit 110. The inlet temperature sensor 92 detects the temperature of the feedwater flowing through the feedwater pipe 90. The information detected by the inlet temperature sensor 92 is input to the control unit 110.

[0039] As shown in Figure 1, the hot water supply pipe 100 is connected downstream of the heat exchanger 80 and carries hot water heated by the heat exchanger 80, and is equipped with an outlet temperature sensor 101 and a hot water tap 102 along the way. The outlet temperature sensor 101 detects the temperature of the hot water flowing through the hot water supply pipe 100. The information detected by the outlet temperature sensor 101 is input to the control unit 110. The hot water tap 102 is an on-off valve that is operated by an operator.

[0040] The control unit 110 is configured as a controller that includes a processor, a display unit, a timer, a communication unit that communicates with an external remote controller 110a, electronic components and electronic circuits that form an input / output interface, and the like. The timer measures the elapsed time in the control sequence. The external remote controller 110a is connected to the control unit 110 by wire or wirelessly, and includes an operation section that allows an operator to set the selected temperature of hot water, a display section that displays the combustion state and warnings, and the like.

[0041] As shown in FIG. 4, the control unit 110 includes a target thermal power calculation unit 111, an outlet temperature F / B control unit 112, an output thermal power calculation unit 113, a capacity switching unit 114, a target opening calculation unit 115 and opening control unit 116 for the air amount control valve 60, a target current calculation unit 117 and current control unit 118 for the gas amount control valve 40, a rotation control unit 119 for the fan 70, a memory unit 120 that stores various control information, etc., and a correction amount calculation unit 121.

[0042] The target thermal power calculation unit 111 calculates the detection signal (water flow rate Q w ), the detection signal of the inlet temperature sensor 92 (T in ), and the information on the set temperature (T) set by the external remote controller 110a, the target heating power is calculated as a feedforward amount. Here, the target thermal power is calculated using the following formula (1). Target firepower = water flow rate (Q w ) × (Set temperature (T) - Inlet temperature (T in )) / 25 (1)

[0043] The outlet temperature F / B control unit 112 receives the detection signal (T out ) and the information on the set temperature (T) set by the external remote controller 110a, the correction heating power is calculated as a feedback amount. The output thermal power calculation unit 113 calculates the output thermal power based on information on the target thermal power, which is the feedforward amount output by the target thermal power calculation unit 111, and the corrected thermal power, which is the feedback amount output by the outlet temperature F / B control unit 112.

[0044] The capacity switching unit 114 determines whether to switch to the required capacity based on the output thermal power information output by the output thermal power calculation unit 113, and issues a command signal to do so. Here, the above-mentioned capacity 1, capacity 2, capacity 3, and capacity 4 are set as a plurality of capacities with different amounts of gas supplied corresponding to the magnitude of the output thermal power. That is, at capacity 1, the capacity switching unit 114 issues a command signal to open only the gas switching valve 51, at capacity 2, it issues a command signal to open only the gas switching valves 51 and 52, at capacity 3, it issues a command signal to open only the gas switching valves 52 and 53, and at capacity 4, it issues a command signal to open the gas switching valves 51, 52, and 53. Furthermore, the capability switching unit 114 outputs capability numbers corresponding to capability 1, capability 2, capability 3, and capability 4, respectively, as capability number information.

[0045] The target opening calculation unit 115 calculates the target opening of the air amount adjustment valve 60 from map (table) information stored in the storage unit 120, based on the output thermal power information output by the output thermal power calculation unit 113 and the capacity number information output by the capacity switching unit 114. Here, the map information is information related to the opening that is set to supply the amount of air required to generate the amount of heat according to the capacity number while maintaining a predetermined air ratio λ. The opening control unit 116 applies a pulse voltage to the drive source 62 (stepping motor) of the air amount adjusting valve 60 based on the target opening information output by the target opening calculation unit 115, to drive the air amount adjusting valve 60 to the target opening.

[0046] Target current calculation unit 117 calculates a target current corresponding to the opening of gas amount regulating valve 40 based on the capacity number information output by capacity switching unit 114, the target opening information output by target opening calculation unit 115, map (table) information stored in storage unit 120, and correction amount information output by correction amount calculation unit 121. Here, the map information is information related to a current that is set to supply the amount of gas required to generate the amount of heat corresponding to the capacity number while maintaining a predetermined air ratio λ.

