JP2017020702A - Hot water supply device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform an accurate correction of delay in response to an output from a flow sensor and improve a temperature stability when the hot water is outputted again after stopping of the hot water supply.SOLUTION: An estimated flow rate calculation part 304 gets a measured value y[n] from an output signal from a flow rate sensor for every prescribed period and a deviation [y[n]-y[n-1]] is calculated. Then, the estimated flow rate calculation part 304 adds a value multiplied to the deviation by a coefficient β to a measured value y[n] got at this time to calculate an estimated flow rate value x[n]. The coefficient β is a prescribed value on the basis of rate between a time constant T in delay in response to an actual flow rate of the measured value y[n] and a prescribed period Ts. The estimated flow rate value x[n] corrected the delay in response of a flow rate sensor 150 is applied for judgement about stoppage of heating operation, it is possible to shorten a fire extinction delay time. With this arrangement as above, stability in temperature at the time of restarting of hot water supply is increased.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a hot water supply apparatus, and more particularly to heating control of a heating unit based on an output of a flow sensor.

  In the hot water supply apparatus, feedback control using the hot water supply temperature is performed in order to supply hot water at an appropriate temperature. However, since it is necessary to change the heating amount according to the amount of hot water supply, it is desirable to use not only the hot water supply temperature but also the flow rate as a parameter for feedback control in order to perform accurate temperature control.

  In Japanese Patent Publication No. 7-15336 (Patent Document 1), in a simple water heater with reduced manufacturing cost, the amount of water is estimated based on the descending gradient of the detected temperature from the time of opening of the tapping temperature sensor, and heating is performed. It is described that the amount of heating is controlled according to the amount of water in the early period of the start. By this control, the rise of the hot water temperature can be accelerated.

Japanese Patent Publication No. 7-15336

  Conventionally, in a gas water heater, a fire extinguishing delay at the time of hot water supply stop can be cited as a factor that deteriorates temperature stability at the time of re-heating after hot water supply stop. The main cause of this fire-extinguishing delay is that, in the impeller-type flow sensor for detecting the amount of water flow, the impeller continues to rotate for a while due to inertia even after the water flow has stopped. Is delayed.

  If the fire-extinguishing delay time at the time of hot water supply stop is long, the water staying in the water heater continues to be heated even after the stopper is stopped, and the temperature rapidly rises and may greatly exceed the set temperature. Since this hot water may be discharged from the hot water tap when re-watering, it is desirable to stop heating as quickly as possible when hot water is stopped.

  The present invention has been made to solve such problems, and an object of the present invention is to accurately correct the response delay of the output of the flow sensor and to stabilize the temperature at the time of re-watering after stopping hot water supply. It is to improve.

  A hot water supply device according to the present invention receives a heating unit that heats water, a flow rate sensor that detects a flow rate of a water passage that changes flow rate according to a change in the amount of water that passes through the heating unit, and an output signal of the flow rate sensor. And a control device that calculates an estimated flow rate value in which a response delay of the flow rate sensor is corrected, and performs control for switching the heating unit from the heating state to the heating stop state based on the estimated flow rate value. The control device acquires a measurement value from the output signal of the flow rate sensor every predetermined period, and multiplies the difference between the measurement value acquired this time and the measurement value acquired last time by a coefficient to the measurement value acquired this time. The estimated flow value is calculated by adding the values. The above coefficient is a value determined in advance based on the ratio between the time constant of the response delay of the measured value with respect to the actual flow rate and the predetermined period.

  According to the hot water supply device, based on the estimated flow rate value obtained by correcting the response delay of the flow rate sensor, it is determined that the water supply to the heating unit has been stopped, and the heating unit is set in a heating stopped state. For this reason, when the user performs a hot water supply stop operation, the heating of the hot water in the heating unit is quickly stopped, so that the temperature of the hot water staying in the heating unit can be prevented from rising rapidly. Therefore, it is possible to mitigate that the hot water temperature is excessively higher than the set temperature when hot water supply is resumed.

