JP2009174787A - Hot water supply system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide technology capable of quickly stabilizing a hot water supply temperature at a desired temperature in feedback control of a mixing unit. <P>SOLUTION: A hot water supply system comprises: a hot water storage tank; a water supply passage for supplying water to the hot water storage tank; a hot water supply passage for supplying hot water from the hot water storage tank; a bypass passage as a mixing unit for adjusting a temperature by mixing the water in the water supply passage to the hot water in the hot water supply passage, and branched from the water supply passage and joined to the hot water supply passage while bypassing the hot water storage tank; the mixing unit disposed in the bypass passage and comprising a mixing valve; and a controller for adjusting an opening of the mixing valve. In this hot water supply system, the controller decides the increase and decrease of the opening of the mixing valve on the basis of not only a target mixing ratio and a present mixing ratio in the mixing unit but also a hot water supply flow. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a hot water storage type hot water supply system.

  The hot water storage type hot water supply system stores heated hot water in a hot water storage tank, and supplies hot water stored in the hot water storage tank as needed. Such a hot water supply system is employed in, for example, a cogeneration system that uses generated heat generated by power generation as a heat source for hot water supply. In the hot water storage type hot water supply system, when the temperature of the hot water stored is higher than the temperature of the hot water to be supplied, the hot water and water are mixed using a mixing unit and adjusted to the desired temperature before hot water supply. To do.

  In the hot water storage type hot water supply system, the mixing unit branches from a water supply path that supplies tap water to the lower part of the hot water tank and joins the hot water supply path that supplies hot water from the upper part of the hot water tank, and the water supply path and bypass The mixing valve provided in the branch part of a path | route or the junction part of a hot water supply path | route and a bypass path | route is provided. Hereinafter, a route from the water supply route through the hot water storage tank to the hot water supply route is referred to as a hot water side route, and a route from the water supply route through the bypass route to the hot water supply route is referred to as a water side route. The opening degree of the mixing valve can be adjusted, and the mixing ratio of hot water and water is adjusted by changing the opening degree. In such a hot water supply system, the opening of the mixing valve is adjusted so that the hot water supply temperature becomes a desired temperature based on the detection values of the thermistors provided in the water supply path and the hot water supply paths.

  In order to quickly supply hot water at a stable temperature, it is necessary to quickly adjust the temperature in the mixing unit by reducing the control delay in adjusting the opening of the mixing valve. Patent Document 1 discloses a technique in which feed-forward control and feedback control are combined to quickly adjust the temperature in a mixing unit and quickly supply hot water at a stable temperature.

Japanese Patent Laid-Open No. 7-190483

  The mixing ratio of hot water and water in the mixing unit varies depending on the hot water flow rate after mixing the hot water and water, even if the mixing valve is maintained at a predetermined opening. This is because the water side path passes through the bypass path, while the hot water side path passes through the hot water storage tank, so that the pressure loss characteristics are greatly different between the water side path and the hot water side path. Even if the mixing valve is maintained at a predetermined opening, when the hot water supply flow rate is reduced, water in the water-side path flows, but hot water in the hot-side path does not flow so much and the mixing ratio of water to hot water increases. Conversely, when the hot water supply flow rate increases, not only the water in the water-side path but also the hot water in the hot-water path flows, and as a result, the mixing ratio of water to the hot water decreases. In the mixing unit, the mixing ratio of water to hot water cannot be directly controlled, and the mixing ratio of water to hot water is indirectly controlled by adjusting the opening of the mixing valve. Therefore, hot water cannot be supplied at a desired temperature unless the influence of the hot water flow rate on the mixing ratio of water to hot water is taken into consideration.

  The influence of the hot water supply flow rate on the mixing ratio of water to hot water also affects the stability when the opening of the mixing valve is feedback controlled based on the hot water supply temperature. When the hot water supply flow rate is small, the mixing ratio of water to hot water changes greatly by slightly changing the opening of the mixing valve. Conversely, when the hot water supply flow rate is large, the mixing ratio of water to hot water does not change so much even if the opening of the mixing valve is slightly changed. When feedback control is performed based on the detected hot water temperature of the mixing valve, hunting occurs and the hot water temperature becomes unstable unless the amount of increase or decrease in the mixing valve opening is set appropriately. In other words, it takes a long time to stabilize at a desired temperature.

