JP6085965B2 - Water heater - Google Patents

Description

  The present invention relates to a hot water supply apparatus, and more particularly to combustion control in a hot water supply apparatus.

  Conventionally, a gas combustion type hot water supply apparatus has been used. In such a hot water supply apparatus, the amount of gas combustion required to heat the water flowing through the hot water supply pipe is calculated, and the air amount is appropriately controlled so as to maintain a predetermined air-fuel ratio (for example, the theoretical air-fuel ratio). It is necessary to perform air-fuel ratio control.

  In Patent Documents 1 to 4, air-fuel ratio control in a water heater configured to adjust the gas pressure supplied to the gas burner by controlling the opening of the gas proportional valve and to control the air amount by controlling the rotational speed of the fan. Is described. In Patent Document 1 (Japanese Patent Laid-Open No. 62-190322) and Patent Document 2 (Japanese Patent Laid-Open No. 1-252819), the driving state of a slow-responsive fan motor is detected, and based on this, the proportionality of a gas that has a quick response. Controlling the valve is described.

  Furthermore, Patent Document 3 (Japanese Patent No. 3603556) describes that the gas pressure is corrected at the time of rotational speed adjustment transient according to the deviation between the actual rotational speed of the combustion fan and the target rotational speed. In addition, there is described control for switching whether or not the gas pressure needs to be corrected according to the magnitude of the deviation.

  Japanese Patent No. 3533485 (Patent Document 4) describes an air-fuel ratio control apparatus in which the amount of gas supplied to a burner can be accurately adjusted to obtain an ideal air-fuel ratio. Yes.

Japanese Patent Laid-Open No. 62-190322 Japanese Patent Laid-Open No. 1-252819 Japanese Patent No. 3603556 Japanese Patent No. 3533485

  In Patent Documents 1 to 3, in the air-fuel ratio control of the gas burner, the gas pressure supplied to the burner is determined based on the detected value of the fan rotational speed in consideration of the difference in responsiveness between the fan and the gas proportional valve. The adjustment is described.

  However, in general, the fan rotation speed is detected by counting the rotation speed of the mechanism attached to the rotating body. Therefore, in the transient state where the rotation speed changes, the detected value of the fan rotation speed includes a delay. It will be. In the control for supplying the gas amount directly corresponding to the detected value of the fan rotation speed, the air-fuel ratio may fluctuate due to the influence of the detection delay. In particular, there is a concern that it will be difficult to maintain the air-fuel ratio appropriately throughout the transient period. In Patent Document 3, the control is complicated because the necessity of correcting the gas pressure is switched.

  Combustion control for maintaining such an air-fuel ratio can be an important issue not only for combustion control in a hot water supply apparatus, but also for all combustion apparatuses that combust a mixture of gas and air.

  The present invention has been made in view of the above problems, and an object of the present invention is to control the air amount by controlling the rotational speed of the fan in the air-fuel ratio control of the gas burner in which the supply air amount is controlled by controlling the rotational speed of the fan. In this configuration, the air-fuel ratio is maintained throughout the transient state when the target rotational speed of the fan is changed.

  According to the hot water supply apparatus of the present invention, the gas combustion type hot water supply apparatus includes a burner for burning a mixture of fuel gas and combustion air, a control valve for controlling the supply pressure of the fuel gas to the burner, and a rotation. A combustion fan for supplying combustion air with an amount of air corresponding to the number, a control means, a fan control unit for controlling the rotation speed of the combustion fan according to the target rotation speed, and for detecting the rotation speed of the combustion fan Rotation speed detector. The control means has a target gas pressure corresponding to a supply pressure for generating the target generated heat amount and a predetermined air-fuel ratio for the fuel gas supplied by the target gas pressure in accordance with the target generated heat amount in the burner. A target rotational speed corresponding to the rotational speed for supplying the air amount by the combustion fan is set. Further, the control means supplies a supply pressure for supplying a fuel gas having a predetermined air-fuel ratio with respect to the amount of air supplied by the combustion fan at the rotation speed according to the detection value based on the detection value by the rotation speed detector. A means for determining the present ideal gas pressure, a means for setting a command gas pressure to the control valve by correcting the ideal gas pressure according to a deviation between the target gas pressure and the ideal gas pressure, and according to the command gas pressure Means for controlling the supply pressure by the control valve.

  In the hot water supply apparatus described above, air-fuel ratio control is performed based on the actual rotational speed of the combustion fan having low responsiveness in a transient state where the rotational speed of the combustion fan is changing toward the target rotational speed corresponding to the target generated heat amount. , The ideal gas pressure calculated based on the detected value of the fan rotational speed can be corrected with a correction amount corresponding to the deviation of the target gas pressure corresponding to the ideal gas pressure and the target rotational speed. . As a result, it is possible to compensate for the detection delay of the rotational speed of the combustion fan and maintain the air-fuel ratio appropriately throughout the transient state period.