  Preferably, the control device, based on the estimated flow rate value, based on the measurement value acquired from the heating stop determination unit that performs the determination to shift the heating unit from the heating state to the heating stop state, and the output signal of the flow sensor, A heating start determination unit that performs determination to shift the heating unit from the heating stop state to the heating state.

  The user is not accustomed to hot water having a temperature higher than the set temperature coming out of the hot water tap first. Since the control device is configured as described above, the response delay of the flow rate sensor is corrected during the hot water supply stop operation, and an excessive increase in the temperature of the hot water remaining in the heating unit can be suppressed. However, the process for correcting the response delay may become unstable due to vibration of the estimated flow rate. On the other hand, the user is accustomed to hot water having a temperature lower than the set temperature coming out of the hot water tap first when the hot water supply start operation is performed. Accordingly, since a drop in hot water temperature due to a response delay of the flow rate sensor is allowed during a hot water supply resuming operation, a stable heating start determination can be made by using the measured value as it is during a hot water supply resuming operation.

  More preferably, when j is a natural number of 1 or more and k is a natural number greater than j, the heating start determination unit has a measured value within a predetermined time after heating of the heating unit is stopped by the heating stop determination unit. When the heating start determination value is exceeded j times, the heating unit is shifted to a heating state, and the heating start determination unit has a measured value k after a predetermined time after heating of the heating unit is stopped by the heating stop determination unit. When the heating start determination value is exceeded continuously for a number of times, the heating unit is shifted to the heating state.

  As described above, the process of correcting the response delay may become unstable due to the flow rate estimation value oscillating. Therefore, there is a possibility that the heating stop determination unit stops heating by mistake. In this case, the hot water temperature is suddenly lowered, which causes inconvenience to the user. Therefore, when the heating is stopped by the estimated flow rate value, in preparation for an erroneous determination within a predetermined time, immediately after the measured value of the flow sensor exceeds the heating start determination value, heating in the heating unit is resumed to reduce the hot water temperature. Reduce as much as possible. On the other hand, even when heating is stopped by the estimated flow rate, if the measured value of the flow sensor does not exceed the heating start determination value even after a predetermined time has passed, the possibility that heating has been stopped due to an erroneous determination is reduced. . Therefore, at this time, the malfunction of the heating unit is avoided by carefully determining the start of heating.

  Preferably, the hot water supply apparatus further includes a water inlet pipe for supplying water to the heating unit, a hot water outlet pipe for discharging hot water from the heating part, and a bypass passage branched from the water inlet pipe and joined to the hot water outlet pipe. The flow sensor detects one of a first flow rate that passes through the heating unit, a second flow rate that passes through the bypass passage, and a total flow rate of the first flow rate and the second flow rate.

  The flow rate sensor used for heating control of the heating unit may not directly detect the flow rate of water passing through the heating unit, and is provided in a water passage that increases or decreases as the flow rate of water passing through the heating unit increases or decreases. It may be a flow sensor. 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.

  According to the present invention, since the response delay in the output of the flow sensor is corrected with high accuracy, the heating in the heating unit is immediately stopped when hot water supply is stopped, so that the temperature stability during re-heating is improved.

It is a schematic block diagram of the hot water supply apparatus according to embodiment of this invention. It is the wave form diagram which showed the difference of the detected value of the flow sensor 150 at the time of water flow stop, and an actual flow volume. It is a wave form diagram for explaining the temperature rise in the heating part in the can at the time of resuming hot water supply in the examination example. 2 is a block diagram showing a configuration of a controller 300. FIG. It is a flowchart explaining the content of the flow volume estimation process and the heating stop process which the controller 300 performs. It is a wave form chart for explaining the example which corrected the response delay of the can flow rate, and shortened the fire extinguishing delay at the time of closure. It is a wave form chart for explaining the example which correct | amended the response delay of the total flow volume, and shortened the fire-extinguishing delay at the time of closure. It is a flowchart explaining the content of the heating start process which the controller 300 performs.