As a method of eliminating the influence of the hot water flow rate on the mixing ratio of water to hot water, there is a method in which an additional pipe resistance is provided in the water side route and the pressure loss characteristics are matched between the water side route and the hot water side route. Conceivable. According to this method, even if the hot water supply flow rate fluctuates, the flow rate of hot water from the hot water side passage and the flow rate of water from the water side route increase and decrease in the same way, so the mixing ratio of water to hot water is kept constant. It is. The influence of the hot water supply flow rate on the mixing ratio of water to hot water can be eliminated.
However, when this method is adopted, there is a problem that the pressure loss of the entire hot water supply system increases. If the pressure loss of the hot water supply system as a whole is large, the hot water supply flow rate is extremely reduced in an area where the water supply pressure of the water supply is low, which impairs the convenience for the user. There is a need for a technique that can adjust water and hot water mixing ratio in a mixing unit appropriately and stably and quickly supply hot water without increasing pressure loss as a whole hot water supply system.

  The present invention solves the above problems. The present invention provides a technique capable of quickly stabilizing the hot water supply temperature to a desired temperature when feedback controlling the mixing unit.

  The present invention is embodied as a hot water supply system. The hot water supply system includes a hot water storage tank, a water supply path for supplying water to the hot water storage tank, a hot water supply path for supplying hot water from the hot water storage tank, and a mixing unit for adjusting the temperature by mixing the water in the water supply path with the hot water in the hot water supply path. A mixing unit provided with a bypass path that branches from the path and bypasses the hot water tank and joins the hot water supply path, and a mixing valve that is provided in the bypass path and adjusts the mixing ratio of hot water and water by changing the opening degree Set temperature acquisition means for acquiring the hot water supply set temperature, low temperature water temperature detection means for detecting the temperature of water flowing through the bypass path as a low temperature water temperature, and hot water flowing through the hot water supply path upstream of the bypass path joining. High temperature water temperature detecting means for detecting the temperature as the high temperature water temperature, hot water temperature detecting means for detecting the temperature of hot water flowing through the hot water supply path on the downstream side where the bypass path joins as hot water supply temperature, Includes a hot water flow rate detecting means for detecting the flow rate of the water flowing through the hot-water supply path downstream of the bypass path merge as hot water flow rate, the controller adjusts the opening of the mixing valve. In the hot water supply system, the controller calculates a target mixing ratio in the mixing unit based on the hot water set temperature, the low temperature water temperature, and the high temperature water temperature, and the mixing unit based on the hot water temperature, the low temperature water temperature, and the high temperature water temperature. Is calculated, and the amount of increase or decrease in the opening of the mixing valve is determined based on the target mixing ratio, the current mixing ratio, and the hot water flow rate.

  In the hot water supply system described above, the mixing unit mixes the hot water in the hot water supply path with the hot water in the hot water supply path, thereby supplying hot water adjusted to the hot water supply set temperature. The controller uses the target mixing ratio calculated from the hot water supply set temperature and the current mixing ratio calculated from the actual hot water supply temperature to increase or decrease the opening of the mixing valve by feedback control.

The fluctuation of the mixing ratio when the opening degree of the mixing valve is increased or decreased differs depending on the magnitude of the hot water supply flow rate. When the hot water flow rate is small, the mixing ratio fluctuates greatly only by slightly increasing or decreasing the opening of the mixing valve. Conversely, when the hot water supply flow rate is large, the mixing ratio does not vary so much even if the opening of the mixing valve is slightly increased or decreased. When feedback control is performed, if the amount of increase or decrease in the opening of the mixing valve is too large, hunting occurs and the hot water supply temperature becomes unstable. On the contrary, if the increase / decrease amount of the opening degree of the mixing valve is too small, it takes a long time to stabilize the hot water supply temperature at the hot water supply set temperature.
In the above hot water supply system, not only the target mixing ratio calculated from the hot water set temperature and the current mixing ratio calculated from the actual hot water temperature, but also the hot water flow rate is taken into account, the amount of increase or decrease in the opening of the mixing valve is It is determined. By adopting such a configuration, the hot water supply temperature can be quickly stabilized at the hot water supply set temperature.

  According to the hot water supply system of the present invention, when the mixing unit is feedback-controlled, the hot water supply temperature can be quickly stabilized at a desired temperature.