[0047] The current control unit 118 performs PWM control of the current flowing through the gas amount regulating valve 40 (proportional electromagnetic valve) based on the target current information output by the target current calculation unit 117 and feedback information of the actual current, thereby adjusting the amount of fuel gas supplied through the gas amount regulating valve 40.

[0048] The rotation control unit 119 drives the motor 72 of the fan 70 to rotate at a constant rotation speed based on information regarding the target rotation speed stored in advance and feedback information on the actual rotation speed, in response to a command signal issued from the processor based on the output signal of the water flow sensor 91.

[0049] The memory unit 120 stores programs for controlling the overall operation, controlling combustion, and monitoring the combustion state, map (table) information related to the combustion state, map information related to the amount of air and fuel gas required to maintain a predetermined air ratio λ (for example, λ1 at capacity 1, λ2 at capacity 2, λ3 at capacity 3, and λ4 at capacity 4), characteristic information based on the combustion characteristic equation (2), and other information, and is composed of memory elements such as ROM and RAM.

[0050] Here, the combustion characteristic formula (2) is an empirical formula derived by the inventor as a result of extensive research, and is expressed as follows: n is the number of combustion flames of the gas burner 20, N is the total number of combustion flames, and H (kw / Nm 3 ) and the required air rate of gas is m, and the gas amount is Q g (m 3 / h), and the air volume Q a (m 3 / h), the constant proportional to the number of flames contributing to the flame current is k1, and the constant contributing to the applied voltage and resistance value of the flame rod 25 is k2. The calculated flame current value I f (μA) is I f =[k1ln(HQ g / n)+k2]exp[-(nQ a / NmQ g -1) 2 ] (2) It can be expressed as: Here, the fuel gas used may be, for example, methane or propane. The combustion formula for methane is CH4 + 2O2 → CO2 + 2H2O, and the calorific value per unit gas, H, is 11.04kw / Nm 3 and the gas required air ratio m is 9.52 (2 / 0.21). The combustion formula for propane is C3H8 + 5O2 → 3CO2 + 4H2O, and the calorific value per unit gas, H, is 27.64kw / Nm 3 and the gas required air ratio m is 23.81 (5 / 0.21).

[0051] In deriving the combustion characteristic formula (2) above, combustion experiments were conducted in a gas combustion device for capacities 1 to 4. As a result, the relationship between the air ratio λ and the flame current was obtained as shown in Figure 6. Furthermore, the relationship between the gas amount and the flame current was obtained as shown in Figure 7. As can be seen from these results, the flame current value is approximately proportional to the combustion power (output firepower) and the number of flames in contact with the flame rod 25. In other words, even if the combustion power is large, as in capacity 3, if the number of flames in contact with the flame rod 25 is small, the flame current value will be small, and in a combustion state where the combustion power is large and current is transmitted between adjacent flames, as in capacity 4, the flame current value will be large.

[0052] Furthermore, when controlling combustion, an air ratio λ is selected in each combustion mode of Capacities 1 to 4 to provide an optimal combustion state in which CO and NOx emissions are reduced. In reality, not all of the air is used for combustion, so an excess amount of air is supplied compared to the theoretical amount. In other words, the excess air state is set at λ>1. Specifically, the air ratio λ is selected, for example, in the range of 2.8 to 12. As shown in Fig. 6, the air ratio λ = λ1 is selected for capacity 1, the air ratio λ = λ2 for capacity 2, the air ratio λ = λ3 for capacity 3, and the air ratio λ = λ4 (λ1 < λ2 < λ3 < λ4) for capacity 4.

