JP2015090256A - Hot water storage type water heater - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hot water storage type water heater capable of controlling overshoot and undershoot of a hot water supply temperature even when a temperature of water supplied to mixing means greatly changes.SOLUTION: A hot water storage type water heater includes: mixing means for discharging mixed hot water obtained by mixing a first hot water with a second hot water; first temperature detecting means detecting a temperature of the first hot water; second temperature detecting means detecting a temperature of the second hot water; third temperature detecting means detecting a temperature of the mixed hot water; and control means controlling a mixing ratio of the mixing means. The control means executes mixing ratio calculation processing for controlling the mixing ratio to a mixing ratio calculated on the basis of a detection temperature of the first temperature detecting means, a detection temperature of the second temperature detecting means, and the target temperature of the mixed hot water, when an inclination of temporal change of the detection temperature of the second temperature detecting means is larger than a preset reference, when feedback control is executed to adjust the mixing ratio on the basis of a difference between the target temperature of the mixed hot water and the detection temperature of the third temperature detecting means.

Description

  The present invention relates to a hot water storage type water heater.

  In a hot water storage water heater that adjusts the hot water supply temperature by mixing hot water supplied from a hot water storage tank and water with a hot water electric mixing valve, the temperature of the mixed hot water flowing out from the hot water electric mixing valve is detected by a sensor, and the target A technique for correcting the opening degree of the hot and cold electric mixing valve in a feedback manner based on the deviation from the temperature is widely used (see, for example, Patent Document 1).

JP 2008-164286 A

  However, in the conventional hot water storage type hot water heater, when the temperature of the water supplied to the hot water electric mixing valve fluctuates greatly for some reason, the opening degree of the mixing valve cannot be adjusted in time, and the hot water temperature greatly exceeds the target temperature. Alternatively, there is a problem that an undershoot occurs where the hot water supply temperature is significantly lower than the target temperature, and the feeling of use is impaired.

  The present invention has been made to solve the above-described problems, and can store hot water that can suppress overshoot and undershoot of the hot water supply temperature even when the temperature of the water supplied to the mixing means varies greatly. An object is to provide a hot water heater.

  A hot water storage type water heater according to the present invention includes a hot water storage tank for storing hot water, a first inlet portion, a second inlet portion, and an outlet portion. The first hot water supplied from the hot water tank to the first inlet portion, 2 mixing means for discharging the mixed warm water mixed with the second warm water having a temperature lower than the first warm water from the outlet, a mixed warm water pipe for sending the mixed warm water to the outlet terminal side, and the first warm water The first temperature detecting means for detecting the temperature, the second temperature detecting means for detecting the temperature of the second hot water, the third temperature detecting means for detecting the temperature of the mixed hot water, the first hot water and the second hot water by the mixing means And a control means for controlling the mixing ratio, and the control means performs feedback control for adjusting the mixing ratio of the mixing means based on the difference between the target temperature of the mixed hot water and the detected temperature of the third temperature detecting means. When the temperature detected by the second temperature detecting means changes over time. When the slope of the ratio is larger than a preset reference, the mixing ratio of the mixing means is calculated based on the detected temperature of the first temperature detecting means, the detected temperature of the second temperature detecting means, and the target temperature of the mixed hot water. The mixing ratio calculation process is performed to control the mixing ratio.

  According to the present invention, it is possible to suppress overshoot and undershoot of the hot water supply temperature even when the temperature of the water supplied to the mixing means varies greatly.

It is a block diagram which shows the hot water storage type water heater of Embodiment 1 of this invention. It is a figure showing the flow of the hot water during the instant hot water circulation driving | operation of the hot water storage type water heater of Embodiment 1 of this invention. It is a figure showing the flow of the hot water during the immediate hot water large flow hot water supply operation of the hot water storage type water heater of Embodiment 1 of the present invention. It is a figure showing the flow of the hot water during the instant hot water small flow hot water supply operation of the hot water storage type water heater of Embodiment 1 of the present invention. It is a graph which shows the change of the temperature of 2nd warm water when a faucet is opened largely during a quick water circulation driving | operation, and changes to a hot water high flow rate hot water supply driving | operation. It is a flowchart which shows the process which a control part performs in order to control the mixing ratio of the mixing valve of the hot water storage type water heater of Embodiment 1 of this invention.