Hereinafter, preferred embodiments of the present invention will be described.
(Mode 1) Hot water heated by generated heat generated by the power generation unit generating power is stored in the hot water storage tank.

  An embodiment embodying the hot water supply system of the present invention will be described with reference to the drawings. As shown in FIG. 1, the hot water supply system 100 of this embodiment is connected to a power generation unit 102, a heating terminal 160, a bath tub 170, and a hot water tap 124. The hot water supply system 100 includes a hot water storage tank 110, a heat source device 140, a mixing unit 134, a remote controller 182 and a controller 180.

  The power generation unit 102 is a power generation device using a solid polymer fuel cell. The power generation unit 102 generates power according to the power demand. When performing power generation, the power generation unit 102 drives the exhaust heat recovery pump 104. When the exhaust heat recovery pump 104 is driven, water is sucked out from the bottom of the hot water tank 110. The sucked water is heated by the generated heat in the exhaust heat recovery heat exchanger 106 and returned to the top of the hot water tank 110. The temperature of hot water returned from the power generation unit 102 to the top of the hot water tank 110 is measured by the exhaust heat recovery thermistor 108 and output to the controller 180.

  The hot water storage tank 110 stores hot water heated by the heat generated by the power generation unit 102. The hot water stored in the hot water storage tank 110 is used for hot water supply, heating, bathing, etc. A temperature stratification is formed inside the hot water tank 110, and hot water having a temperature higher than that of the lower part is stored in the upper part of the hot water tank 110. Therefore, even when the amount of heat stored in the hot water tank 110 is small, hot water can be used by discharging the hot water from the upper part of the hot water tank 110. A hot water tank thermistor 112 for detecting the hot water temperature is provided at the upper part of the hot water tank 110, and the detected temperature is output to the controller 180.

  The bottom of the hot water tank 110 is connected to a water pipe (not shown) via the hot water tank water supply path 136, the mixing unit 134 and the water supply path 132. A pressure reducing valve 126 is provided in the water supply path 132, and the water supply pressure from the water pipe is adjusted. The top of the hot water tank 110 is connected to the hot water tap 124 via the hot water tank hot water supply path 114, the mixing unit 134, and the hot water supply path 122. When the hot water tap 124 is opened, the hot water in the hot water tank 110 is pushed up from the bottom toward the top by the hot water pressure, and the hot water is discharged from the upper part of the hot water tank 110 to the hot water tank hot water supply path 114. Hot water discharged from the hot water storage tank 110 is mixed with tap water by the mixing unit 134, adjusted to a desired temperature, and then supplied to the hot water tap 124.

  The mixing unit 134 mixes tap water with hot water discharged from the upper part of the hot water tank 110 to adjust the temperature to a desired temperature. The mixing unit 134 branches part of tap water flowing from the water supply path 132 to the hot water tank water supply path 136 to the mixing bypass path 133 and mixes it with hot water flowing from the hot water tank hot water supply path 114 to the hot water supply path 122. A mixing servo valve 135 is provided at a connecting portion of the water supply path 132, the hot water tank water supply path 136, and the mixing bypass path 133. The mixing servo valve 135 has a built-in stepping motor, and when driven, the opening of the hot water tank water supply path 136 and the opening of the mixing bypass path 133 are adjusted, and the tap water flowing to the hot water tank water supply path 136 is flown. And the ratio of the flow rate of the tap water flowing to the mixing bypass path 133 is adjusted. The mixing servo valve 135 is controlled by the controller 180 and drives the stepping motor in accordance with the number of steps instructed from the controller 180. The flow rate of tap water supplied from the mixing unit 134 to the bottom of the hot water tank 110 is equal to the flow rate of hot water discharged from the upper part of the hot water tank 110 to the mixing unit 134. Therefore, by adjusting the ratio of the flow rate of tap water branched to the hot water tank water supply path 136 and the flow rate of tap water branched to the mixed bypass path 133 by the mixing servo valve 135, the hot water and the mixed bypass from the hot water tank hot water supply path 114 are adjusted. The mixing ratio of tap water from the path 133 can be adjusted.

