JP2018071812A - Water heater and control method of water heater - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform combustion control based on a predicted flow rate so that a hot water tapping temperature becomes a proper temperature.SOLUTION: A water heater includes: a heating part (20) including a heat exchanger and a burner for heating the heat exchanger; a flow rate sensor (150) for measuring a flow rate of hot water in a flow passage passing the heating part; and a control part for controlling the water heater. The control part includes: an estimated flow rate value calculation part for calculating an estimated flow rate value in which a response lag of the flow rate sensor is corrected based on a measurement flow rate value by the flow rate sensor; and a combustion processing part for controlling the burner. In the case where the burner burns, when the estimated flow rate value is below a lowest operation flow rate and the measurement flow rate value is equal to or greater than the lowest operation flow rate, the combustion processing part controls the burner so as to continue combustion by generating predetermined heat quantity.SELECTED DRAWING: Figure 1

Description

  The present disclosure relates to a hot water supply apparatus and a control method for the hot water supply apparatus, and more particularly to a hot water supply apparatus that controls combustion based on a predicted flow rate and a control method for the hot water supply apparatus.

  Conventionally, a gas hot water supply device maintains the hot water temperature at a set temperature by measuring the flow rate of hot water in the hot water supply device and controlling the combustion of the gas burner based on the measured flow rate. However, when the flow rate fluctuates, it becomes difficult to stably maintain the set hot water temperature. This factor is mainly based on the detection signal of the flow sensor due to the inertia of the impeller even if the sampling period of the detection signal is excluded when the hot water flow rate is measured using an impeller type flow sensor or the like. This is because there is a delay in the flow rate recognized by the hot water supply apparatus, and as a result, there is a delay in the indication of the required number for controlling the gas burner. In this specification, in the hot water supply apparatus, the amount of heat (Kcal) generated by the combustion of the gas burner is indicated by “number”. The number = 1 corresponds to the amount of heat necessary to raise the hot water temperature by 25 ° C. under a flow rate of 1 (L / min).

  In order to deal with such a problem, Patent Document 1 (Japanese Patent Laid-Open No. 2014-137205) predicts a tapping temperature and controls combustion according to the predicted temperature. Moreover, in patent document 2 (Unexamined-Japanese-Patent No. 1-2247947), a flow rate is estimated and combustion is controlled based on a predicted flow rate.

JP 2014-137205 A JP-A-1-247947

  Since the flow rate predicting function generally includes a filter function as an amplifier, the predicted flow rate is calculated to be excessive compared to the actual flow rate. For example, when the hot water supply stop operation is performed, the predicted flow rate is calculated. Indicates a smaller value than the actual flow rate. If the required number is calculated based on such a predicted flow rate, the predicted flow rate becomes MOQ (minimum operating flow rate) or less at an early stage, and combustion stops. If the combustion is stopped early as described above, it is possible to prevent a situation in which hot water is discharged (overshoot from the set temperature) during the hot water supply start operation (combustion start) immediately afterward, but the predicted flow rate is MOQ. It takes time to reach the above, that is, the ignition of the burner is delayed and low temperature hot water (undershoot from the set temperature) can be caused. Therefore, in the case of controlling combustion based on the predicted flow rate, it has been desired to provide a function for preventing an undershoot of the tapping temperature.

  Therefore, an object of the present disclosure is to provide a hot water supply device and a control method for the hot water supply device that perform combustion control based on the predicted flow rate so as to achieve an appropriate hot water temperature.

  A hot water supply apparatus according to an aspect of the present disclosure includes a heating unit including a heat exchanger and a burner that heats the heat exchanger, a flow rate sensor that measures a flow rate of hot water in a flow path that passes through the heating unit, and a hot water supply apparatus. A control unit that controls, the control unit based on the measured flow value by the flow sensor, an estimated flow value calculation unit that calculates an estimated flow value corrected for response delay of the flow sensor, and a combustion for controlling the burner And a combustion processing unit that generates a predetermined amount of heat and burns when the estimated flow rate value is less than the minimum operating flow rate and the measured flow rate value is greater than or equal to the minimum operating flow rate when the burner burns. Control the burner to continue.

  Preferably, the combustion processing unit includes a heat amount determining unit that determines a heat amount for heating the heating unit, and the heat amount determining unit determines a minimum heat amount that can be generated by combustion of the burner as a predetermined heat amount.

  Preferably, the combustion processing unit includes a heat amount determining unit that determines a heat amount for heating the heating unit, and the heat amount determining unit determines the predetermined heat amount from the difference between the minimum operating flow rate and the tapping temperature and the incoming water temperature.

  Preferably, when the burner burns, the combustion processing unit further continues combustion of the burner according to a predetermined criterion when the estimated flow rate value is less than the minimum operation flow rate and the measured flow rate value is not less than the minimum operation flow rate. Determine whether to stop the combustion.

  Preferably, the hot water supply apparatus includes a plurality of burners, and the predetermined criterion is that the number of burners in a combustion state is equal to or greater than a threshold when the estimated flow rate value is less than the minimum operating flow rate and the measured flow rate value is equal to or greater than the minimum operating flow rate. The burner is stopped when the number of burners is equal to or greater than the threshold, and the burner is allowed to continue burning when the number of burners is less than the threshold.