  Embodiments of the present invention will be described below 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 configuration diagram of a hot water supply apparatus according to an embodiment of the present invention. Referring to FIG. 1, a hot water supply device 100 includes a heating unit 20, a combustion can body (hereinafter simply referred to as “can body”) 10 that houses the heating unit 20, a blower fan 40, a water inlet pipe 50, A bypass pipe 60, a hot water outlet pipe 70, and a controller 300 are included. The heating unit 20 is a part that heats water into hot water, and includes a primary heat exchanger 11, a secondary heat exchanger 21, and a gas burner 30.

  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, hot water having a proper temperature obtained by mixing the hot water output from the can 10 and the water from the bypass pipe 60 from the hot water supply device 100 is poured into a hot water tap 190 such as a kitchen and a bathroom and a bath (not shown). It is supplied to a predetermined hot water supply location such as a circuit.

  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.

  In the can 10, 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.

  Controller 300 receives an output signal (detected value) from each sensor and a user operation, and generates a control command to each device in order to control the overall operation of hot water supply apparatus 100. 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 opening / closing and opening command of each valve, and an electrical input command (fan drive voltage command) to the blower fan 40.

  In the hot water supply apparatus 100, heated water (temperature Tw + ΔT) from the can body 10 and non-heated water (temperature) from the bypass pipe 60 are disposed from the flow rate adjustment valve 90 disposed on the downstream side (outlet side) from the junction 75. The hot water mixed with 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 shown in FIG. 1, the flow rate Q is determined by the feed water 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 the hot water supply device 100 is turned on, the controller 300 turns on the combustion operation in the can body 10 in response to the flow rate Q detected by the flow rate sensor 150 exceeding the minimum operating flow rate (MOQ). 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.

  As described above, the detected value of the flow sensor 150 used for the on / off control of the combustion operation is that the impeller continues to rotate for a while due to the inertia even after the water flow is stopped, so that the actual flow rate decreases with respect to the output signal. Reflection may be delayed.

  FIG. 2 is a waveform diagram showing the difference between the detected value of the flow sensor 150 and the actual flow rate when water flow is stopped. Referring to FIG. 2, the flow rate (true value) of inlet pipe 50 is reduced from 9 (L / min) to zero as the user performs hot water supply stop operation at time t1. However, due to the inertia of the impeller, the measured value of the flow sensor 150 does not reach the minimum operating flow rate MOQ until time t2. Therefore, the fire extinguishing of the gas burner 30 in the heating unit 20 is delayed between the times t1 and t2. This fire extinguishing delay period reaches, for example, 1 (sec).

  About the examination example assumed that this fire-extinguishing delay will generate | occur | produce in the heating part 20 as it is, the influence of the fire-extinguishing delay at the time of hot water supply restart is demonstrated. FIG. 3 is a waveform diagram for explaining a temperature rise in the heating part in the can when restarting hot water supply in the examination example.

  Referring to FIG. 3, flow rate Qt indicates the flow rate of the can body, temperature T1 indicates the temperature detected by temperature sensor 120 (can body thermistor), and temperature T2 indicates temperature sensor 130 provided in the tapping pipe. The temperature T3 indicates the temperature detected at the hot water tap 190 5 m ahead of the hot water supply device 100.

  Prior to time t10, the hot water supply apparatus is operated to stop hot water supply, and the flow rate Qt is once zero. If a fire extinguishing delay has occurred at this time, the hot water is heated in a state where it stays in the heating unit 20 due to the fire extinguishing delay, and becomes hot water. When the hot water supply restarting operation is performed at time t11, the high-temperature hot water retained in the heating unit 20 comes out from the can 10 to the installation portion of the temperature sensor 120 as indicated by the peak P1 at time t12. Thereafter, the cold water from the bypass pipe 60 is mixed and the peak temperature is lowered at the time t13. However, a portion exceeding the target temperature remains at the hot water tap 190 as indicated by the peak P2 at the time t14.

  In the present embodiment, the controller 300 corrects and uses the flow sensor 150 in order to eliminate the instability of the hot water supply temperature when resuming the hot water supply as described above. Hereinafter, the configuration and operation of the controller 300 will be described.