  Preferably, in the above-described hot water supply apparatus, the control means further includes means for setting the command gas pressure so that a correction gas pressure that is a difference between the command gas pressure and the ideal gas pressure is proportional to the deviation.

  In this way, the correction gas pressure can be set according to the deviation between the ideal gas pressure and the target gas pressure, and the correction gas pressure is reduced to zero in the steady state where the detected value of the rotation speed of the combustion fan matches the target rotation speed. Can be. As a result, the command gas pressure setting method can be shared between the transient state where the detection delay of the combustion fan speed occurs and the steady state where the detection delay does not occur, simplifying the control process of the air-fuel ratio control can do.

  Preferably, in the hot water supply apparatus described above, the control means is configured such that when the target gas pressure is higher than the ideal gas pressure, the proportional constant (absolute value) is compared with the case where the target gas pressure is lower than the ideal gas pressure. ) Is further included.

  This makes it possible to appropriately compensate for the detection delay of the rotational speed of the combustion fan in accordance with the difference in the rotational speed change rate between when the rotational speed of the combustion fan increases and when it decreases. Therefore, the air-fuel ratio can be properly maintained.

  Preferably, in the hot water supply apparatus described above, the control means further includes means for calculating a target heat generation amount based on a product of a flow rate of the hot water supply apparatus and a temperature difference between an incoming water temperature and a set temperature of the hot water supply apparatus.

  If it does in this way, the change of the hot water supply load in a hot water supply apparatus can be reflected appropriately in target heat generation amount.

  As described above, according to the present invention, in the air-fuel ratio control of the gas burner in which the amount of supplied air is controlled by controlling the rotational speed of the fan, the air-fuel ratio is maintained throughout the transient period when the target rotational speed of the fan is changed. be able to.

It is the schematic which shows the whole structure of the hot-water supply apparatus according to embodiment of this invention. 2 is a flowchart for explaining combustion control by a hot water supply control unit shown in FIG. 1. It is a conceptual waveform diagram for explaining the behavior of the rotational speed of the combustion fan in a transient state. FIG. 6 is a conceptual waveform diagram for explaining detection delay of a change in the rotational speed of a combustion fan in a transient state. It is a conceptual diagram explaining the comparative example of gas pressure correction. It is a conceptual diagram explaining the gas pressure correction at the time of a fan rotation speed rise in the hot water supply device according to the present embodiment. It is a conceptual diagram explaining the gas pressure correction | amendment at the time of the fan rotation speed fall in the hot water supply apparatus according to this Embodiment. It is the schematic explaining the whole structure of the gas fan heater which is an example of the combustion apparatus with which this invention is applied.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the following, the same or corresponding parts in the drawings are denoted by the same reference numerals, and the description thereof will not be repeated in principle.

FIG. 1 is a schematic diagram showing an overall configuration of a hot water supply apparatus 100 according to an embodiment of the present invention.
Referring to FIG. 1, hot water supply apparatus 100 includes a can body 110, a combustion fan 160, a hot water supply pipe 180, a gas supply pipe 190, and a hot water supply control unit 300.

  Inside the can body 110, a heat exchanger 130 for heating the water flowing through the hot water supply pipe 180 and the gas burner 120 are accommodated. The gas burner 120 generates heat by burning the gas supplied from the gas supply pipe 190. The gas burner 120 is disposed close to the heat exchanger 130, and the amount of heat generated by the combustion of the gas burner 120 is transmitted to the water flowing through the hot water supply pipe 180 through the heat exchanger 130.

  The can body 110 is provided with an exhaust port 140 and an intake port 150. Combustion fan 160 is connected to intake port 150 and forcibly supplies combustion air into can 110. The exhaust port 140 discharges the exhaust after combustion to the outside of the can body 110.

  A gas proportional valve 200 is inserted and connected to the gas supply pipe 190. The gas proportional valve 200 is composed of, for example, a proportional electromagnetic valve. The gas pressure supplied to the gas burner 120 is controlled by the opening degree control of the gas proportional valve 200 according to the command from the hot water supply control unit 300. The gas supply amount per unit time to the gas burner 120 is controlled by controlling the gas pressure.