  Preferably, the hot water supply device further includes a pipe connected to the hot water tap and a distribution valve for diverting a part of the total water supply amount to the hot water supply device to the pipe, and the opening degree of the distribution valve is relative to the total water supply amount. The ratio of the diverted flow to the piping is included, and the predetermined standard includes a criterion that the opening degree is equal to or greater than the threshold value. When the opening degree is equal to or greater than the threshold value, the burner is continuously burned. Stop burning.

  Preferably, the predetermined criterion includes a criterion that the ambient temperature of the hot water supply apparatus is equal to or higher than the threshold value, and the burner is stopped when the ambient temperature is equal to or higher than the threshold value, and the burner is continuously burned when the ambient temperature is lower than the threshold value .

  Preferably, the combustion processing unit includes a heat amount determining unit that determines a heat amount for heating the heating unit, and the heat amount determining unit has a measured flow rate value equal to or higher than the minimum operating flow rate and an estimated flow rate value when the burner burns. Means for determining one of the amount of heat acquired based on the measured flow rate value and the amount of heat acquired based on the estimated flow rate value as the amount of heat for heating the heating unit when the minimum operating flow rate is greater than or equal to the minimum flow rate; When the amount of heat acquired based on the measured flow value is equal to or greater than the amount of heat acquired based on the estimated flow value, the amount of heat acquired based on the estimated flow value is determined as the amount of heat for heating the heating unit.

  According to another aspect of the present disclosure, a method for controlling a hot water supply device is provided. The hot water supply apparatus includes a heat exchanger including a heat exchanger and a burner that heats the heat exchanger, and a flow rate sensor that measures a flow rate of hot water in a flow path that passes through the heater. In the control method, the estimated flow value calculated in the step of calculating the estimated flow value corrected for the response delay of the flow sensor based on the measured flow value of the flow sensor and the burner burns is the minimum operation. And a step of controlling the burner so as to generate a predetermined amount of heat and continue combustion when the measured flow rate value is less than the flow rate and the measured flow rate value is not less than the minimum operating flow rate.

  According to the present disclosure, when the burner burns, if the estimated flow rate value is less than the minimum operating flow rate and the measured flow rate value is greater than or equal to the minimum operating flow rate, the combustion is performed by generating a predetermined amount of heat without stopping the combustion. The burner is controlled to continue. Thereby, even if the combustion is stopped thereafter, undershooting of the hot water temperature can be prevented at the time of hot water.

1 is a schematic configuration diagram of a hot water supply device according to Embodiment 1. FIG. 3 is a block diagram schematically showing a functional configuration of a controller 300. FIG. It is a wave form diagram for demonstrating the example which correct | amended the response delay of the can body flow rate. It is a wave form diagram for demonstrating the example which correct | amended the response delay of the total flow volume. It is a figure explaining control of the gas burner 30 at the time of hot water supply stop operation which concerns on Embodiment 1. FIG. 4 is a graph schematically illustrating an example of data in a table 313 according to the first embodiment. 3 is a schematic process flowchart of combustion control in hot water supply stop operation according to Embodiment 1; 4 is a processing flowchart of heat quantity determination according to the first embodiment. 6 is a process flowchart of heat quantity determination according to the second embodiment. It is a figure explaining the reference | standard which judges the combustion continuation / stop in the condition 2 which concerns on Embodiment 2. FIG.

  Embodiments of the present disclosure will be described in detail with reference to the drawings. In the drawings, the same reference numerals denote the same or corresponding parts.

[Embodiment 1]
(Configuration of hot water supply system)
FIG. 1 is a schematic configuration diagram of a hot water supply apparatus according to an embodiment of the present invention. Referring to FIG. 1, hot water supply apparatus 100 includes a heating unit 20, a gas burner 30, a combustion can body (hereinafter also simply referred to as “can body”) 10 that houses heating unit 20, a blower fan 40, A water pipe 50, a bypass pipe 60, a hot water pipe 70, and a controller 300 are included. The heating unit 20 is a part that heats water to make hot water, and includes a primary heat exchanger 11 and a secondary heat exchanger 21.

  A bypass pipe 60 is disposed between the water inlet pipe 50 and the hot water outlet pipe 70. A distribution valve 80 for controlling the diversion to the bypass pipe 60 is connected to the water inlet pipe 50. Further, a temperature sensor 110 and a flow rate sensor 150 are arranged in the water intake pipe 50. The temperature sensor 110 detects the incoming water temperature Tw. Tap water or the like is supplied to the water intake pipe 50. Depending on the opening degree of the distribution valve 80, a part of the water supply amount is diverted from the water inlet pipe 50 to the bypass pipe 60. The ratio of the diversion to the total water supply amount is controlled according to the opening degree of the distribution valve 80.

  The water in the water intake pipe 50 is first preheated by the secondary heat exchanger 21 and then mainly heated in the primary heat exchanger 11. Hot water heated to a predetermined temperature by the primary heat exchanger 11 and the secondary heat exchanger 21 is discharged from a hot water discharge pipe 70.

  The outlet pipe 70 is connected to the bypass pipe 60 at the junction 75. Accordingly, the hot water supply device 100 supplies hot water having a proper temperature, which is a mixture of the high temperature hot water output from the can body 10 and the water from the bypass pipe 60, to a predetermined hot water supply location such as a hot water tap 190 in a kitchen or bathroom. The

  The outlet pipe 70 is provided with a flow rate adjusting valve 90 and temperature sensors 120 and 130. The temperature sensor 120 is disposed on the upstream side (can body side) of the outlet pipe 70 with the bypass pipe 60 and detects the output hot water temperature (hereinafter, can body temperature) from the can body 10. The temperature sensor 130 is provided on the downstream side (the hot water side) from the junction 75 and detects the hot water temperature Th after the water from the bypass pipe 60 is mixed. The flow rate adjusting valve 90 is provided to control the hot water flow rate.