  The hot water tank hot water supply path 114 is provided with a hot water tank hot water solenoid valve 116 and a hot water tank hot water thermistor 118. The hot water tank hot water supply electromagnetic valve 116 is controlled by a controller 180, and opens and closes when a built-in solenoid is driven. In the state where the hot water storage tank hot water supply solenoid valve 116 is closed, even if the hot water tap 124 is opened, the hot water storage tank 110 does not discharge hot water, and the hot water tap 124 receives tap water via the water supply path 132 and the mixing bypass path 133. Supplied. The hot water tank hot water supply thermistor 118 detects the temperature of hot water flowing through the hot water tank hot water supply path 114 (high temperature water temperature) and outputs it to the controller 180.

  A water supply thermistor 128 and a water supply flow rate sensor 130 are provided in the water supply path 132. The water supply thermistor 128 detects the temperature of the tap water flowing through the water supply path 132 and outputs it to the controller 180. Since the temperature of the tap water flowing through the water supply path 132 is equal to the temperature of the water flowing through the mixing bypass path, the temperature detected by the water supply thermistor 128 is equal to the temperature of the water flowing through the mixing bypass path (low temperature water temperature). The water supply flow rate sensor 130 detects the flow rate of tap water flowing through the water supply path 132 and outputs it to the controller 180. Since the flow rate of tap water flowing from the water supply path 132 to the mixing unit 134 and the flow rate of hot water flowing from the mixing unit 134 to the hot water supply path 122 are equal, the flow rate detected by the water supply flow rate sensor 130 is the hot water supplied from the mixing unit 134. Is equal to the flow rate (hot water flow rate).

  A hot water supply thermistor 120 is provided in the hot water supply path 122. Hot water supply thermistor 120 detects the temperature of hot water flowing through hot water supply path 122 (hot water supply temperature) and outputs the detected temperature to controller 180.

  The heat source unit 140 heats the hot water in the hot water storage tank 110 as necessary. When the circulation pump 138 is driven by the controller 180, hot water is sucked from the intermediate portion of the hot water storage tank 110, heated by the heat source device 140, and then returned to the top of the hot water storage tank 110. Near the outlet of the heat source unit 140, a heat source unit outlet thermistor 141 is provided. The heat source unit outlet thermistor 141 detects the temperature of the hot water heated by the heat source unit 140 and outputs it to the controller 180.

  In the hot water supply system 100 of the present embodiment, the hot water heated by the heat source device 140 is not directly sent to the mixing unit 134 or the hot water tap 124, but is temporarily returned to the top of the hot water tank 110, and hot water is supplied from the top of the hot water tank 110. It is configured to do. By adopting such a configuration, even when the hot water temperature at the outlet of the heat source device 140 changes suddenly, the upper part of the hot water storage tank 110 serves as a buffer tank, and a sudden change in the hot water supply temperature is suppressed. Hot water can be supplied to the hot water tap 124 at a stable hot water temperature.

  The path returning from the heat source unit 140 to the hot water storage tank 110 is branched into a heating heat exchange path 142 and a heating bypass path 150. A first control valve 148 is provided in the heating heat exchange path 142, and a second control valve 152 is provided in the heating bypass path 150. The first control valve 148 and the second control valve 152 are both electromagnetic valves with built-in solenoids, and are controlled by the controller 180 so that one of them is opened and the other is closed. The first control valve 148 is opened when the heating terminal 160 is heated or the bath tub 170 is reheated, and the second control valve 152 is opened when it is not.

  A heating heat exchanger 144 is provided in the heating heat exchange path 142. In the heating heat exchanger 144, heat exchange is performed between hot water heated by the heat source device 140 and returned to the hot water storage tank 110 and a heat medium (water in this embodiment) used as a heat source of the heating terminal 160. . A heating return thermistor 146 is provided on the downstream side of the heating heat exchanger 144 in the heating heat exchange path 142. The heating return thermistor 146 outputs the detected temperature to the controller 180.

  The heating terminal 160 is a heater that uses high-temperature hot water as a heat source, such as an air conditioner or a floor heater. Water used as a heating medium for the heating terminal 160 is stored in the cistern 154, and flows through the heating circulation path 158 by driving the heating pump 156, so that the heating heat exchanger 144, the heating terminal 160, and the cistern 154 It cycles in order.

  A reheating path 162 is branched from between the heating heat exchanger 144 and the heating terminal 160 in the heating circulation path 158. The reheating path 162 forms a flow path in which hot water as a heating medium heated by the heating heat exchanger 144 returns to the systern 154 via the reheating heat exchanger 164. A reheating heat valve 166 is provided in the reheating path 162. The opening and closing of the reheating heat valve 166 is controlled by the controller 180.