  The gas burner 120 is provided with a plurality of combustion pipes 125. The burner control unit 320 has a function of controlling the number of combustion pipes 125 to be supplied with fuel in response to a command from the hot water supply control unit 300. The burner control unit 320 has a function of controlling an electromagnetic valve (not shown) that is connected between the gas supply pipe 190 and each combustion pipe 125 and is controlled to open and close. The amount of heat output from the gas burner 120 to the heat exchanger 130 can be controlled by a combination of the number of combustion tubes 125 supplied with fuel and the gas pressure.

  Combustion fan 160 is driven by DC motor 170. The amount of air supplied from the combustion fan 160 to the can body 110 changes according to the rotational speed of the combustion fan 160. The rotational speed of combustion fan 160 is controlled by a fan drive voltage supplied to DC motor 170 from a power converter (not shown). The rotational speed of the combustion fan 160 is detected by the fan rotational speed detector 240. The fan rotation speed detection unit 240 is configured by, for example, an electromagnetic pickup type sensor attached to the rotating body of the combustion fan 160 or the DC motor 170.

  Fan control unit 310 controls the rotational speed of combustion fan 160 in accordance with target fan rotational speed Fr instructed from hot water supply control unit 300. Specifically, feedback control for increasing or decreasing the fan drive voltage is executed based on a comparison between the detected fan speed Fc detected by the fan speed detector 240 and the target fan speed Fr.

  The hot water supply pipe 180 is provided with a flow rate sensor 210 and temperature sensors 220 and 230. A hot water tap (not shown) is connected to the tip of the hot water supply pipe 180. When the hot-water tap is opened, the flow rate Q> 0. The flow rate Q changes according to the opening degree of the hot water tap. The flow rate sensor 210 detects the flow rate Q of the hot water supply pipe 180. The temperature sensor 220 is provided on the downstream side of the heat exchanger 130 and detects the tapping temperature Th. On the other hand, the temperature sensor 220 is provided on the upstream side of the heat exchanger 130 and detects the incoming water temperature Tc.

  The set temperature Tr * of the hot water supply device 100 is input to the hot water supply control unit 300. Further, detection values by flow sensor 210, temperature sensors 220 and 230, and fan rotation speed detection unit 240 are input to hot water supply control unit 300. Hot water supply control unit 300 performs combustion control so that the temperature of hot water discharged from hot water supply pipe 180 is controlled according to set temperature Tr *. The hot water supply control unit 300 outputs a control command for controlling the opening degree of the gas proportional valve 200 to the gas proportional valve 200 and outputs the target fan rotational speed Fr of the combustion fan 160 to the fan control unit 310. The function of hot water supply control unit 300 is realized by a microcomputer, for example.

  FIG. 2 is a flowchart for explaining combustion control of hot water supply apparatus 100 by hot water supply control unit 300.

  Referring to FIG. 2, hot water supply control unit 300 compares flow rate Q of hot water supply pipe 180 with the minimum operating flow rate (MOQ) in step S100. If the flow rate Q is too small, the detection by the flow rate sensor 210 may be inaccurate or boiling may occur in the heat exchanger 130. The minimum operating flow rate (MOQ) is set to the minimum flow rate at which the hot water supply device 100 can operate stably without causing these problems.

  When Q <MOQ (NO in S100), combustion is stopped in hot water supply apparatus 100. For this reason, hot water supply control unit 300 does not execute steps S100 to S160 for combustion control.

  When Q ≧ MOQ (when YES is determined in S100), hot water supply control unit 300 executes the processes of steps S110 to S160 for executing a series of combustion controls. In step S110, hot water supply control unit 300 calculates a target heat generation amount based on set temperature Tr *, incoming water temperature Tc, and flow rate Q. In hot water supply apparatus 100, the target heat generation amount is generally calculated as a target number. The target number is expressed by the following equation (1).

Target number = (Tr * −Tc) · Q / 25 (1)
(Tr * −Tc) corresponds to a target temperature increase amount in the heat exchanger 130. From the product of the target temperature increase amount and the flow rate Q, the amount of heat required to increase the water temperature is obtained as the target generated heat amount.

  In step S120, hot water supply control unit 300 determines final target gas pressure Pr and target fan rotation speed Fr according to the target number obtained in step S110. For example, taking into account the efficiency in the gas burner 120 and the heat exchanger 130, a table for determining the gas pressure required to generate the amount of heat corresponding to the target number is created in advance. Therefore, the final target gas pressure Pr can be determined by reading the gas pressure corresponding to the target number obtained in step S110 by referring to the table. That is, the final target gas pressure Pr corresponds to a gas pressure for generating a target heat generation amount (target number).