[0053] Based on these results and conditions, the above combustion characteristic formula (2) was found as a combustion characteristic formula that approximates the experimental results shown in Figure 7. Then, when the relationship between the gas amount and the flame current for each capacity 1 to 4 was plotted based on the combustion characteristic formula (2), the results shown in Figure 8 were obtained. The results shown in FIG. 8 are stored in the storage unit 120 as characteristic information indicating the relationship between the amount of fuel gas and the calculated flame current value. In combustion control, the calculated flame current value I calculated by the combustion characteristic formula (2) f and the measured flame current value I of the flame rod 25 a The amount of gas and / or air supplied to the gas burner 20 is controlled based on the above. For example, as shown in Figure 9, the measured frame current value I a is the calculated frame current value I f When the air ratio λ is greater than the predetermined λ value (λ1 for capacity 1, λ2 for capacity 2, λ3 for capacity 3, and λ4 for capacity 4), the actual flame current value I a Calculate the frame current value I f The amount of fuel gas supplied is controlled to be reduced so that the actual flame current I a is the calculated frame current value I f When the air ratio λ is greater than the predetermined λ value, the actual flame current I a Calculate the frame current value I f In order to match this, the amount of fuel gas supplied is controlled to increase.

[0054] The correction amount calculation unit 121 calculates the actual measured flame current value I a Based on the capacity number information output by the capacity switching unit 114 and the characteristic information related to the combustion characteristic formula (2) stored in the memory unit 120 (characteristic information indicating the relationship between the gas amount and the flame current corresponding to the capacity number information), the actually measured flame current value I a Calculate the frame current value I f and make the deviation zero, that is, the actual frame current value I a Calculate the frame current value I f , and outputs the correction amount information to the target current calculation unit 117.

[0055] Next, the control operation of the gas combustion apparatus will be described with reference to the flowcharts shown in Figures 10 and 11. The control operation is performed by the control unit 110 based on the detection information of the various sensors described above and the characteristic information and map information stored in advance in the storage unit 120. First, when the operator opens the hot water tap 102, the flow rate of the water supply (Q w ) is judged to be equal to or greater than the specified water flow rate. w If it is determined that the flow rate (Q) is less than the specified water flow rate, the process returns to step S1. w If it is determined that the water flow rate is equal to or greater than the specified water flow rate, the process proceeds to step S2.

[0056] In step S2, the air amount adjusting valve 60 is set to an ignition opening degree specified for ignition. The ignition opening degree may be an opening degree that is set in advance in the rest state. Subsequently, in step S3, the fan 70 is started and rotates at a preset constant number of rotations (rotation speed). Subsequently, in step S4, the igniter 24 is activated, and in step S5, the gas amount regulating valve 40 and the gas switching valve 51 are opened to an ignition opening degree that supplies a flow rate necessary for ignition.

[0057] Then, in step S6, it is determined whether a flame is present in the gas burner 20 (whether a flame current is flowing) based on the detection signal of the flame rod 25. If it is determined that no flame is present (no flame current is flowing), it is determined in step S7 whether a specified time has elapsed based on the timer's timing. If it is determined that the specified time has not elapsed, the process returns to step S6 and it is again determined whether a flame is present. On the other hand, if it is determined that the specified time has elapsed, the gas amount adjustment valve 40 and the gas switch valve 51 are closed in step S8. Next, in step S9, the air amount adjustment valve 60 is set to the extinguishing opening. Next, in step S10, it is determined whether a specified time has elapsed based on the timer's timing. If it is determined that the specified time has not elapsed, the process returns to step S10. On the other hand, if it is determined that the specified time has elapsed, the fan 70 stops rotating in step S11. If it is determined in step S6 that a flame is present (that a flame current is flowing), the operation of the igniter 24 is stopped in step S12.

[0058] Subsequently, in step S13, combustion control is started. In the combustion control, the fan 70 is driven at a constant rotation speed so as to achieve the required output thermal power while maintaining a predetermined air ratio λ (λ1, λ2, λ3, λ4) corresponding to the capacity 1 to 4, and the calculated flame current value I obtained from the combustion characteristic formula (2) is f and the measured frame current value I a In order to control the amounts of gas and air supplied to the gas burner 20 based on the above, the openings of the gas amount adjusting valve 40 and the air amount adjusting valve 60 are adjusted as appropriate.

[0059] 11, the required output thermal power is calculated in step S131. The output thermal power is calculated in the control unit 110 based on information on the target thermal power, which is a feedforward amount output by the target thermal power calculation unit 111, and the corrected thermal power, which is a feedback amount output by the outlet temperature F / B control unit 112.