  A bath circulation path 168 is connected to the bath tub 170. A bath circulation pump 172 is provided in the bath circulation path 168. When the bath circulation pump 172 is driven by the controller 180, hot water is sucked out from the bathtub 170 into the bath circulation path 168. The hot water sucked out from the bathtub 170 is heated by the reheating heat exchanger 164 and returned to the bathtub 170.

  The bath circulation path 168 communicates with the hot water supply path 122 via the pouring electromagnetic valve 174, and the hot water filling of the bathtub 170 is performed by opening the pouring electromagnetic valve 174. The pouring solenoid valve 174 is controlled by the controller 180.

  The remote controller 182 includes a display board and operation switches. The user can operate the remote controller 182 to input ON / OFF of the operation of the hot water supply system 100, start / end of various operation modes, hot water supply set temperature, heating set temperature, bath set temperature, and the like. The remote controller 182 can communicate with the controller 180, and transmits the user's operation content to the controller 180.

  The controller 180 stores a control program. The controller 180 receives an operation signal from the remote controller 182, a detection signal from the feed water flow sensor 130, detection signals from various thermistors, and the like. The controller 180 processes the input signal with a control program, and controls various pumps, various valves, a burner, and the like.

  Below, the process which the controller 180 performs when the hot water supply system 100 performs a hot water supply operation is demonstrated, referring the flowchart of FIG.

  In step S202, the process waits until hot water supply is started. In this embodiment, it is determined that the hot water supply is started when the hot water supply flow rate detected by the water supply flow rate sensor 130 becomes 2.7 liters / minute or more. When hot water supply is started (YES in step S202), the process proceeds to step S204.

  In step S204, the hot water storage tank hot water supply electromagnetic valve 116 is opened. As a result, the hot water stored in the upper part of the hot water tank 110 is sent out to the hot water tank hot water supply path 114.

  In step S206, the temperature detected by the hot water tank thermistor 112 is compared with a threshold value in order to determine whether or not the heating of the hot water by the heat source device 140 is necessary. In this embodiment, if the detected temperature of the hot water tank thermistor 112 is 60 ° C. or higher (YES in step S206), it is considered that the hot water in the hot water tank 110 can be used for hot water supply without heating. . In such a case, the process proceeds to step S210, and the non-combustion hot water supply operation is performed. In the non-combustion hot water supply operation, the burner of the heat source unit 140 is not combusted, and the circulation pump 138 is not driven. In addition, when the heating operation or the reheating operation of the bath is performed in parallel with the hot water supply operation, the heat source device 140 and the circulation pump 138 are already driven. In such a case, even in the non-combustion hot water supply operation, the heat source device 140 and the circulation pump 138 are not stopped and are driven as they are.

  If the temperature detected by hot water tank thermistor 112 is less than 60 ° C. (NO in step S206), it is considered impossible to use hot water in hot water tank 110 for heating without heating. In such a case, the process proceeds to step S208, and the combustion hot water supply operation is performed. In the combustion hot water supply operation, the circulation pump 138 is driven and the burner of the heat source unit 140 is ignited. If both the first control valve 148 and the second control valve 152 are closed, the second control valve 152 is opened. As a result, hot water is sucked out from the intermediate portion of the hot water tank 110 and heated by the heat source device 140. The combustion amount of the burner of the heat source unit 140 is controlled so that the temperature detected by the heat source unit outlet thermistor 141 is 65 ° C. The hot water heated by the heat source device 140 is returned to the top of the hot water storage tank 110.

In step S210, the target mixing ratio in the mixing unit 134 is based on the hot water temperature detected by the hot water storage tank hot water thermistor 118, the low temperature water temperature detected by the hot water thermistor 128, and the hot water set temperature input to the remote controller 182. Calculate The target mixing ratio is calculated by the following formula.
Target mixing ratio = (high temperature water temperature−hot water set temperature) / (hot water set temperature−low temperature water temperature)

  In step S212, the number of steps to be instructed to the mixing servo valve 135 is calculated based on the target mixing ratio calculated in step S210 and the hot water supply flow rate detected by the hot water supply amount sensor 130.