  The fuel gas delivered from the gas burner 30 is mixed with the combustion air from the blower fan 40. When the air-fuel mixture is ignited by an ignition device (not shown), the fuel gas is burned and a flame is generated. The combustion heat generated by the flame from the gas burner 30 is given to the primary heat exchanger 11 and the secondary heat exchanger 21 in the can 10.

  The primary heat exchanger 11 heats incoming water by heat exchange by sensible heat (combustion heat) of the combustion gas by the gas burner 30. The secondary heat exchanger 21 heats the water passed by the latent heat of the combustion exhaust gas from the gas burner 30 by heat exchange. An exhaust path 15 for exhausting the exhaust gas after heat exchange is provided on the downstream side of the can body 10 in the flow direction of the combustion gas. Thus, in the can 10, the water supplied from the water inlet pipe 50 is heated by the primary heat exchanger 11 and the secondary heat exchanger 21 by the amount of heat generated by the combustion in the gas burner 30.

  In the gas supply pipe 31 to the gas burner 30, an original gas solenoid valve 32, a gas proportional valve 33, and capacity switching valves 35a to 35c are arranged. The original gas solenoid valve 32 has a function of turning on / off the supply of fuel gas to the gas burner 30. The gas flow rate of the gas supply pipe 31 is controlled according to the opening degree of the gas proportional valve 33.

  The controller 300 includes a CPU (Central Processing Unit) 301, an interface 302 that controls input / output with the outside, a timer 303, and a storage unit 304. CPU 301 receives an output signal (detection value) and a user operation from each sensor via interface 302 and generates a control command to each device in order to control the overall operation of hot water supply apparatus 100. Output via. The user operation includes an operation on / off command for hot water supply apparatus 100 and a set hot water temperature (Tr) command. The control command includes a heating command for controlling the combustion of the gas burner 30. The heating command includes an open command or a close command to the original gas solenoid valve 32 and an opening command to the gas proportional valve 33.

  Further, in the hot water supply device 100, heated water (temperature Tw + ΔT) from the can body 10 and non-heated water from the bypass pipe 60 are introduced from the flow rate adjustment valve 90 disposed downstream (on the side of the hot water) from the junction 75. Hot water mixed with (temperature Tw) is output.

  The controller 300 can control the flow rate Q (can flow rate) and the hot water flow rate from the hot water pipe 70 by controlling the opening degree of the flow rate adjustment valve 90. In the hot water supply apparatus 100 shown in FIG. 1, the flow rate Q is determined by the water supply pressure and the opening degree of the flow rate adjustment valve 90.

  The flow sensor 150 is disposed on the downstream side (can body side) of the distribution valve 80. Therefore, the flow rate Q detected by the flow rate sensor 150 indicates the flow rate (can body flow rate) passing through the heating unit 20 stored in the can body 10. The flow sensor 150 is typically constituted by an impeller-type flow sensor.

  When the operation command for hot water supply apparatus 100 is turned on, controller 300 turns on the combustion operation in can 10 in response to flow rate Q detected by flow rate sensor 150 exceeding the MOQ (minimum operating flow rate). When the combustion operation is turned on, the original gas solenoid valve 32 is opened, and the supply of fuel gas to the gas burner 30 is started.

  As understood from FIG. 1, the flow rate adjusting valve 90 is inserted and connected to a water passage that passes from the water inlet pipe 50 through the can body 10 to the hot water outlet pipe 70. The flow sensor 150 can detect the flow rate of “water” in the water passage. As shown in FIG. 1, the output flow rate from the flow rate adjustment valve 90 is also determined by the value detected by the flow rate sensor 150 using the diversion ratio determined by the opening degree of the distribution valve 80 even with the configuration in which the bypass pipe 60 is provided. Can be detected.

(Functional configuration of controller 300)
FIG. 2 is a block diagram schematically showing a functional configuration of the controller 300. 2 may be configured by a software program executed by the CPU 301, dedicated hardware (electronic circuit), or a combination of a software program and a circuit.

  Referring to FIG. 2, controller 300 includes a flow rate measurement value calculation unit 305, an estimated flow value calculation unit 306, a heat treatment unit 310, and a heating command unit 311. The heat treatment unit 310 performs a process for controlling the gas burner 30. Specifically, a heating stop determination function for stopping the combustion of the gas burner 30, a heating start determination function for starting the combustion of the gas burner 30, and a heat amount determination for determining the heat amount for heating the heating unit 20 Part 309. The heating command unit 311 generates and outputs a heating command based on the output from the heat processing unit 310.

  In the embodiment, the amount of heat for heating the heating unit 20 by the gas burner 30 corresponds to a “necessary number” described later. The amount of heat is generated by heat generation when the gas burner 30 burns. The gas burner 30 is supplied with a gas amount corresponding to the opening degree of the gas proportional valve 33 and burns, and the opening degree of the gas proportional valve 33 is variably adjusted by an opening degree command. Therefore, the amount of heat for heating the heating unit 20 can be changed according to the valve opening degree indicated by the opening degree command.