  The target fan speed Fr burns the amount of air whose air-fuel ratio with the gas amount becomes a predetermined value (for example, the ideal air-fuel ratio) when the gas amount corresponding to the final target gas pressure Pr is supplied to the gas burner 120. This corresponds to the rotation speed when the fan 160 supplies. That is, the target fan rotational speed Fr is determined corresponding to the final target gas pressure Pr. Therefore, similarly to the final target gas pressure Pr, a table for determining the target fan speed Fr in correspondence with the target number can be created in advance.

  When the opening of the gas proportional valve 200 is set to an opening corresponding to the final target gas pressure Pr, and the rotation speed of the combustion fan 160 is equal to the target fan rotation speed Fr, combustion in the gas burner 120 is performed at a predetermined level. It is understood that an ideal state according to the air-fuel ratio (theoretical air-fuel ratio) is obtained.

  In step S130, the hot water supply control unit 300 outputs the target fan rotation speed Fr determined in step S120 to the fan control unit 310. The fan control unit 310 controls the rotational speed of the combustion fan 160 according to the target fan rotational speed Fr.

  When the target number (target heat generation amount) changes due to changes in the set temperature Tr * and the flow rate Q, the final target gas pressure Pr and the target fan speed Fr change accordingly. The fan control unit 310 controls the rotational speed of the combustion fan 160 so as to follow the change in the target fan rotational speed Fr. However, since the responsiveness of the rotational speed control of the combustion fan 160 is low, a transient state in which the target fan rotational speed Fr and the actual rotational speed do not coincide occurs in the rotational speed control of the combustion fan 160.

  Referring to FIG. 3, at time t1, target fan rotational speed Fr changes from F1 to F2. In response to this, the fan control unit 310 controls the fan drive voltage supplied to the DC motor 170 so as to increase the fan rotation speed.

  However, the actual rotational speed Fm (hereinafter referred to as the actual rotational speed Fm) changes so as to have a certain delay with respect to the change in the target fan rotational speed Fr. As pointed out in Patent Documents 1 to 3, since the responsiveness of the rotational speed control of the combustion fan 160 is lower than the responsiveness of the opening degree control of the gas proportional valve 200, in the transient state, the target fan rotational speed Fr. If the gas pressure, that is, the opening degree of the gas proportional valve 200 is controlled according to the final target gas pressure Pr corresponding to, the air-fuel ratio may change. Specifically, in the transient state illustrated in FIG. 3 where the actual rotational speed Fm is lower than the target fan rotational speed Fr, the gas supply may be excessive. Conversely, in a transient state where the actual rotational speed Fm is higher than the target fan rotational speed Fr, there is a possibility that the gas supply will be insufficient. In such a combustion state that deviates from the stoichiometric air-fuel ratio, there is a concern that exhaust properties may deteriorate due to unburned gas, or combustion failure may occur.

  Referring to FIG. 2 again, in step S140, hot water supply control unit 300 determines a predetermined value based on fan rotation speed Fc detected by fan rotation speed detection unit 240 in order to cope with the problem described with reference to FIG. An ideal gas pressure Pi for maintaining the air-fuel ratio is determined.

  FIG. 4 is a conceptual waveform diagram for explaining the detection delay of the change in the rotational speed of the combustion fan in the transient state.

  Referring to FIG. 4, when target fan rotational speed Fr of combustion fan 160 changes at time t1, actual rotational speed Fm changes from F1 toward target fan rotational speed Fr by rotational speed control. At time t2, the actual rotational speed Fm increases to the target fan rotational speed Fr. On the other hand, the fan rotation speed detection unit 240 outputs the detected fan rotation speed Fc based on the rotation speed of the rotating body within a certain period up to the present time. For this reason, in the transient state where the actual rotational speed Fm is changing toward the target fan rotational speed Fr, the detected fan rotational speed Fc has a detection delay with respect to the change in the actual rotational speed Fm.

  In the example of FIG. 4 in which the actual rotational speed Fm is increasing, the detected fan rotational speed Fc is a value lower than the actual rotational speed Fm. For this reason, if the gas proportional valve 200 is controlled according to the ideal gas pressure Pi set based on the detected fan rotation speed Fc, the gas pressure is too low to supply a necessary amount of gas, which may lead to poor combustion. .

  On the other hand, in a scene where the actual rotational speed Fm is decreasing, if the gas proportional valve 200 is controlled according to the ideal gas pressure Pi set based on the detected fan rotational speed Fc, the gas pressure is too high and the gas amount is excessive. Therefore, there is a concern about deterioration of exhaust properties due to unburned gas.