[0060] Subsequently, in step S132, the ON / OFF of gas switching valves 51, 52, and 53 is controlled. Whether gas switching valves 51, 52, and 53 are turned ON (open) or OFF (closed) is determined in capacity switching unit 114 based on the output thermal power information output by output thermal power calculation unit 113, and is determined by selecting one of capacity 1, capacity 2, capacity 3, and capacity 4. That is, when capacity 1 is selected, gas switching valve 51 is turned ON, when capacity 2 is selected, gas switching valves 51 and 52 are turned ON, when capacity 3 is selected, gas switching valves 52 and 53 are turned ON, and when capacity 4 is selected, gas switching valves 51, 52, and 53 are turned ON.

[0061] Next, in step S133, the number of combustion flames n, the total number of combustion flames N, the unit calorific value of gas H, the required air ratio m of gas, and the amount of gas Q, which are parameters of the combustion characteristic formula (2), are calculated according to the selected capacity. g ,Air volume Q a The value is set. Next, in step S134, the opening degree of the butterfly valve 61 of the air amount adjustment valve 60 is controlled. The opening degree of the butterfly valve 61 is controlled based on the air amount Q a Based on this, a pulse voltage is applied to the drive source 62 (stepping motor) of the air amount adjusting valve 60 in accordance with a command relating to the target opening output by the target opening calculation unit 115, and the air amount adjusting valve 60 is driven and controlled to achieve the target opening.

[0062] Next, in step S135, the current flowing through the gas amount regulating valve 40 is controlled. This current control is performed by the current control unit 118, which controls the gas amount Q g Based on the target current output by the target current calculation unit 117 and feedback information on the current, the current flowing through the gas amount adjustment valve 40 (proportional solenoid valve) is PWM controlled, and the amount of fuel gas supplied through the gas amount adjustment valve 40 is adjusted.

[0063] Subsequently, in step S136, the actually measured flame current value I of the flame rod 25 is aand the calculated flame current value I obtained by the combustion characteristic formula (2) in the memory unit 120. f and are compared in a correction amount calculation unit 121, and a correction amount according to the deviation between them is calculated. Next, in step 137, the target current calculation unit 117 calculates a corrected target current based on the above correction amount, and the current control unit 118 adjusts the opening of the gas amount adjustment valve 40 based on the corrected target current, thereby adjusting the amount of gas to be supplied. As described above, in step S13 including steps 131 to 137, combustion control is performed to monitor the combustion state in real time based on the combustion characteristic equation (2).

[0064] Next, in step S14, the flow rate of the water supply (Q w ) is judged to be equal to or less than the specified water flow rate. w If it is determined that the flow rate (Q) is equal to or less than the specified water flow rate, the process proceeds to step S8. w If it is determined that the water flow rate is not equal to or less than the specified water flow rate, the process proceeds to step S15. In step S15, it is determined whether or not a flame is present in the gas burner 20 based on the detection signal of the flame rod 25. If it is determined that no flame is present, the process proceeds to step S8. On the other hand, if it is determined that a flame is present, the process proceeds to step S16.

[0065] In step S16, it is determined whether or not there is an abnormality in the combustion state. If it is determined that there is an abnormality, the process proceeds to step S8. On the other hand, if it is determined that there is no abnormality, the process returns to step S13, and combustion control continues. Here, the determination of whether or not there is an abnormality is made by comparing the detection information detected by various sensors, the map information pre-stored in the memory unit 120, and the information calculated by the control unit 110. If the information is outside the expected range, it is determined that there is an abnormality, and if it is within the expected range, it is determined that there is no abnormality.

[0066] According to the gas combustion apparatus having the above configuration, the control unit 110 calculates the calculated flame current value I f and the measured flame current value I of the flame rod 25 a Based on this, the amount of gas supplied to the gas burner 20 is controlled, so even in a combustion state where excess air is present, the actual measured flame current value I obtained from one flame rod 25 is a With just this information, the combustion status can be grasped in real time. This simplifies the structure and reduces costs, and allows the desired output thermal power to be obtained while maintaining a good combustion state with low CO and NOx emissions in real time.