  The flow rate measurement value calculation unit 305 receives the output Sq of the flow rate sensor 150, refers to a map or the like, or uses an approximate expression to determine the rotational speed of the impeller as a flow rate measurement value y [n] (measured flow rate value). Equivalent). The flow rate measurement value calculation unit 305 periodically performs conversion in synchronization with the sampling cycle of the output of the flow sensor 150. For example, the measurement value y [n] is the measurement value of the current sampling, the previous sampling measurement value is y [n−1], and the next sampling measurement value is y [n + 1].

  The estimated flow value calculation unit 306 calculates an estimated flow value x [n] from the measured value y [n]. Specifically, the estimated flow value calculation unit 306 acquires the measurement value y [n] from the output signal of the flow sensor 150 every predetermined period, and the measurement value y [n] acquired this time and the measurement acquired last time. A deviation (y [n] -y [n-1]) from the value y [n-1] is calculated. Then, the estimated flow value calculation unit 306 adds the value obtained by multiplying the deviation by the coefficient β to the measured value y [n] acquired this time to calculate the estimated flow value x [n]. The coefficient β is a predetermined value based on the ratio of the time constant T of the response delay with respect to the actual flow rate of the measured value y [n] and the predetermined period Ts. These relationships are expressed by the following formulas.

x [n] = y [n] + β · (y [n] −y [n−1])
Note that the method of calculating the estimated flow rate value is not limited to the above method.

  In the combustion state, the heat quantity determination unit 309 searches the table 313 stored in the storage unit 304 in order to determine the heat quantity for heating the heating unit 20, and based on the search result, the gas proportional valve A current value for controlling the opening of 33 is determined. The table 313 stores a current value (unit: mA) to be supplied to the gas proportional valve 33 in association with a required number RW described later. The data of the table 313 is acquired by experiment.

  The heat quantity determination unit 309 searches the table 313 based on the required number RW, reads the associated current value from the table 313 based on the search result, and outputs the current value to the heating command unit 311.

  The heating command unit 311 supplies an opening degree command indicating the current value from the heat quantity determination unit 309 to the gas proportional valve 33. The gas proportional valve 33 is controlled to have an opening degree according to the current value of the opening degree command when the gas burner 30 is in a combustion state. Thereby, the water supplied from the inlet pipe 50 is heated by the primary heat exchanger 11 and the secondary heat exchanger 21 by the calorific value accompanying combustion of the gas burner 30 according to the opening degree.

  Further, the heating command unit 311 outputs a closing command to the original gas solenoid valve 32 based on the output from the heating processing unit 310 when the heating processing unit 310 determines that the heating is stopped. When the original gas solenoid valve 32 closes the valve in accordance with the close command, the gas supply to the gas burner 30 is cut off and the combustion state is shifted to the combustion stop. Further, the heating command unit 311 outputs an opening command to the original gas solenoid valve 32 based on the output from the heating processing unit 310 when the heating processing unit 310 determines to start heating. When the original gas solenoid valve 32 opens the valve in accordance with the opening command, gas supply to the gas burner 30 is started, and the combustion state is shifted from the combustion stop state.

  In the embodiment, regarding the determination of the heating start associated with the hot water supply start operation such as the opening operation of the hot water tap 190, as a background of the embodiment, when the user performs the hot water supply start operation, the hot water having a temperature lower than the set temperature is used. Is accustomed to coming out of the hot water tap 190 first. Therefore, in view of the fact that the response delay of the flow sensor 150 is allowed during the hot water supply start operation, the heat treatment unit 310 uses the measurement value y [n] by using the measurement value y [n] in determining the start of heating. Increases and the condition of (MOQ ≧ measured value y [n]) is satisfied, it is determined that heating is started. Note that the determination of the stop of heating accompanying the hot water supply stop operation such as the closing operation of the hot water tap 190 is performed when the condition of (measured value y [n] <MOQ) is satisfied, as will be described later.

(Relationship between measured value y [n] and estimated flow rate value x [n])
The relationship between the measured value y [n] calculated by the measured flow value calculation unit 305 and the estimated flow value x [n] calculated by the estimated flow value calculation unit 306 will be described in association with the operation of stopping the combustion of the gas burner 30. To do. FIG. 3 is a waveform diagram for explaining an example in which the response delay of the can flow rate is corrected. As shown in FIG. 1, the flow sensor 150 measures the flow rate passing through the heating unit 20 of the can body 10. The vertical axis of FIG. 3 shows the can flow rate, and the horizontal axis shows time. In this example, the results when the can body flow rate is 9 (L / min), the incoming water pressure is 200 (kPa), and the like are illustrated.

  At time t1, the true value of the flow rate changes from 9 (L / min) to 0 (L / min) in a stepped manner due to the hot water supply stop operation. In this case, the measured value y [n] becomes a true value at time t 2 due to the inertia of the flow sensor 150. The estimated flow rate value x [n] corrected for the response delay becomes a true value at time t2A earlier than time t2.

  Moreover, although the flow sensor 150 is provided in the water intake pipe 50 in order to measure the flow volume (can body flow volume) which passes the heating part 20, it may measure the flow volume which passes the bypass pipe 60. The total flow rate (total flow rate) of the can flow rate and the flow rate of the bypass pipe 60 may be measured. In order to detect the total flow rate, the position of the flow rate sensor 150 may be moved so as to be provided downstream from the junction 75.

  FIG. 4 is a waveform diagram for explaining an example in which the response delay of the total flow rate is corrected. In the case of FIG. 4 as well, in the case of the hot water supply stop operation, the estimated flow rate value x [n] corrected for the response delay is a true value at a time earlier than the measured value y [n]. It becomes.