  The controller 300 receives the output signal of the flow sensor 150, calculates an estimated flow value that corrects the response delay of the flow sensor, and performs control to switch the heating unit from the heating state to the heating stopped state based on the estimated flow value.

  According to the hot water supply apparatus according to the present embodiment, based on the estimated flow rate value obtained by correcting the response delay of the flow rate sensor 150, it is determined that the water supply to the heating unit 20 has been stopped, and the heating unit 20 is in a heating stopped state. And For this reason, when the user performs a hot water supply stop operation, the heating of water in the heating unit 20 is quickly stopped, so that the temperature of the hot water staying in the heating unit 20 can be prevented from rising rapidly. Therefore, it is possible to mitigate that the hot water temperature is excessively higher than the set temperature when hot water supply is resumed.

  FIG. 4 is a block diagram showing the configuration of the controller 300. The controller 300 includes a CPU, a storage device, an input / output buffer and the like (all not shown), receives signals from various sensors and devices, and controls the heating unit 20. This control is not limited to processing by software, and processing by dedicated hardware (electronic circuit) is also possible.

  Referring to FIG. 4, controller 300 includes a flow rate measurement value calculation unit 302, an estimated flow value calculation unit 304, a heating stop determination unit 306, a heating start determination unit 308, and a heating command generation unit 310.

  The flow rate measurement value calculation unit 302 receives the output Sq of the flow rate sensor 150, refers to a map or the like, or uses an approximate expression to convert the rotational speed of the impeller to a flow rate measurement value y [n]. Note that the flow rate measurement value calculation unit 302 periodically performs conversion, and n is an integer that increases as the number of measurements increases. For example, the measurement value y [n] is the current measurement value, the previous measurement value is y [n−1], and the next measurement value is y [n + 1].

  The estimated flow value calculation unit 304 executes processing for calculating an estimated flow value x [n] from the measured value y [n].

The estimated flow value calculation unit 304 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 value y [n− acquired last time. 1] (y [n] -y [n-1]) is calculated. Then, the estimated flow value calculation unit 304 adds a value obtained by multiplying the deviation by a coefficient β to the measured value y [n] acquired this time to calculate the estimated flow value x [n]. The coefficient β is a value determined in advance based on the ratio between 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 T _s . These relationships are expressed by the following formulas. The derivation of this mathematical formula will be described later.

x [n] = y [n] + β · (y [n] −y [n−1])
The heating stop determination unit 306 determines to shift the heating unit from the heating state to the heating stop state based on the estimated flow rate value x [n]. On the other hand, the heating start determination unit 308 determines to shift the heating unit from the heating stop state to the heating state based on the measurement value y [n]. When the heating stop determination unit 306 determines the heating stop, the heating command generation unit 310 outputs a command to stop the heating of the heating unit 20, and the heating start determination unit 308 determines the heating start. Sometimes, a command to start heating of the heating unit 20 is output.

  The user is not accustomed to the fact that hot water having a temperature higher than the set temperature first comes out of the hot water tap when the hot water supply start operation is performed. Therefore, at the time of hot water supply stop operation, the response delay of the flow sensor 150 is corrected by the estimated flow value calculation unit 304, and the excessive increase in the temperature of the hot water retained in the heating unit 20 is suppressed by the heating stop determination unit 306.

  However, the process for correcting the response delay may become unstable due to vibration of the flow rate estimated value x [n]. On the other hand, the user is accustomed to the fact that when a hot water supply start operation is performed, hot water having a temperature lower than the set temperature first comes out of the hot water tap. Therefore, in consideration of the fact that the response delay of the flow sensor 150 is allowed during the hot water supply resuming operation, the heating start determination unit 308 makes a stable heating start determination by using the measured value y [n] as it is. Hereinafter, details of the heating stop determination process and the heating start determination process will be described in order.

[Explanation of heat stop process]
FIG. 5 is a flowchart for explaining the contents of the flow rate estimation process and the heating stop process performed by the controller 300. The process of this flowchart is called from the main routine and executed at regular intervals.