[0067] In particular, the gas burner 20 is a multi-stage switching gas burner that generates a plurality of capacities 1 to 4 with different amounts of gas supplied corresponding to the magnitude of the output thermal power, and the memory unit 120 contains characteristic information calculated based on the combustion characteristic formula (2) corresponding to the plurality of capacities, so that combustion control becomes possible to obtain an air ratio λ (λ1, λ2, λ3, λ4) appropriate for each of the capacities 1 to 4, and optimal combustion control can be performed for each of the capacities according to the magnitude of the output thermal power.

[0068] Furthermore, the gas combustion apparatus having the above configuration includes, as an air amount adjustment unit, the fan 70 that is driven to rotate at a constant rotation speed to generate an air flow toward the gas burner 20, and the air amount adjustment valve 60 that adjusts the amount of air supplied to the gas burner 20, so that the responsiveness of the air amount in a transient state is improved and control can be simplified compared to the conventional case where the air amount is adjusted by controlling the rotation speed of the fan. Also, because the fan 70 rotates at a constant rotation speed, noise, vibration, etc. that accompany fluctuations in rotation can be suppressed or prevented.

[0069] In particular, because the air amount control valve 60 includes a drive source 62 and a butterfly valve 61 that is driven to open and close by the drive source 62, the air passage area can be set large, and the air passage area can be quickly adjusted by simply rotating the butterfly valve 61, thereby quickly adjusting the amount of air to be supplied to a required level. By using a stepping motor as the drive source 62, feedback control is not required, and the opening of the butterfly valve 61 can be controlled with high precision. Furthermore, it includes a motor 72 that generates the rotational driving force of the fan 70, and by using an AC motor as the motor 72, it is easy to maintain a constant rotation number (rotational speed) according to the frequency, there is little unevenness in the rotational speed (rotational torque), and it is also suitable for a long life.

[0070] FIG. 12 shows a control unit that controls the overall operation and combustion of a gas combustion apparatus according to a second embodiment of the present invention. The same components as those in the control unit 110 according to the previous embodiment are designated by the same reference numerals and will not be described again. The control unit 210 according to the second embodiment includes a target thermal power calculation unit 111, an outlet temperature F / B control unit 112, an output thermal power calculation unit 113, a capacity switching unit 114, a target opening calculation unit 115 and opening control unit 116 for the air amount control valve 60, a target current calculation unit 117 and current control unit 118 for the gas amount control valve 40, a memory unit 120 for storing various control information, etc., a correction amount calculation unit 121, a target rotation speed calculation unit 211 for calculating the rotation speed of the fan 70, and a rotation control unit 212 for controlling the rotation of the fan 70.

[0071] The target rotation speed calculation unit 211 calculates the target rotation speed of the fan 70 from the map information stored in the memory unit 120, based on the output thermal power information output by the output thermal power calculation unit 113 and the capacity number information output by the capacity switching unit 114. Specifically, as map information, a fixed rotation speed N1 is set when the output firepower is capacity 1, a fixed rotation speed N2 (N2>N1) is set when the output firepower is capacity 2, a fixed rotation speed N3 (N3>N2>N1) is set when the output firepower is capacity 3, and a fixed rotation speed N4 (N4>N3>N2>N1) is set when the output firepower is capacity 4. Therefore, the target rotation speed calculation unit 211 determines which of the rotation speeds N1, N2, N3, and N4 to select depending on the capacity.

[0072] The rotation control unit 212 drives the motor 72 of the fan 70 to rotate at a constant rotation speed (N1, N2, N3, N4) based on the information related to the rotation speed output by the target rotation speed calculation unit 211 and feedback information on the actual rotation speed. That is, the control unit 210 drives the fan 70 to rotate at a constant rotation speed (N1, N2, N3, N4) set for each of a plurality of capacities (capacity 1, capacity 2, capacity 3, capacity 4). The number of rotations to be set is not limited to the four numbers of rotations described above, but may be two or three numbers of rotations.