  Embodiments of the present invention will be described below with reference to the drawings. In addition, the same code | symbol is attached | subjected to the element which is common in each figure, and the overlapping description is abbreviate | omitted.

Embodiment 1 FIG.
FIG. 1 is a configuration diagram illustrating a hot water storage type water heater according to Embodiment 1 of the present invention. As shown in FIG. 1, a hot water storage type water heater 1 according to Embodiment 1 includes a hot water storage tank 2, a mixing valve 3 as a mixing means for mixing two hot waters having different temperatures, an instant hot water pump 4, and a water supply. A pipe 5, a hot water supply pipe 8, a connection pipe 9, a mixed hot water pipe 11, a return pipe 18, and a control unit 16 are provided.

  The hot water storage tank 2 stores hot water by forming a temperature stratification in which the upper side is hot and the lower side is low. The upstream end of the water supply pipe 5 is connected to a water source such as a water supply. The downstream side of the water supply pipe 5 is branched into two hands, a water supply pipe 5a and a water supply pipe 5b. The water supply pipe 5 a is connected to the lower part of the hot water storage tank 2. The water from the water source flows into the lower part of the hot water storage tank 2 through the water supply pipe 5a, so that the hot water storage tank 2 is always kept full. The water stored in the hot water storage tank 2 is heated by a heat source (not shown) to become hot hot water. This heat source may be anything such as a heat pump heat source connected to the hot water storage tank 2 via a pipe, or an electric heater installed in the hot water storage tank 2.

  The mixing valve 3 has a first inlet portion 3a, a second inlet portion 3b, and an outlet portion 3c. The first inlet 3 a and the upper part of the hot water storage tank 2 are connected via a hot water supply pipe 8. Hot water (for example, about 80 ° C. to 90 ° C.) in the hot water storage tank 2 is supplied to the first inlet 3 a through the hot water supply pipe 8. In the following description, the hot water supplied from the hot water storage tank 2 to the first inlet 3a is referred to as “first hot water”. Hot water having a temperature lower than that of the second hot water is supplied to the second inlet 3b. In the following description, the hot water supplied to the second inlet 3b is referred to as “second hot water”. The mixing valve 3 discharges the mixed warm water, which is warm water obtained by mixing the first warm water and the second warm water, from the outlet 3c. The mixing valve 3 is configured such that the mixing ratio of the first hot water and the second hot water can be arbitrarily adjusted. For example, the mixing valve 3 controls the rotation angle of the valve body that is rotatably provided so that the ratio of the opening area on the first inlet portion 3a side and the opening area on the second inlet portion 3b side is variable. By providing the stepping motor which performs, it is comprised so that adjustment of the mixing ratio of 1st warm water and 2nd warm water is possible.

  The upstream end of the mixed hot water pipe 11 is connected to the outlet 3c. The downstream end of the mixed hot water pipe 11 is connected to the upstream end of an external hot water supply pipe 14 extending to the outside of the hot water storage type hot water heater 1. On the downstream side of the external hot water supply pipe 14, a faucet 15 that is a hot water outlet terminal that uses hot water is provided. The faucet 15 and the hot water storage type water heater 1 are further connected via an external return pipe 17 that returns hot water that has not been discharged from the faucet 15 to the hot water storage type water heater 1. The downstream end of the external return pipe 17 is connected to the upstream end of the return pipe 18 in the hot water storage type hot water heater 1. The downstream end of the return pipe 18 and the water supply pipe 5 b are connected to the second inlet 3 b of the mixing valve 3 via the connection pipe 9.