  FIG. 3 shows the relationship between the opening of the mixing servo valve 135 and the mixing ratio in the mixing unit 134. Since the opening degree of the mixing servo valve 135 is determined by the number of steps instructed from the controller 180 to the mixing servo valve 135, the opening degree of the mixing servo valve 135 is expressed by the number of steps instructing the mixing servo valve 135 in FIG. As shown in FIG. 3, even when the number of steps instructed to the mixing servo valve 135 is the same, the mixing ratio changes according to the hot water supply flow rate. When the hot water supply flow rate is large, the opening of the mixing servo valve 135 must be increased even if the same mixing ratio is to be realized. On the contrary, when the hot water supply flow rate is small, the opening degree of the mixing servo valve 135 must be reduced even if the same mixing ratio is to be realized. This is because the water side path of the mixing unit 134 passes through the mixing bypass path 133, whereas the hot water side path of the mixing unit 134 passes through the hot water tank water supply path 136, the hot water tank 110, and the hot water tank hot water supply path 114. As a result, the pressure loss characteristics are different between the water side path and the hot water side path.

  From the stage of product shipment, the controller 180 instructs the mixing servo valve 135 for typical hot water supply flow levels of 3 liters / minute, 6 liters / minute, 9 liters / minute, and 12 liters / minute. The correspondence relationship between the number of steps to be performed and the mixing ratio realized by the mixing unit 134 is stored. The controller 180 calculates the number of steps to instruct the mixing servo valve 135 based on the hot water flow rate detected by the hot water supply amount sensor 130 and the target mixing ratio calculated in step S210.

For example, when the hot water flow rate detected by the hot water supply amount sensor 130 is 4 liters / minute, the correspondence between the number of steps and the mixing ratio when the hot water flow rate is 3 liters / minute, and the hot water flow rate is 6 liters / minute. Using the correspondence between the number of steps and the mixing ratio, the correspondence between the number of steps and the mixing ratio when the hot water flow rate is 4 liters / minute is obtained by interpolation. Then, the number of steps corresponding to the target mixture ratio is calculated using the correspondence when the hot water supply flow rate is 4 liters / minute.
In the present embodiment, when the detected hot water supply flow rate is smaller than 3 liters / minute, the correspondence in the case of 3 liters / minute is used as it is. If the detected hot water flow rate is greater than 12 liters / minute, the correspondence in the case of 12 liters / minute is used as it is.

  In step S214, the mixing servo valve 135 is instructed to the number of steps corresponding to the target mixing ratio calculated in step S212, and the mixing servo valve 135 is actually driven. Thereby, the opening degree of the mixing servo valve 135 is adjusted.

  By the processing from step S210 to step S214, the opening degree of the mixing servo valve 135 is adjusted so as to realize the target mixing ratio at which hot water supply is performed at the hot water supply set temperature. The processing from step S210 to step S214 is performed by feedforward control regardless of the hot water supply temperature detected by hot water supply thermistor 120. Compared with the case where the opening degree of the mixing servo valve 135 is adjusted by feedback control, the opening degree is adjusted so as to realize the target mixing ratio more quickly.

  In step S216, it is determined whether or not hot water supply has been completed. In the present embodiment, it is determined that the hot water supply is finished when the detected flow rate of the feed water flow rate sensor 130 becomes 2.0 liters / minute or less. If the hot water supply has not been completed (NO in step S216), the process proceeds to step S218. If it is determined that the hot water supply has been completed (YES in step S216), the process proceeds to step S226.

  At the time of performing the process of step S218, the opening degree of the mixing servo valve 135 has already been adjusted by the feedforward control from step S210 to step S214. However, the actual hot water supply temperature detected by the hot water supply thermistor 120 may not match the hot water supply set temperature due to detection errors of individual sensors and variations in the characteristics of the mixing servo valve 135. Therefore, in the processing after step S218, the opening degree of the mixing servo valve 135 is adjusted by feedback control based on the hot water supply temperature detected by the hot water supply thermistor 120.