  As shown in FIG. 4, the flow sensor 150 used for the heating control of the heating unit 20 may not directly detect the flow rate of water passing through the heating unit 20. It may be a flow rate sensor provided in a water passage (water inlet pipe 50, bypass pipe 60, hot water tap 190, etc.) in which the water flow rate increases or decreases as the flow rate of water passing through the heating unit 20 increases or decreases. Therefore, the freedom degree of arrangement | positioning of a flow sensor increases, and the freedom degree of design of a hot-water supply apparatus increases.

  3 and 4, the measured value y [n], which is an actually measured value, does not reach the true value even when the estimated flow rate value x [n] has almost reached the true value during the hot water supply stop operation. That is, it can be seen that hot water remains in the heating unit 20. Therefore, if the combustion of the gas burner 30 is stopped when (estimated flow rate value x [n] <MOQ), the amount of hot water remaining in the heating unit 20 at the time of the next hot water supply start operation or from the combustion stop Depending on the elapsed time and the like, an undershoot of the hot water temperature at the start of hot water supply tends to occur.

  In order to prevent the occurrence of this undershoot, in the embodiment, when a hot water supply stop operation is performed, the heat treatment unit 310 (even if the estimated flow rate value x [n] <MOQ) is satisfied ( If measured value y [n] ≧ MOQ), the gas burner 30 is controlled so as to continue the combustion without stopping the combustion. This control will be described with reference to FIG. FIG. 5 is a diagram for explaining the control of the gas burner 30 when the hot water supply stop operation according to the embodiment is performed.

(Concept of control of gas burner 30)
In FIG. 5, the vertical axis represents the can flow rate, and the horizontal axis represents the passage of time since the hot water supply stop operation was started. Further, the state of the gas burner 30 (combustion state / combustion stop) is schematically shown in association with the passage of time. For the sake of explanation, the elapsed time in FIG. 5 is divided into Condition 1, Condition 2, and Condition 3 according to the magnitude relationship among the measured value y [n], the estimated flow rate value x [n], and the MOQ. 5 may be the total flow rate described above.

  FIG. 6 is a graph schematically illustrating an example of data in the table 313 according to the first embodiment. FIG. 6 shows the relationship of the opening degree of the gas proportional valve 33 in relation to the number. Specifically, the vertical axis of the graph represents the opening of the gas proportional valve 33, that is, the current value to be supplied to the gas proportional valve 33, and the horizontal axis represents a number. The graph also shows the number of combustion stages (2, 3, 5, 8, 10) of the gas burner 30.

  For example, when the number of combustion stages is 10, the number is variable between M (j) and M (max), and the gas proportional valve 33 is changed to the numbers M (j) to M (max). It is variable in the range of the associated opening.

  In the first embodiment, first, when a hot water supply stop operation is performed, the calorific value determining unit 309 is necessary for controlling the gas burner 30 using both the estimated flow rate value x [n] and the measured value y [n]. The number RW is calculated. Further, the calorific value determination unit 309 calculates the actual number W according to the measured value y [n] and the predicted number W1 according to the estimated flow rate value x [n] in accordance with the following formula in order to calculate the required number RW. .

Real number W = Measured value y [n] × (Tapping temperature Th−Incoming water temperature Tw)
Predicted number W1 = Estimated flow rate value x [n] × (Tapping temperature Th−Incoming water temperature Tw)
Note that the method of determining the actual number W and the predicted number W1 is not limited to the method according to the above calculation formula, and the table includes a flow value (measured value y [n] or estimated flow value x [n]), tapping water. A method of searching by the temperature Th and the incoming water temperature Tw and reading the corresponding number (real number W or predicted number W1) from the table may be used.

  The heat treatment unit 310 satisfies each condition according to the magnitude relationship between the measured value y [n] from the measured flow value calculation unit 305, the estimated flow value x [n] from the estimated flow value calculation unit 306, and the MOQ. The necessary number RW is calculated as follows under each condition for which the establishment is determined.

<Condition 1: Measured value y [n] ≧ MOQ and estimated flow rate value x [n] ≧ MOQ>
When it is determined that the condition 1 is satisfied, the heat quantity determination unit 309 determines that the required number RW = W1 when (W ≧ W1), and determines that the required number RW = W when (W ≦ W1). The calorific value determination unit 309 reads the current value to be supplied to the gas burner 30 from the table 313 based on the determined required number RW, and the opening degree command indicating the read current value is proportional to the gas via the heating command unit 311. Output to the valve 33.

  For example, when Condition 1 is satisfied and the number of combustion stages of the gas burner 30 is 10, a number M (j corresponding to the number of combustion stages 10 is obtained by searching the table 313 in FIG. 6 based on the required number RW. )... M (k)... M (k), the current value associated with the number M (k) that matches the required number RW.

  Thereby, in the condition 1, the heat amount determination unit 309 determines one of W and W1 as the heat amount for heating the heating unit 20. Furthermore, when (W ≧ W1), the heat quantity determination unit 309 determines the number (W1) based on the estimated flow rate value x [n] as the heat quantity for heating. As a result, the gas burner 30 is controlled so that the opening of the gas proportional valve 33 is reduced so as to be the number (W1), but combustion is maintained. When (W ≦ W1), the opening of the gas proportional valve 33 is maintained so that the number (W) is based on the measured value y [n], and the combustion state of the gas burner 30 is maintained.