  The hot water storage type water heater 1 includes a feed water flow rate sensor 6 that detects a feed water flow rate that is a flow rate of water supplied from a water source to the feed water pipe 5, and a temperature of the first hot water supplied to the first inlet 3 a of the mixing valve 3. And a second temperature sensor 10 (second temperature detecting means) for detecting the temperature of the second hot water supplied to the second inlet 3b of the mixing valve 3. And a mixed hot water flow rate sensor 12 for detecting the flow rate of the mixed hot water flowing through the mixed hot water pipe 11 and a hot water supply temperature sensor 13 (third temperature detecting means) for detecting the temperature of the mixed hot water generated by the mixing valve 3. . The temperature of the mixed hot water generated by the mixing valve 3 is hereinafter referred to as “hot water supply temperature”.

  The water supply flow rate sensor 6 is installed in the water supply pipe 5 on the upstream side from the branch part of the water supply pipes 5a and 5b. Although the first temperature sensor 7 is installed in the upper part of the hot water storage tank 2 in the illustrated configuration, the installation location of the first temperature sensor 7 may be in the middle of the hot water supply pipe 8. The second temperature sensor 10 is installed at the connecting portion of the water supply pipe 5 b, the return pipe 18 and the connection pipe 9 in the illustrated configuration, but the installation location of the second temperature sensor 10 may be in the middle of the connection pipe 9. By installing the second temperature sensor 10 at these positions, the warm water returned from the faucet 15 through the external return pipe 17 and the return pipe 18 and the water supplied from the water source through the water supply pipe 5b. Even when the mixed water is supplied as the second warm water through the connection pipe 9 to the second inlet 3b of the mixing valve 3, the temperature of the second warm water can be detected correctly. The mixed hot water flow rate sensor 12 and the hot water supply temperature sensor 13 are installed in the middle of the mixed hot water pipe 11. In the middle of the mixed hot water pipe 11, an immediate hot water pump 4 is further installed. The place where the instant hot water pump 4 is installed is not limited to the middle of the mixed hot water pipe 11 and may be anywhere on the circulation circuit described later.

  The control unit 16 (control unit) is configured by, for example, a microcomputer, and includes a storage unit including a ROM, a RAM, a nonvolatile memory, and the like, and an arithmetic process that executes a predetermined arithmetic process based on a program stored in the storage unit A device (CPU) and an input / output port for inputting / outputting external signals to / from the arithmetic processing unit are provided. The control unit 16 includes the mixing valve 3, the hot water pump 4, the feed water flow sensor 6, the first temperature sensor 7, the second temperature sensor 10, the mixed hot water flow sensor 12, the hot water temperature sensor 13, and the user interface device. Each is connected to a remote control device 20. The user can set the temperature of hot water used in the faucet 15 with the remote control device 20.

  The control unit 16 has a function of performing feedback control for adjusting the mixing ratio of the mixing valve 3 based on the deviation between the target temperature and the detected temperature of the hot water supply temperature sensor 13 using the temperature set by the remote controller 20 as a target temperature. . The control unit 16 has a function of calculating the mixing ratio of the mixing valve 3 based on the detected temperature of the first temperature sensor 7, the detected temperature of the second temperature sensor 10, and the target temperature.

  In the hot water storage type water heater 1 of the first embodiment, by operating the immediate hot water pump 4, the mixing valve 3, the mixed hot water pipe 11, the external hot water pipe 14, the external return pipe 17, the return pipe 18 and the connection pipe 9 are connected. An instant hot water circulation operation in which hot water is circulated in the circulation circuit that is formed can be performed. Even when the faucet 15 is closed, the hot water circulation operation is performed to circulate the mixed hot water adjusted to the target temperature by the mixing valve 3 in the vicinity of the mixed hot water pipe 11, the external hot water supply pipe 14, and the faucet 15. Can be supplied. For this reason, when the user opens the faucet 15, the mixed hot water adjusted to the target temperature can be immediately discharged from the faucet 15.