  With reference to FIG. 5, the controller 300 acquires the measured value y [n] from the flow sensor 150 in step S1. Subsequently, the controller 300 compares the measurement value y [n−1] acquired last time in step S2 with the measurement value y [n] acquired this time, and determines whether or not the flow rate is decreasing.

  If y [n] ≦ y [n−1] is satisfied in step S2 (YES in S2), the process proceeds to step S3 to execute the process of estimating the flow rate x [n], while y [n] If n] ≦ y [n−1] is not satisfied (NO in S2), the process proceeds to step S7, and the control is returned to the main routine.

  In step S3, the controller 300 estimates the flow rate x [n] from the measured value y [n]. At this time, the flow rate x [n] is calculated based on the mathematical expression x [n] = y [n] + β · (y [n] −y [n−1]). Derivation of this mathematical expression will be described.

  Assume that the actual flow rate at time t is x (t) and t = 0 when the plug is closed. At this time, the flow rate change at the time of closing is a step input expressed by the following equations (1) and (2).

  The response of the flow rate y (t) calculated from the rotational speed of the flow rate sensor 150 to the step input is assumed to be a temporary delay, and the time constant is T. The flow rate y (t) is expressed by the following equation (3).

  When the sampling cycle of the flow rate y (t) is Ts and the discrete systems y [n−1] and y [n] are expressed by the above equation (3), the following equations (4) and (5) are obtained, and from these: Relational expression (6) is obtained.

Here, when X _∞ estimated at time [n] is expressed as X _∞ [n], the following equation (7) is obtained.

  When the equation (7) is further modified using α represented by the following equation (9), the following equation (8) is obtained.

  Furthermore, α is expressed by the following equation (10) by applying a first-order / first-order Pad approximation in which e-Ts / T is expanded around X = 0 (equation (8) is the same as above).

  If the equation is modified using β (= α + 1), the following equations (11) and (12) are obtained.

  When formula (11) is wrapped with β, formula (13) is obtained.

  Thus, the mathematical formula used in step S3 is derived. By this equation, the input x [n] can be estimated from the current output y [n] obtained at every sampling period Ts and the previous output y [n−1] one sampling before. The estimated input x [n] is compared with the minimum operating flow rate (MOQ) in steps S4 and S5, and used to determine whether to stop heating.

  Specifically, in step S4, it is determined that the currently estimated input x [n] is lower than the MOQ (YES in S4), and in step S5, the input a [x] n times a [x] is continuously higher than the MOQ. If it is determined that the temperature is small (YES in S5), stop heating is instructed in step S6, and then the process proceeds to step S7.

  If x [n] is not yet lower than the MOQ in step S4 (NO in S4), or if x [n] <MOQ has not been satisfied a number of times in the past in step S5 (in S5) If NO, the process of step S6 is not executed, and the process proceeds to step S7.

  Next, in the hot water supply apparatus of the present embodiment, the fire extinguishing delay shortening time by using the estimated value obtained by correcting the response delay of the flow sensor 150 will be described. FIG. 6 is a waveform diagram for explaining an example in which the response delay of the can flow rate is corrected and the fire-extinguishing delay at the time of closing is shortened. As shown in FIG. 1, the flow sensor 150 measures the flow rate passing through the heating unit 20 of the can body 10. For this reason, the vertical axis of FIG. 6 shows the can body 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), the time constant T = 0.4, and the number of detections a = 3 are shown.

  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. When the measurement value y [n] of the flow rate sensor is compared with the MOQ to determine whether to stop heating (comparative example), the fire is extinguished at time t2. On the other hand, when the heating stop determination is made by comparing the estimated value x [n] with the response delay corrected and the MOQ (embodiment), the fire is extinguished at time t2A. In this case, the fire delay time was reduced from about 1.0 seconds to about 0.5 seconds.