[0073] According to the control method of the control unit 210 according to the second embodiment, in a combustion mode requiring a small output thermal power, the amount of air required is also small, and therefore by reducing the rotation speed of the fan 70, it is possible to suppress or prevent the throttling resistance and noise caused by the throttling resistance that accompany the opening and closing of the air amount control valve 60. On the other hand, in a combustion mode requiring a large output thermal power, the amount of air required is also large, and therefore by increasing the rotation speed of the fan 70, it is possible to obtain the desired output thermal power while maintaining a predetermined air ratio λ.

[0074] In the above embodiment, the control units 110, 210 are shown that control combustion based on the combustion characteristic equation of the present invention in a configuration in which the magnitude of output thermal power can be selected, but the present invention is not limited to this. Even in a gas combustion device that generates a single output thermal power, by controlling combustion based on the combustion characteristic equation of the present invention, it is possible to control combustion in real time to maintain a good combustion state with low CO and NOx emissions. In addition, in the above embodiment, a configuration is shown having four capacities (capacity 1 to capacity 4) as multiple capacities with different amounts of gas supplied corresponding to the magnitude of the output thermal power, but this is not limited to this, and two capacities, five capacities, or more capacities may be set. In the above embodiment, the gas burner 20 is configured to include a burner 1 having four first nozzles 21, a burner 2 having two second nozzles 22, and a burner 3 having nine third nozzles 23, but this is not limited to this, and the present invention may also be adopted in configurations including gas burners with other numbers of nozzles and burners.

[0075] In the above embodiment, the control unit 110, 210 calculates the calculated flame current value I f Although the method of controlling the amount of gas supplied to the gas burner 20 based on the actually measured flame current value has been described, the present invention is not limited to this, and a method of controlling the amount of air supplied to the gas burner 20 may also be adopted. In this case, the memory unit 120 may store characteristic information indicating the relationship between the amount of air supplied and the calculated flame current value. In the above embodiment, when the actual measured frame current value deviates from the calculated frame current value If, ​​the control unit 110, 210 converts the actual measured frame current value into the calculated frame current value I f However, the present invention is not limited to this, and a control method may be adopted in which other parameters are adjusted based on the deviation amount, thereby reducing or increasing the amount of gas and / or air.

[0076] In the above embodiment, the air amount adjustment valve is the air amount adjustment valve 60 including the butterfly valve 61 and the drive source 62 (stepping motor), but this is not limited to this, and air amount adjustment valves of other forms may be used as long as they can adjust the amount of air by opening and closing the passage through which air flows. Furthermore, although a stepping motor is shown as the drive source 62 for the air amount adjustment valve 60, a DC motor equipped with an opening sensor or the like may also be used as the drive source. In the above embodiment, an AC motor is used as the motor 72 of the fan 70, but the present invention is not limited to this, and a fan driven by a DC motor may also be used.

[0077] In the above embodiment, a gas water heater including a heat exchanger 80 is shown as the gas combustion device, but this is not limited to this, and the gas combustion device may be a gas combustion device for heating or any other form of gas combustion device as long as it utilizes the heat generated by the combustion of fuel gas.

[0078] In the above embodiment, the present invention is applied to a gas combustion device in which fuel gas and air are supplied separately, but the present invention is not limited to this and can also be applied to a gas combustion device in which fuel gas and air are pre-mixed and supplied to a gas burner.

[0079] As described above, the gas combustion device of the present invention achieves simplified structure and reduced costs, while being able to grasp the combustion state and maintain a good combustion state. It also has improved responsiveness to the amount of air to be supplied and can obtain the desired output thermal power. Therefore, it can be applied not only as a gas water heater that heats room temperature water to provide hot water as described above, but also as a bath water heater and other heating equipment that heats fluids. [Explanation of symbols]

[0080] 20 Gas burner 25 Frame Rod 30 Gas supply piping 40 Gas volume adjustment valve 51, 52, 53 Gas switching valve 60 Air volume adjustment valve (air volume adjustment unit) 61 Butterfly valve 62 Drive source (stepping motor) 70 Fan (Air volume adjustment unit) 72 Motor (AC motor) 80 heat exchanger 100 Hot water supply piping n Number of combustion flames N Total number of combustion flames H Gas unit calorific value m Gas required air rate Q g Gas volume Q a Air volume I f Calculated frame current value I a Measured frame current value k1 is a constant proportional to the number of flames contributing to the flame current k2 Constant that contributes to the applied voltage and resistance value of the flame rod 110 control unit 113 Output thermal power calculation unit 114 Ability Switching Unit 115 Target opening calculation unit 116 Opening control unit 120 Storage section 121 Correction amount calculation section 210 Control Unit 211 Target rotation speed calculation unit 212 Rotation control unit