  Referring to FIG. 2 again, in step S150, hot water supply control unit 300 performs gas pressure correction to compensate for the detection delay of the fan rotation speed with respect to ideal gas pressure Pi, and supplies gas proportional valve 200 to gas proportional valve 200. The command gas pressure Pc is determined. Further, the hot water supply control unit 300 controls the gas proportional valve 200 according to the command gas pressure Pc in step S160. That is, a gas amount according to the command gas pressure Pc is supplied from the gas burner 120.

  First, a comparative example of gas pressure correction will be described with reference to FIG. FIG. 5 shows a gas pressure correction for dealing with a detection delay with respect to the fan rotational speed behavior similar to that in FIG.

  Referring to FIG. 5, ideal gas pressure Pi is a gas pressure for maintaining a predetermined air-fuel ratio with respect to the air amount corresponding to detected fan rotation speed Fc. The ideal gas pressure Pi is P1 corresponding to a gas pressure that becomes a predetermined air-fuel ratio at the time t1 when the fan rotation speed is F1 (FIG. 4). After time t1, the ideal gas pressure Pi increases corresponding to the increase in the detected fan rotation speed Fc shown in FIG. The ideal gas pressure Pi reaches the final target gas pressure Pr at a timing (time t2 in FIG. 4) when the detected fan rotation speed Fc matches the target fan rotation speed Fr.

  In the gas pressure correction according to the comparative example, the detection fan speed Fc is reflected in the transient state period until the ideal gas pressure Pi reaches the final target gas pressure Pr, reflecting the point that the detected fan speed Fc is lower than the actual speed Fm. The command gas pressure Pc is set by correcting the ideal gas pressure Pi based on the rotational speed Fc by k times (k> 1.0 in the example of FIG. 4). That is, Pc = k · Pi is set.

  In this gas pressure correction, the detection delay in the transient state is regarded as substantially constant, and the shortage or excess of the gas pressure corresponding to the detection delay is compensated. On the other hand, as shown in FIG. 4, the difference between the actual rotational speed Fm and the detected fan rotational speed Fc becomes small at the start and end of the transient state period, but becomes a substantially constant value in other sections. Therefore, it is difficult to appropriately set the value of the correction coefficient k throughout the transient state period (time t1 to t2). Further, since it is necessary to turn off the gas pressure correction in the steady state, the steady state and transient state determination processing and control switching processing are required as in Patent Document 3.

  FIG. 6 is a conceptual diagram illustrating gas pressure correction when the fan rotation speed is increased in the hot water supply apparatus according to the present embodiment.

  Referring to FIG. 6, the ideal gas pressure Pi is set based on the air amount corresponding to the detected fan rotational speed Fc shown in FIG. 4, similarly to FIG. 5. As in FIG. 5, when the fan speed increases, it is necessary to execute gas correction so that the correction amount ΔP> 0.

  In the gas pressure correction according to the present embodiment, the magnitude of the correction amount ΔPc (| ΔPc |) depends on the magnitude of deviation (| Pr−Pi |) between the current ideal gas pressure Pi and the final target gas pressure Pr. Is set. That is, the larger the absolute value of deviation (| Pr−Pi |) is, the larger the absolute value (| ΔPc |) of the correction amount is set. The smaller the absolute value of deviation is, the smaller the absolute value of the correction amount is set. When the correction amount ΔPc is used, the command gas pressure Pc is expressed by equation (2).

Pc = Pi + ΔPc (2)
For example, the correction amount ΔPc is calculated according to the equation (3) so as to be proportional to the deviation between the final target gas pressure Pr and the ideal gas pressure Pi.

ΔPc = k · (Pr−Pi) (3)
As a result, the correction amount does not become excessive when the ideal gas pressure Pi approaches the final target gas pressure Pr as in the correction shown in FIG. 5, and sufficient gas pressure correction is performed in the initial stage. Can be performed.

  FIG. 7 is a conceptual diagram illustrating gas pressure correction when the fan rotation speed is reduced in the hot water supply apparatus according to the present embodiment.

  Referring to FIG. 7, when the final target gas pressure Pr decreases from the ideal gas pressure Pi = P2, a transitional state occurs in which the fan speed decreases toward the target fan speed. At this time, the detected fan rotational speed Fc becomes higher than the actual rotational speed Fm due to the influence of the detection delay of the fan rotational speed. Therefore, if the gas proportional valve 200 is controlled using the ideal gas pressure Pi based on the detected fan rotation speed Fc, there is a possibility that gas is excessively supplied.

  Therefore, when the fan rotational speed decreases, it is necessary to perform gas pressure correction so that the correction amount ΔPc <0 in equation (2). Even when the rotational speed is decreased, the absolute value (| ΔPc |) of the correction amount is set according to the absolute value (| Pr−Pi |) of the deviation between the current ideal gas pressure Pi and the final target gas pressure Pr. . That is, the larger the absolute value of the deviation, the larger the absolute value of the correction amount, and the smaller the absolute value of the deviation, the smaller the absolute value of the correction amount.