<Condition 2: Measured value y [n] ≧ MOQ and estimated flow rate value x [n] <MOQ>
When it is determined that the condition 3 is satisfied, the heat quantity determination unit 309 determines the required number RW to a predetermined value so that the gas burner 30 does not stop burning. Details of such “continuation of combustion at a predetermined number” will be described later.

<Condition 3: Measurement value y [n] <MOQ>
When it is determined that the condition 2 is satisfied, the heat processing unit 310 issues a close command to stop the combustion via the heating command unit 311 regardless of the estimated flow rate value x [n]. 32. Thus, the original gas solenoid valve 32 is fully closed, the gas supply to the gas burner 30 is shut off, and the combustion state is shifted to the combustion stop.

(Flowchart of control of gas burner 30)
FIG. 7 is a schematic process flowchart of combustion control in the hot water supply stop operation according to the first embodiment. FIG. 8 is a process flowchart of heat quantity determination according to the first embodiment. These flowcharts are stored in the storage unit 304 as programs. The CPU 301 implements processing by reading out and executing a program from the storage unit 304. The program of the flowchart in FIG. 7 is called from the main routine and executed at regular time intervals.

  Referring to FIG. 7, the flow rate measurement value calculation unit 305 acquires the measurement value y [n] from the flow sensor 150 (step S1). The CPU 301 compares the measurement value y [n−1] acquired last time with the measurement value y [n] acquired this time, and determines whether or not the flow rate is decreasing (step S2). That is, it is determined whether or not a hot water supply stop operation has been performed.

  If the CPU 301 determines that y [n] ≦ y [n−1] is satisfied based on the above comparison (YES in step S2), that is, if it is determined that the hot water supply stop operation has been performed, the process proceeds to step S3. The estimated flow value calculation unit 306 executes processing for calculating the estimated flow value x [n]. On the other hand, if CPU 301 determines that y [n] ≦ y [n−1] is not satisfied (NO in step S2), that is, if it is determined that the hot water supply stop operation has not been performed, the process proceeds to step S7. Control is returned to the main routine.

  In step S3, the estimated flow value calculation unit 306 calculates an estimated flow value x [n] from the measured value y [n] according to the calculation formula described above (step S3). Then, it progresses to the calorie | heat amount determination process of step S6.

  With reference to FIG. 8, the heat quantity determination process (step S6 in FIG. 7) will be described. First, the heat quantity determining unit 309 acquires the hot water temperature Th and the incoming water temperature Tw (step S61). And the calorie | heat amount determination part 309 is based on said hot water temperature Th and incoming water temperature Tw, the measured value y [n] calculated by step S1, and the estimated flow value x [n] calculated by step S3, and real number W and The predicted number W1 is calculated (step S63).

  The heat processing unit 310 determines which of condition 1, condition 2, and condition 3 shown in FIG. 5 is satisfied based on the measured value y [n], the estimated flow value x [n], and the MOQ (step) S65). When the condition 1 is satisfied (“condition 1” in step S67), the heat quantity determination unit 309, in step S69, <condition 1: measured value y [n] ≧ MOQ and estimated flow rate value x [n] ≧ MOQ> is executed. When the condition 2 is satisfied (“condition 2” in step S67), the heat quantity determination unit 309 determines in step S71 that the above <condition 2: measured value y [n] ≧ MOQ and the estimated flow rate value x [n ] <MOQ> "Continue combustion at a predetermined number" is performed. When the condition 3 is satisfied (“condition 3” in step S67), the heat treatment unit 310 performs a combustion stop process of <condition 3: measured value y [n] <MOQ> in step S73. . Thereafter, the process returns to the original process (step S6 in FIG. 6).

(Processing of “continuous combustion at the specified number”)
In condition 2, the process of “continuation of combustion at a predetermined number” is performed. In this process, the heat quantity determination unit 309 continues the combustion of the gas burner 30 with a predetermined number. For example, the predetermined number is determined to be the minimum number that is the minimum amount of heat that can be generated by the combustion of the gas burner 30 in the number of combustion stages when the condition 2 is satisfied. For example, when the number of combustion stages is 10 when the condition 2 is satisfied, the heat quantity determination unit 309 searches the table 313 in FIG. 6 and issues numbers M (j) to M (max) corresponding to the 10 combustion stages. ) Is read out and the number M (j) is determined as a predetermined number. Then, the heat quantity determining unit 309 searches the table 313 based on the number M (j) and reads the current value C1 associated with the number M (j) from the table 313. From the heating command unit 311, an opening command based on the current value C <b> 1 is output to the gas proportional valve 33. Thereby, in the condition 2, the gas burner 30 can continue a combustion state so that the heating part 20 may be heated with the calorie | heat amount of the minimum number of a combustion stage number. Although the number of combustion stages is 10 here, the predetermined number can be similarly determined even in other stages, and the combustion state of the gas burner 30 can be continued according to the determined predetermined number.

  As another method, in condition 2, the required number RW may be calculated using MOQ regardless of the estimated flow rate value x [n] and the measured value y [n]. For example, the combustion amount corresponding to the opening degree (current value) of the gas proportional valve 33 is calculated by calculating RW = MOQ × (tapping water temperature Th−incoming water temperature Tw) and searching the table 313 based on the calculated required number RW. Thus, the combustion state of the gas burner 30 may be continued. Further, the predetermined number may be a smaller one (or a larger one) of the above-mentioned minimum heat amount and RW = MOQ × (the hot water temperature Th−the incoming water temperature Tw), or an average value.