In step S218, the target mixing ratio in the mixing unit 134 is based on the hot water temperature detected by the hot water tank hot water thermistor 118, the low temperature water temperature detected by the hot water thermistor 128, and the hot water set temperature input to the remote controller 182. Calculate The target mixing ratio is calculated by the following formula.
Target mixing ratio = (high temperature water temperature−hot water set temperature) / (hot water set temperature−low temperature water temperature)

In step S220, the current mixing in the mixing unit 134 is performed based on the high-temperature water temperature detected by the hot-water tank hot-water thermistor 118, the low-temperature water temperature detected by the hot-water thermistor 128, and the hot-water temperature detected by the hot-water thermistor 120. Calculate the ratio. The current mixing ratio is calculated by the following formula.
Current mixing ratio = (high temperature water temperature−hot water temperature) / (hot water temperature−low temperature water temperature)

  In step S222, based on the target mixing ratio calculated in step S218, the current mixing ratio calculated in step S220, and the hot water flow rate detected by the hot water supply amount sensor 130, the step number instruction value to the mixing servo valve 135 is indicated. Calculate the amount of feedback given to.

  As described in detail with respect to step S212, the controller 180 sets the typical hot water supply flow rate level at 3 liters / minute, at 6 liters / minute, at 9 liters / minute, at 12 liters / minute. In each case, the correspondence relationship between the number of steps instructed to the mixing servo valve 135 and the mixing ratio realized by the mixing unit 134 is stored.

  In step S222, first, the controller 180 calculates the number of steps corresponding to the target mixing ratio based on the hot water flow rate detected by the hot water supply amount sensor 130 and the target mixing ratio calculated in step S218. Next, the controller 180 calculates the number of steps corresponding to the current mixing ratio based on the hot water flow rate detected by the hot water supply amount sensor 130 and the current mixing ratio calculated in step S220. Then, the controller 180 calculates the difference between the number of steps corresponding to the target mixing ratio and the number of steps corresponding to the current mixing ratio, and sets the step number increase / decrease amount according to the difference.

  In step S224, based on the step number increase / decrease amount set in step S222, the mixing servo valve 135 is instructed to increase or decrease the step number, and the opening degree of the mixing servo valve 135 is adjusted. After the opening degree of the mixing servo valve 135 is adjusted, the process returns to step S216.

  Until it is determined in step S216 that the hot water supply has been completed, the processes from step S216 to step S224 are repeated. Feedback control based on the hot water supply temperature detected by the hot water supply thermistor 120 is performed, and the hot water supply temperature becomes stable at the hot water supply set temperature.

  If it is determined in step S216 that the hot water supply has been completed (YES), the process proceeds to step S226, and a process for terminating the hot water supply is performed. In step S226, it is determined whether the combustion hot water supply operation has been performed. If the combustion hot water supply operation has been performed (YES in step S226), the process proceeds to step S228. If the combustion hot water supply operation has not been performed (NO in step S226), the process proceeds to step S230.

  In step S228, the burner of the heat source unit 140 is extinguished, the circulation pump 138 is stopped, and the process proceeds to step S230. If the heating operation or the bath reheating operation is performed in parallel with the hot water supply operation, the burner of the heat source unit 140 is not extinguished, and the circulation pump 138 is not stopped, and the process proceeds to step S230.

  In step S230, the system waits for re-heating of hot water after the end of hot water supply. If re-heating is not performed even after a predetermined time has elapsed, the hot water storage tank hot water supply electromagnetic valve 116 is closed in step S232, and the process returns to step S202.

  In the hot water supply system 100 of the present embodiment, in the processing from step S210 to step S214, not only the target mixing ratio in the mixing unit 134 but also the hot water supply flow rate detected by the hot water supply amount sensor 130 is taken into the mixing servo valve 135. The number of steps to be instructed is calculated, and the opening degree of the mixing servo valve 135 is controlled by feedforward control. This makes it possible to quickly supply hot water at the hot water supply set temperature regardless of the size of the hot water supply flow rate.

  In the hot water supply system 100 of the present embodiment, in the repetitive processing from step S216 to step S224, not only the target mixing ratio and the current mixing ratio in the mixing unit 134 but also the hot water supply flow rate detected by the hot water supply water amount sensor 130 is considered. The amount of increase / decrease in the number of steps instructed to the mixing servo valve 135 is calculated, and the opening degree of the mixing servo valve 135 is controlled by feedback control. Accordingly, the hot water supply temperature can be stabilized in a short time to the hot water supply set temperature without causing hunting regardless of the hot water supply flow rate.