  For example, the correction amount ΔPc can be commonly used when the rotational speed is reduced. As a result, it is possible to perform sufficient gas pressure correction in a scene where the deviation between the current ideal gas pressure Pi and the final target gas pressure Pr is large, and to prevent excessive gas pressure correction in a scene where the deviation is small. it can.

  It should be noted that the correction coefficient k in equation (3) may be a different value between when the fan speed is increased (FIG. 6) and when the fan speed is decreased (FIG. 7). In general, the rate of decrease when the fan speed decreases is slower than the rate of increase when the fan speed increases. Accordingly, the correction coefficient k may be set to a larger value when the fan speed is increased (that is, when the gas pressure is increased) than when the fan speed is decreased (that is, when the gas pressure is decreased). preferable.

  Alternatively, the expression (3) may be modified so that the correction amount ΔPc is calculated according to the absolute value of the deviation as in the following expression (4).

ΔPc = k · | Pr−Pi | (4)
In this case, k> 0 is set when the fan speed is increased (that is, when the gas pressure is increased), while k <0 is set when the fan speed is decreased (that is, when the gas pressure is decreased). There is a need. Also in this case, the absolute value (| k |) of the correction coefficient can be made larger when the fan rotational speed is increased than when the fan rotational speed is decreased.

  As described above, according to the hot water supply device according to the embodiment of the present invention, in a transient state where the rotational speed of the combustion fan is changing toward the target fan rotational speed Fr corresponding to the target generated heat amount, the gas proportional valve The air-fuel ratio control can be executed based on the actual rotational speed of the combustion fan 160 that is less responsive than 200. Further, the ideal gas pressure Pi calculated based on the detected fan rotation speed Fc is corrected by a correction amount ΔPc corresponding to the deviation of the final target gas pressure Pr corresponding to the ideal gas pressure Pi and the target fan rotation speed Fr. Can do. As a result, it is possible to compensate for the detection delay of the fan rotation speed and appropriately maintain the air-fuel ratio throughout the transient state period.

  Further, according to the equations (3) and (4), in a steady state, that is, in a steady state where the detected fan rotational speed Fc is equal to the target fan rotational speed Fr, ΔPc = 0, so that the expression is similar to the transient state. Even if (3) or (4) is applied, the gas pressure correction is automatically disabled. Thereby, it is also possible to share the setting process (FIG. 2) of the command gas pressure Pc between the steady state and the transient state. In this case, in the comparative example of FIG. 5, it is necessary to determine whether or not to perform the gas pressure correction based on whether or not the state is a transient state, whereas the air-fuel ratio control process is simplified. It becomes possible.

  In the present embodiment, the hot water supply apparatus provided with the gas combustion mechanism is illustrated, but the air-fuel ratio control in the gas combustion mechanism applied to the hot water supply apparatus according to the present embodiment is not limited to the hot water supply apparatus, and combustion of fuel gas The present invention can be commonly applied to a combustion apparatus having a mechanism.

  FIG. 8 shows a configuration example of a gas fan heater as an example of a combustion apparatus to which the present invention can be applied in addition to a hot water supply apparatus. As is well known, a gas fan heater performs warm air heating by outputting warm air obtained by gas combustion heat.

  Referring to FIG. 8, in gas fan heater 500, an exterior case 506, a top plate 514, and a bottom plate 515 constitute an exterior of the device. The outer case 506 has a warm air outlet 505 and an air inlet 507. The warm air outlet 505 is provided at a position that hits the lower part of the front surface. The air inlet 507 is provided at a position corresponding to the upper back of the device. An air filter 508 is provided at the air inlet 507. A room temperature detector 509 is provided in the vicinity of the air inlet 507. The room temperature detector 509 detects the ambient temperature taken in from the air inlet 507.

  Inside the outer case 506, a gas burner 501, a combustion chamber 502, a blower fan 503, a fan motor 504, and an ignition device 517 are provided. The combustion chamber 502 is provided inside the outer case 506.

  The blower fan 503 is provided in the lower part of the combustion chamber 502. The fan motor 504 drives the blower fan 503. The fan motor 504 is provided with a rotation speed detector 520 for detecting the rotation speed.

  The amount of air mixed with fuel gas in the gas burner 501 is controlled by the rotational speed of the blower fan 503. That is, the blower fan 503 has a function equivalent to that of the combustion fan 160 shown in FIG.