  According to the first embodiment described above, the hot water supply apparatus determines the required number RW according to the estimated flow rate value x [n], and when the hot water supply stop operation is performed (estimated flow rate value x [n] <MOQ) Even in such a case, since the combustion of the gas burner 30 can be continued, an undershoot of the tapping temperature during the subsequent hot water supply start operation can be prevented. In addition, since the combustion is continued according to the minimum number of the above combustion stages or the number according to the MOQ, the hot water temperature at the subsequent hot water supply starting operation becomes high (overheated hot water temperature). The situation can also be prevented.

[Embodiment 2]
The second embodiment shows a modification of the first embodiment. In the first embodiment, the “continuation of combustion at a predetermined number” is performed under the condition 2. However, in the second embodiment, the “continuation of combustion at the predetermined number” or the combustion is performed according to a predetermined standard in the condition 2. A determination is made to implement one of the stops.

  FIG. 9 is a process flowchart of heat quantity determination according to the second embodiment. In the flowchart of FIG. 9, Step S68 and Step S70 are added to the processing of “Condition 2” in the flowchart of FIG. 7, and only the additional processing will be described here. The other processes in FIG. 9 are the same as those in FIG. 7, and therefore description thereof will not be repeated.

  Referring to FIG. 9, when it is determined that “condition 2” is satisfied, heat treatment unit 310 determines whether to continue the combustion state of gas burner 30 or to stop combustion according to a predetermined standard (step S68). . Details of this determination will be described later. When the result of determination is that combustion is continued (“continuation” in step S70), the above-described “continuation of combustion at a predetermined number” is performed (step S71).

  On the other hand, when the result of determination is that combustion is stopped (“stop” in step S70), the heat treatment unit 310 performs combustion regardless of the estimated flow rate value x [n] and the measured value y [n]. In order to stop, a close command is output to the original gas solenoid valve 32 via the heating command unit 311. Thereby, the gas burner 30 shifts from the combustion state to the combustion stop (step S73). An example of the determination process in step S68 will be described below.

(Example of determining whether to continue or stop combustion)
In this example, the predetermined standard includes that the number of combustion stages of the gas burner 30 is equal to or greater than a threshold value. The heat processing unit 310 determines whether to continue combustion or stop combustion based on whether the number of combustion stages of the gas burner 30 is equal to or greater than a threshold value. FIG. 10 is a diagram for explaining a criterion for determining combustion continuation / stop in condition 2 according to the second embodiment. FIG. 10 shows a state where a plurality of pipes 111 and ten (10 stages) gas burners 30 in the primary heat exchanger 11 are arranged. The combustion stage number B2, the combustion stage number B3, the combustion stage number B5, the combustion stage number B7, and the combustion stage number B10 in FIG. .

  In step S <b> 68, the heat processing unit 310 determines whether to continue or stop combustion according to the number of combustion stages of the gas burner 30. For example, when the gas burner 30 when it is determined that the condition 2 is satisfied has the combustion stage number B10, all the pipes 111 are heated by the heat generated from the gas burner 30. As a result, the medium (hot water or the like) in the heating unit 20 can have a large amount of heat storage. Therefore, even if the gas burner 30 is stopped from burning under the condition 2, the temperature of the hot water in all the pipes 111 can be easily maintained, and a decrease (undershoot) in the hot water temperature during the subsequent hot water supply start operation can be prevented.

  On the other hand, when the gas burner 30 when it is determined that the condition 2 is satisfied is the combustion stage number B2, many pipes 111 are not heated, and a medium (hot water or the like) in the heating unit 20 is not heated. There is little heat storage. Therefore, when the combustion of the gas burner 30 is stopped under the condition 2, the temperature of the hot water in the pipe 111 is likely to decrease, and an undershoot of the hot water temperature at the time of the subsequent hot water supply start operation is likely to occur.

  Therefore, in step S68, the heat treatment unit 310 compares the number of combustion stages (combustion number) of the gas burner 30 with a threshold value, and determines that the combustion of the gas burner 30 is stopped when it is determined that (combustion stage number ≧ threshold value). Otherwise, it is determined that combustion is continued.

(Other examples of judgment of continuation / stop of combustion)
In this example, the predetermined reference includes that the opening degree of the distribution valve 80 is equal to or greater than a threshold value. The heat processing unit 310 determines whether to continue or stop combustion based on whether the opening of the distribution valve 80 is equal to or greater than a threshold value. The opening degree of the distribution valve 80 indicates the ratio of the diversion to the bypass pipe 60 with respect to the total water supply amount. When the proportion of the diversion is large, there is a high possibility that the hot water temperature from the hot water tap 190 is lowered (undershoot) due to a large amount of water supplied from the bypass pipe 60 during the hot water supply start operation. Therefore, in step S68, the heat treatment unit 310 compares the opening degree (distribution ratio) of the distribution valve 80 with a threshold value, and determines that (the opening degree of the distribution valve 80 ≧ threshold value), the combustion is continued. If not, it is determined that combustion has stopped.

(Still another example of judgment of combustion continuation / stop)
In this example, the predetermined reference includes that the ambient temperature of the hot water supply device 100 is equal to or higher than a threshold value. Heat processing unit 310 determines whether to continue or stop combustion based on whether or not the ambient temperature of hot water supply device 100 is equal to or higher than a threshold value. Specifically, when the ambient temperature is low, the possibility that an undershoot of the hot water temperature will occur at the subsequent hot water supply start operation is higher than when the temperature is high. As this ambient temperature, for example, an incoming water temperature Tw from a water supply or the like can be used. Therefore, in step S68, the heat treatment unit 310 compares the incoming water temperature Tw with a threshold value, and when it is determined that (incoming water temperature Tw <threshold value), it is determined that combustion is continued, and (incoming water temperature Tw ≧ threshold value). In some cases, it is determined that combustion has stopped.