  In the hot water supply system 100 of the present embodiment, the controller 180 has described an example in which the relationship between the mixing ratio and the number of steps for each level of the representative hot water flow rate is stored from the stage of product shipment. It may be collected during the actual hot water supply operation. That is, the hot water temperature detected by the hot water storage tank hot water thermistor 118, the low temperature water temperature detected by the hot water thermistor 128, and the hot water thermistor 120 are detected while the hot water supply operation is actually performed at home. Based on the hot water supply temperature, the current mixing ratio of the mixing unit 134 is calculated. Then, the calculated current mixing ratio is stored in association with the amount of hot water detected by the hot water amount sensor 130 and the number of steps instructed to the mixing servo valve 135. By adopting such a configuration, it is possible to acquire a correspondence relationship between the mixing ratio in the mixing unit 134 and the number of steps commanded to the mixing servo valve 135 in a state where it is actually installed at home. More appropriate control can be performed.

Specific examples of the present invention have been described in detail above, but these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and changes of the specific examples illustrated above.
In addition, the technical elements described in the present specification or the drawings exhibit technical usefulness alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. In addition, the technology illustrated in the present specification or the drawings achieves a plurality of objects at the same time, and has technical utility by achieving one of the objects.

FIG. 1 is a system diagram of a hot water supply system 100 according to the embodiment. FIG. 2 is a flowchart for explaining hot water supply processing in the hot water supply system 100. FIG. 3 is a diagram showing a correspondence relationship between the mixing ratio in the mixing unit 134 and the number of steps instructed to the mixing servo valve 135.

Explanation of symbols

100: Hot water supply system 102: Power generation unit 104: Waste heat recovery pump 106: Waste heat recovery heat exchanger 108: Waste heat recovery thermistor 110: Hot water tank 112: Hot water tank thermistor 114: Hot water tank hot water supply path 116: Hot water tank hot water solenoid valve 118: Hot water tank hot water supply thermistor 120: Hot water supply thermistor 122: Hot water supply route 124: Hot water tap 126: Pressure reducing valve 128: Water supply thermistor 130: Water supply flow rate sensor 132: Water supply route 133: Mixing bypass route 134: Mixing unit 135: Mixing servo valve 136 : Hot water tank water supply path 138: Circulation pump 140: Heat source machine 141: Heat source machine outlet thermistor 142: Heating heat exchange path 144: Heating heat exchanger 146: Heating return thermistor 148: First control valve 150: Heating bypass path 152: No. 2 Control valve 154: Systurn 156: Heating pump 158 Heating circulation path 160: Heating terminal 162: Reheating path 164: Reheating heat exchanger 166: Reheating heat valve 168: Bath circulation path 170: Bath 172: Bath circulation pump 174: Hot water solenoid valve 180: Controller 182 :Remote controller

Claims (1)

A hot water system,
A hot water tank,
A water supply route for supplying water to the hot water tank,
A hot water supply route for supplying hot water from a hot water tank,
A mixing unit for adjusting the temperature by mixing the hot water of the hot water supply path with the water of the hot water supply path, and is provided in the bypass path, bypassing the hot water tank and joining the hot water supply path by branching from the water supply path A mixing unit comprising a mixing valve that adjusts the mixing ratio of hot water and water by changing the opening;
Set temperature acquisition means for acquiring a hot water supply set temperature;
Low temperature water temperature detecting means for detecting the temperature of water flowing through the bypass path as a low temperature water temperature;
High temperature water temperature detecting means for detecting, as a high temperature water temperature, the temperature of hot water flowing through the hot water supply path upstream from the bypass path,
Hot water supply temperature detection means for detecting the temperature of hot water flowing through the hot water supply path on the downstream side where the bypass path merges as hot water supply temperature;
Hot water flow rate detecting means for detecting the flow rate of hot water flowing through the hot water supply path on the downstream side of the bypass path as a hot water supply flow rate;
It has a controller that adjusts the opening of the mixing valve,
That controller
Based on the hot water set temperature, low temperature water temperature and high temperature water temperature, calculate the target mixing ratio in the mixing unit,
Based on the hot water temperature, low temperature water temperature and high temperature water temperature, calculate the current mixing ratio in the mixing unit,
A hot water supply system, wherein an increase / decrease amount of the opening of the mixing valve is determined based on a target mixing ratio, a current mixing ratio, and a hot water supply flow rate.

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