  A lid plate 518 is provided on the upper surface and the front surface of the combustion chamber 502. The fan case 519 is configured to guide the warm air from the blower fan 503 to the warm air outlet 505.

  A gas connection port 521 is provided at the lower back of the outer case 506. Combustion gas supplied to the gas connection port 521 includes an electromagnetic valve 522 for shutting off the gas, a gas proportional valve 523 for adjusting a gas pressure (that is, a gas amount per unit time), and a gas pipe 524. Then, the gas is supplied to the gas burner 501. The amount of heat generated by the gas burner 501 is controlled by the gas supply amount (gas pressure).

  A gas supply amount to the gas burner 501, that is, a gas pressure is controlled by a gas proportional valve 523. That is, the gas proportional valve 523 has a function equivalent to that of the gas proportional valve 200 shown in FIG.

  An operation display unit 512 is provided in front of the top plate 514. The operation display unit 512 can set hot air supply conditions such as hot air temperature.

  Below the operation display unit 512, an operation display circuit 513a in which switches and indicators are installed is provided. The operation display unit 512 is provided with a clogging indicator 511. The temperature detector 510 is constituted by a thermistor for detecting the temperature of the combustion chamber 502. Based on the combustion chamber temperature detected by the temperature detector 510, clogging of the air filter 508 is detected. The occurrence of clogging is notified to the user by a clogging indicator 511.

  The control circuit 513 controls the operation of the gas fan heater 500 according to a user input to a switch provided in the operation display unit 512. Typically, the gas supply to the gas burner 501, the ignition and extinguishing of the gas burner 501, the rotational speed of the blower fan 503, and the like are controlled so that warm air corresponding to the set temperature is output. When power is supplied to the control circuit 513 by connecting the power cord 526 to an outlet, the gas fan heater 500 is ready for operation.

  When the gas fan heater 500 starts the heating operation, the control circuit 513 starts the fan motor 504 and supplies gas to the gas burner 501. Indoor air is sucked into the exterior case 506 from the air suction port 507 by the blower fan 503. Part of the sucked air enters the combustion chamber 502 and is mixed with gas fuel by the gas burner 501 and burned.

  At this time, the control circuit 513 adjusts the gas supply amount and the rotational speed of the fan motor 504 so as to continue combustion.

  After the combustion gas in the gas burner 501 is discharged from the combustion chamber 502, it merges with the air flowing through the passage formed by the combustion chamber 502 and the cover plate 518 and is sucked into the blower fan 503. The warm air discharged from the blower fan 503 is guided to the warm air outlet 505 by the fan case 519 and released into the room.

  The control circuit 513 sets the target heat generation amount in the gas burner 501, that is, the gas combustion amount, according to the difference between the set temperature and the room temperature detected by the room temperature detector 509. The control circuit 513 controls the opening degree of the gas proportional valve 523 according to the set gas combustion amount.

  Further, the control circuit 513 controls the amount of air supplied to the gas burner 501 by controlling the rotational speed of the blower fan 503 by the fan motor 504. In accordance with air-fuel ratio control for maintaining the air-fuel ratio in the gas burner 501 at a predetermined air-fuel ratio (theoretical air-fuel ratio), the amount of gas supplied to the gas burner 501 (gas pressure) and the rotational speed of the blower fan 503 are controlled.

  As described above, also in the gas fan heater 500 shown in FIG. 8, the gas pressure and the amount of air supplied to the gas burner 120 are controlled by the valve opening degree and the fan rotation speed as in the hot water supply device 100 shown in FIG. 1. It is understood that Therefore, air-fuel ratio control in gas fan heater 500 can also be executed in the same manner as hot water supply apparatus 100 according to the present embodiment.

  Specifically, in the gas fan heater 500, the target heat generation amount and the final target gas pressure Pr are calculated based on the user settings input to the operation display unit 512, similarly to the hot water supply apparatus 100 shown in FIG. Can do. Furthermore, the hot water supply apparatus 100 shown in FIG. 1 is set so that the ratio of the supply air amount by the blower fan 503 becomes a predetermined air-fuel ratio (for example, the ideal air-fuel ratio) at the time of gas supply at the final target gas pressure Pr. Similarly, the target fan rotational speed Fr of the blower fan 503 can be set from the final target gas pressure.

  The rotational speed of the blower fan 503 is controlled by the fan motor 504 based on the detected value by the rotational speed detector 520, similarly to the combustion fan 160 in the hot water supply apparatus 100 shown in FIG. Therefore, the control circuit 513 calculates the ideal gas pressure Pi by the air-fuel ratio control based on the detection value by the rotation speed detector 520, as well as the hot water supply apparatus 100 of FIG. By correcting the ideal gas pressure Pi in accordance with the deviation, the gas pressure command value to the gas proportional valve 523 can be set similarly to the hot water supply apparatus 100 shown in FIG.