  Note that the threshold values for determining the combustion continuation / stop described above can be obtained by experiments or the like. Further, the determination of combustion continuation / stop may be performed by combining two or more criteria (two or more criteria among the number of combustion stages, the distribution valve 80 fraction and the ambient temperature).

  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.

  20 Heating Unit, 30 Gas Burner, 32 Source Gas Solenoid Valve, 33 Gas Proportional Valve, 50 Water Inlet Pipe, 60 Bypass Pipe, 70 Hot Water Pipe, 75 Junction Point, 80 Distribution Valve, 90 Flow Control Valve, 100 Hot Water Supply Device, 110, 120 , 130 Temperature sensor, 111 Piping, 150 Flow rate sensor, 190 Hot water tap, 300 Controller, 305 Flow rate measurement value calculation unit, 306 Estimated flow value calculation unit, 309 Heat quantity determination unit, 310 Heat processing unit, 311 Heating command unit, 313 Table .

Claims (9)

A water heater,
A heating unit including a heat exchanger and a burner for heating the heat exchanger;
A flow rate sensor for measuring a flow rate of hot water in a flow path passing through the heating unit;
A controller for controlling the hot water supply device,
The controller is
An estimated flow value calculation unit that calculates an estimated flow value corrected for a response delay of the flow sensor based on a measured flow value by the flow sensor;
A combustion processing unit for controlling the burner,
The combustion processing unit
When the burner burns, if the estimated flow rate value is less than the minimum operating flow rate and the measured flow rate value is greater than or equal to the minimum operating flow rate, the burner is controlled to generate a predetermined amount of heat and continue combustion. A water heater. The combustion processing unit
A calorific value determining unit for determining a calorific value for heating the heating unit;
The calorific value determining unit
The hot water supply apparatus according to claim 1, wherein a minimum heat amount that can be generated by combustion of the burner is determined as the predetermined heat amount. The combustion processing unit
A calorific value determining unit for determining a calorific value for heating the heating unit;
The calorific value determining unit
The hot water supply apparatus according to claim 1 or 2, wherein the predetermined amount of heat is determined from a minimum operating flow rate and a difference between a hot water temperature and an incoming water temperature. The combustion processing unit further includes:
When the burner burns, if the estimated flow rate value is less than the minimum operating flow rate and the measured flow rate value is greater than or equal to the minimum operating flow rate, either the burner continues to burn or is stopped according to a predetermined standard. The hot-water supply apparatus of any one of Claim 1 to 3 which judges whether to do. The water heater is
Including a plurality of the burners;
The predetermined criterion includes a criterion that the number of burners in a combustion state is equal to or greater than a threshold when the estimated flow rate value is less than a minimum operating flow rate and the measured flow rate value is equal to or greater than a minimum operating flow rate,
The hot water supply device according to claim 4, wherein when the number of burners is equal to or greater than a threshold, the burner is stopped from burning, and when the number of burners is less than the threshold, the burner is continued to burn. The water heater is
Piping connected to the water tap,
A distribution valve for diverting a part of the total amount of water supplied to the hot water supply device to the pipe;
The opening degree of the distribution valve indicates a ratio of a diversion to the pipe with respect to the total water supply amount,
The predetermined criterion includes a criterion that the opening is equal to or greater than a threshold value,
The hot water supply device according to claim 4, wherein the burner is allowed to continue to burn when the opening degree is equal to or greater than a threshold value, and the combustion of the burner is stopped when the opening degree is less than the threshold value. The predetermined criterion includes a criterion that an ambient temperature of the hot water supply apparatus is equal to or higher than a threshold value,
The hot water supply device according to claim 4, wherein when the ambient temperature is equal to or higher than a threshold value, the burner is stopped from burning, and when the ambient temperature is lower than the threshold value, the burner is continued to burn. The combustion processing unit
A calorific value determining unit for determining a calorific value for heating the heating unit;
The calorific value determining unit
When the burner burns, when the measured flow rate value is equal to or higher than the minimum operating flow rate and the estimated flow rate value is equal to or higher than the minimum operating flow rate, based on the heat quantity acquired based on the measured flow rate value and the estimated flow rate value Means for determining one of the acquired heat quantities as a heat quantity for heating the heating unit;
The means for determining is
When the amount of heat acquired based on the measured flow value is equal to or greater than the amount of heat acquired based on the estimated flow value, the amount of heat acquired based on the estimated flow value is determined as the amount of heat for heating the heating unit. The hot water supply device according to any one of claims 1 to 7. A method for controlling a water heater,
The water heater is
A heating unit including a heat exchanger and a burner for heating the heat exchanger;
A flow rate sensor for measuring the flow rate of hot water in the flow path passing through the heating unit,
The control method is:
Calculating an estimated flow rate value obtained by correcting a response delay of the flow rate sensor based on a flow rate value measured by the flow rate sensor;
When the burner burns, if the estimated flow rate value calculated in the calculating step is less than the minimum operating flow rate and the measured flow rate value is greater than or equal to the minimum operating flow rate, a predetermined amount of heat is generated and combustion continues. A method of controlling the hot water supply device, comprising:

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