  The hot water supply apparatus 100 further includes a water inlet pipe 50 that supplies water to the heating unit, a hot water outlet pipe 70 that discharges hot water from the heating part, and a bypass pipe 60 that branches from the water inlet pipe 50 and joins the hot water outlet pipe 70. ing. The flow sensor 150 is provided in the water inlet pipe 50 in order to measure the flow rate (can body flow rate) passing through the heating unit 20, but the flow rate sensor 150 may measure the flow rate passing through the bypass pipe 60. The total flow rate (total flow rate) of the body 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. 7 is a waveform diagram for explaining an example in which the response delay of the total flow rate is corrected and the fire-extinguishing delay at the time of closing is shortened. As shown in FIG. 7, the total flow rate 14 (L / min) flows from time t20 to t21. At time t21, the true value of the flow rate is changed from 14 (L / min) to 0 (L / min) by the hot water supply stop operation. min) in steps. In the case where the measurement value y [n] of the flow rate sensor is compared with the MOQ to determine whether to stop heating (comparative example), the fire is extinguished at time t22. On the other hand, when the heating stop determination is made by comparing the estimated value x [n] with the response delay corrected and the MOQ (embodiment), the fire is extinguished at time t22A. In the case of FIG. 7 as well, in the case of FIG. 6, the fire delay time was reduced from about 1.0 seconds to about 0.5 seconds.

  As shown in FIG. 7, the flow rate sensor 150 used for 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.

  As described above, the hot water supply apparatus 100 of the present embodiment can shorten the fire extinguishing delay time by using the estimated value obtained by correcting the response delay of the flow sensor 150 for the heating stop determination. This increases the temperature stability when resuming hot water supply.

[Explanation of heat resumption process]
The processing for correcting the response delay in FIGS. 6 and 7 is preferable in terms of shortening the fire extinguishing delay, but the flow rate estimated value x [n] may oscillate and become unstable. Therefore, there is a possibility that the heating stop determination unit 306 in FIG. 4 stops heating by mistake. In this case, the temperature of the hot water is suddenly lowered, which is inconvenient for the user.

  Therefore, in the present embodiment, when the heating is stopped by the estimated flow rate x [n], the heating resumption time is shortened in preparation for an erroneous determination within a predetermined time. Specifically, when the measured value y [n] of the flow sensor 150 exceeds the heating start determination value (MOQ), the heating in the heating unit 20 is immediately resumed to reduce the decrease in hot water temperature as much as possible. On the other hand, even when the heating is stopped by the estimated flow rate value x [n], if the measured value y [n] of the flow rate sensor 150 does not exceed the heating start determination value even after a predetermined time has elapsed, the heating is performed by erroneous determination. Is less likely to have been stopped. Therefore, in this case, the determination of the heating start is carefully performed (for example, the measurement value y [n] is not started unless the measured value y [n] exceeds the heating start determination value), thereby avoiding malfunction of the heating unit. .

  For such processing, the controller 300 shown in FIG. 4 performs the following processing. In the heating start determination unit 308 of the controller 300, the measured value y [n] exceeds the heating start determination value j times within a predetermined time (T seconds) after heating of the heating unit is stopped by the heating stop determination unit 306. In this case, the heating unit 20 is shifted to a heating state. The heating start determination unit 308 determines the heating start determination value by continuously measuring the value y [n] k times after a predetermined time (T seconds) after the heating stop determination unit 306 stops the heating of the heating unit 20. When it exceeds, a heating part is changed to a heating state. In the above, j is a natural number of 1 or more, and k is a natural number larger than j.

  Hereinafter, an example in which j = 1 and k = a + 1 will be described with reference to flowcharts. However, k and j are not limited to these values, and can be changed to appropriate numerical values. FIG. 8 is a flowchart for explaining the contents of the heating start process performed by the controller 300. The process of this flowchart is called from the main routine and executed at regular intervals.

  Referring to FIG. 8, controller 300 determines whether or not estimated flow rate value x [n] falls below MOQ in step S11 and is within T (seconds) after heating is stopped. If it is within T (seconds) (YES in S11), the process proceeds to step S13 in preparation for an error in stopping heating.