  Thereby, the air-fuel ratio control similar to that of hot water supply apparatus 100 shown in FIG. 1 can be performed by compensating for the delay in detecting the rotational speed of blower fan 503 by rotational speed detector 520. As a result, it is possible to continue combustion in the gas burner 501 maintaining a predetermined air-fuel ratio (ideal air-fuel ratio) in a transient state where the rotational speed of the blower fan 503 changes.

  Note that, in addition to the gas fan heater, any device (combustion device) having a combustion mechanism for combusting a mixture of gas and air can be used for the combustion mechanism according to the present embodiment. It goes without saying that the fuel ratio control can be similarly applied.

  In the hot water supply apparatus 100, the fan control unit 310, the burner control unit 320, and the fan rotation speed detection unit 240 may all be configured separately from the hot water supply control unit 300, or part or all of them may be controlled by hot water supply. You may comprise integrally with the part 300. FIG. For example, each function of the hot water supply control unit 300, the fan control unit 310, the burner control unit 320, and the fan rotation speed detection unit 240 can be realized by a single microcomputer.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  The present invention can be advantageously applied to equipment having a combustion mechanism for burning a gas-air mixture, such as a hot water supply apparatus.

  DESCRIPTION OF SYMBOLS 100 Hot-water supply apparatus, 110 Can body, 120 Gas burner, 125 Combustion pipe, 130 Heat exchanger, 140 Exhaust port, 150 Intake port, 160 Combustion fan, 170 DC motor, 180 Hot-water supply pipe, 190 Gas supply pipe, 200 Gas proportional valve, 210 Flow sensor, 220, 230 Temperature sensor, 240 Fan rotation speed detection unit, 300 Hot water supply control unit, 310 Fan control unit, 320 Burner control unit, 500 Gas fan heater, 501 Gas burner, 502 Combustion chamber, 503 Blower fan, 504 fan Motor, 505 Air outlet, 506 Exterior case, 507 Air inlet, 508 Air filter, 509 Room temperature detector, 510 Temperature detector, 511 Clogging indicator, 512 Operation display section, 513 Control circuit, 513a Operation display circuit, 514 Top plate, 51 Bottom plate, 517 Ignition device, 518 Cover plate, 519 Fan case, 520 Rotational speed detector, 521 Gas connection port, 522 Solenoid valve, 523 Gas proportional valve, 524 Gas piping, 526 Power cord, Fc detection fan rotational speed, Fm fan Actual speed, Fr target fan speed, Pc command gas pressure, Pi ideal gas pressure, Pr final target gas pressure, Q flow rate, Tc inlet water temperature, Th hot water temperature, Tr set temperature, k correction factor.

Claims (2)

A gas-fired water heater,
A burner for burning a mixture of fuel gas and combustion air;
A control valve for controlling the supply pressure of the fuel gas to the burner;
A combustion fan for supplying the combustion air with an air amount corresponding to the rotational speed;
According to the target heat generation amount in the burner, a target gas pressure corresponding to a supply pressure for generating the target heat generation amount, and an air amount that becomes a predetermined air-fuel ratio with respect to the fuel gas supplied by the target gas pressure Control means for setting a target rotational speed corresponding to the rotational speed to be supplied by the combustion fan;
A fan controller for controlling the rotational speed of the combustion fan according to the target rotational speed;
A rotational speed detector for detecting the rotational speed of the combustion fan,
The control means includes
A supply pressure for supplying the fuel gas having a predetermined air-fuel ratio with respect to the amount of air supplied by the combustion fan based on the detection value by the rotation speed detector based on the rotation speed according to the detection value. A means of determining the current ideal gas pressure;
Means for setting a command gas pressure to the control valve by correcting the ideal gas pressure according to a deviation between the target gas pressure and the ideal gas pressure;
Look including a means for controlling the supply pressure by the control valve in accordance with said command gas pressure,
The control means includes
Means for setting the command gas pressure such that a correction gas pressure, which is a difference between the command gas pressure and the ideal gas pressure, is proportional to the deviation;
When the target gas pressure is higher than the ideal gas pressure, the absolute value of the proportional constant of the correction gas pressure with respect to the deviation is increased as compared with the case where the target gas pressure is lower than the ideal gas pressure. And a hot water supply device. The control means includes
And the flow rate of the water heater, on the basis of the product of the temperature difference between the incoming water temperature and the set temperature of the water heater, further comprising Claim 1 Symbol mounting of the water heater means for calculating the target quantity of heat generated.

Images