Claims

1. a multi-stage switching gas burner that mixes fuel gas with air and burns it according to an output thermal power, and generates a plurality of capacities in which the amount of gas supplied varies according to the magnitude of the output thermal power; a flame rod that is exposed to the flame of the gas burner to generate a flame current; a gas amount adjusting valve for adjusting the amount of the fuel gas supplied to the gas burner; an air amount adjusting unit that adjusts the amount of air to be mixed with the fuel gas; a control unit that controls the gas amount adjustment valve and the air amount adjustment unit to control combustion, The control unit The number of combustion flames of the gas burner is n, the total number of combustion flames is N, the unit calorific value of the fuel gas is H, the required air ratio of the gas is m, and the gas amount is Q ｇ , air volume Q ａ , a constant proportional to the number of flames contributing to the flame current is k １ , the constant that contributes to the applied voltage and resistance value of the flame rod is k ２ Then, the combustion characteristic equation is as follows: I ｆ =[k １ ln(HQ) ｇ / n)+k ２ ]ex_[-(nQ ａ / NmQ ｇ -1) ２ ] The calculated frame current value I ｆ and controls the amount of gas and / or air supplied to the gas burner based on the measured flame current value of the flame rod, and includes a storage unit that stores characteristic information calculated based on the combustion characteristic formula corresponding to the plurality of capacities, an output thermal power calculation unit that calculates the output thermal power, a capacity switching unit that determines whether to switch to a required capacity based on the output thermal power information of the output thermal power calculation unit, and a correction amount calculation unit that compares the measured flame current value with the calculated flame current value and calculates a correction amount based on the deviation, and controls the gas amount adjustment valve based on the output thermal power information, capacity number information of the capacity switching unit, and correction amount information of the correction amount calculation unit. A gas combustion device characterized by:

2. When the actual measured flame current value deviates from the calculated flame current value, the control unit controls to decrease or increase the amount of gas and / or air so that the actual measured flame current value coincides with the calculated flame current value.

2. The gas combustion apparatus according to claim 1.

3. the characteristic information stored in the storage unit includes characteristic information indicating a relationship between the amount of the fuel gas and the calculated flame current value; 3. The gas combustion apparatus according to claim 1 or 2.

4. The control unit controls the air amount adjustment unit based on the output thermal power information and the capacity number information.

2. The gas combustion apparatus according to claim 1.

5. the air amount adjustment unit includes a fan that is driven to rotate at a constant rotation speed to generate an air flow toward the gas burner, and an air amount adjustment valve that adjusts the amount of air supplied to the gas burner, The control unit includes a target opening calculation unit that calculates a target opening of the air amount adjustment valve based on the output thermal power information and capacity number information of the capacity switching unit, and an opening control unit that controls the opening of the air amount adjustment valve based on the target opening information of the target opening calculation unit.

5. The gas combustion apparatus according to claim 1 or 4.

6. the control unit drives the fan to rotate at a constant rotation speed set for each of the plurality of capacities.

6. The gas combustion apparatus according to claim 5.

7. The control unit includes a target rotation speed calculation unit that calculates a target rotation speed of the fan based on the output firepower information and the capacity number information, and a rotation control unit that drives the fan to rotate at a constant rotation speed based on the target rotation speed information of the target rotation speed calculation unit.

7. The gas combustion apparatus according to claim 6.

8. The air amount adjustment valve includes a drive source and a butterfly valve that is driven to open and close by the drive source.

8. The gas combustion apparatus according to claim 5 or 7.

9. The drive source is a stepping motor.

9. The gas combustion device according to claim 8.

10. the fan includes a motor that generates a rotational driving force; The motor is an AC motor.

10. The gas combustion apparatus according to claim 8 or 9.

11. a heat exchanger disposed adjacent to the gas burner; 11. A gas combustion apparatus according to claim 1, wherein the gas combustion apparatus comprises:

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