  In step S13, the controller 300 determines whether or not the measured value y [n] from the flow sensor 150 exceeds the MOQ. If y [n]> MOQ is satisfied in step S13 (YES in S13), the process proceeds to step S14, and heating by the heating unit 20 is immediately resumed. On the other hand, if y [n]> MOQ does not hold in step S13 (NO in S13), the process of step S14 is not performed, and the control is returned to the main routine in step S15.

  On the other hand, if T (seconds) has elapsed in step S11 (NO in S11), it is unlikely that the heating stop was in error, so the process proceeds to step S12 so as to carefully resume heating. It is done. In step S12, it is determined whether or not the measured value y [n] has exceeded the MOQ for a predetermined number of times (a + 1) continuously. In step S12, when y [n]> MOQ is continuously established a predetermined number of times (YES in S12), the process proceeds to step S14, and heating by the heating unit 20 is started. On the other hand, if y [n]> MOQ does not hold continuously a predetermined number of times in step S12 (NO in S12), the process returns to the main routine in step S15 without performing the process in step S14.

  As described above, by performing the process, when the heating stop determination is performed using the estimated flow rate value x [n], even if the heating is erroneously stopped, the heating is immediately restarted. The decrease in hot water temperature can be kept small.

  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.

  DESCRIPTION OF SYMBOLS 10 Can body, 11 Primary heat exchanger, 15 Exhaust path, 20 Heating part, 21 Secondary heat exchanger, 30 Gas burner, 31 Gas supply pipe, 32 Original gas solenoid valve, 33 Gas proportional valve, 35a-35c Capacity switching valve , 40 Blower fan, 50 Water inlet pipe, 60 Bypass pipe, 70 Hot water outlet pipe, 75 Junction point, 80 Distribution valve, 90 Flow rate adjustment valve, 100 Hot water supply device, 110, 120, 130 Temperature sensor, 150 Flow rate sensor, 190 Hot water tap, 300 controller 302 measured flow value calculation unit 304 estimated flow value calculation unit 306 heating stop determination unit 308 heating start determination unit 310 heating command generation unit

Claims (4)

A heating section for heating water;
A flow rate sensor for detecting a flow rate of a water passage in which the flow rate changes according to a change in the amount of water passing through the heating unit;
A control device that receives an output signal of the flow sensor, calculates an estimated flow value that corrects a response delay of the flow sensor, and performs control for switching the heating unit from a heating state to a heating stop state based on the estimated flow value; With
The controller is
The measured value is acquired from the output signal of the flow rate sensor at predetermined intervals, and the value obtained by multiplying the deviation between the measured value acquired this time and the previously acquired measured value by the coefficient is added to the currently acquired measured value. And calculating the estimated flow rate value,
The said coefficient is a hot water supply apparatus which is a value previously determined based on the ratio of the time constant of the response delay with respect to the actual flow volume of the said measured value, and the said predetermined period. The controller is
Based on the estimated flow value, a heating stop determination unit that performs a determination to shift the heating unit from a heating state to a heating stop state;
The hot-water supply apparatus of Claim 1 containing the heating start determination part which performs the determination which transfers the said heating part from a heating stop state to a heating state based on the said measured value. If j is a natural number of 1 or more and k is a natural number larger than j,
The heating start determination unit sets the heating unit to a heated state when the measured value exceeds the heating start determination value j times within a predetermined time after heating of the heating unit is stopped by the heating stop determination unit. Migrate,
The heating start determination unit is configured to perform the heating when the measured value exceeds the heating start determination value continuously k times after the predetermined time since the heating stop determination unit stopped heating the heating unit. The hot-water supply apparatus of Claim 2 which makes a part transfer to a heating state. A water intake pipe for supplying water to the heating unit;
A tapping pipe for tapping hot water from the heating section;
A bypass passage that branches off from the water inlet pipe and joins the hot water outlet pipe,
The flow sensor detects one of a first flow rate that passes through the heating unit, a second flow rate that passes through the bypass passage, and a total flow rate of the first flow rate and the second flow rate. The hot water supply device according to any one of claims 1 to 3.

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