  FIG. 2 is a diagram illustrating a flow of hot water during the hot water circulation operation of the hot water storage type hot water heater 1 according to the first embodiment. FIG. 2 shows a state in which the quick water pump 4 is operated but the faucet 15 is closed. Below, the target temperature of mixed warm water is demonstrated as 60 degreeC. The controller 16 performs the feedback control that operates the immediate hot water pump 4 and adjusts the mixing ratio of the mixing valve 3 based on the deviation between the target temperature and the temperature detected by the hot water temperature sensor 13. The mixed hot water is discharged. The mixed hot water circulates through the mixed hot water pipe 11, the external hot water supply pipe 14, the external return pipe 17, the return pipe 18 and the connection pipe 9. The warm water returning from the external return pipe 17 to the return pipe 18 of the hot water storage type hot water heater 1 is hereinafter referred to as “return hot water”. Although the temperature of the return hot water varies depending on the length of the external hot water supply pipe 14 and the external return pipe 17, the temperature of the mixed hot water generated by the mixing valve 3, that is, the hot water supply temperature is reduced by, for example, about 5 ° C. due to heat dissipation. . For this reason, below, the temperature of return warm water is explained as 55 ° C. During the hot water circulation operation with the faucet 15 closed, the return hot water that has passed through the return pipe 18 branches into the connection pipe 9 and the water supply pipe 5b. That is, 55 ° C. return hot water is supplied to the second inlet 3b of the mixing valve 3 as the second hot water. For this reason, the temperature of 2nd warm water is stabilized at 55 degreeC same as the temperature of return warm water. First hot water of, for example, 80 ° C. to 90 ° C. is supplied from the hot water storage tank 2 through the hot water supply pipe 8 to the first inlet 3 a of the mixing valve 3. A part of the return hot water flows into the hot water storage tank 2 through the water supply pipes 5b and 5a. If the faucet 15 is opened in such a state of the hot water circulation operation, warm hot water can be immediately discharged from the faucet 15.

  FIG. 3 is a diagram showing the flow of hot water during the hot water high flow rate hot water supply operation of the hot water storage type water heater 1 of the first embodiment. 3 is a state in which the hot water pump 4 is operated, the faucet 15 is opened relatively large, and hot water is discharged from the faucet 15 at a relatively large flow rate (for example, 8 L / min). It is. In the hot water large flow rate hot water supply operation, since the flow rate discharged from the faucet 15 is large, the flow rate returning to the external return pipe 17 is relatively small. Water having a flow rate equal to the flow rate discharged from the faucet 15 is supplied to the water supply pipe 5 from the water source. The water flowing through the water supply pipe 5 is divided into water supply pipes 5 a and 5 b and supplied to both the hot water storage tank 2 and the connection pipe 9. Therefore, the mixed water of 55 ° C. return hot water supplied from the return pipe 18 and low-temperature water supplied from the water source through the water supply pipe 5 b passes through the connection pipe 9 to the second inlet 3 b of the mixing valve 3. Supplied. For this reason, the temperature of the 2nd warm water supplied to the 2nd entrance part 3b turns into a temperature lower than 55 degreeC return warm water. In the following description, it is assumed that the temperature of the second warm water during the hot water large flow hot water supply operation is 30 ° C. When the rapid hot water supply operation is continued, the temperature of the second hot water is stabilized at 30 ° C. For this reason, the controller 16 performs feedback control for adjusting the mixing ratio of the mixing valve 3 based on the deviation between the target temperature and the temperature detected by the hot water temperature sensor 13, so that the hot water temperature is stable at the target temperature of 60 ° C. To do.

  FIG. 4 is a diagram illustrating the flow of hot water during the hot water low flow hot water supply operation of the hot water storage type water heater 1 according to the first embodiment. 4 is a state in which the hot water pump 4 is operated, the faucet 15 is opened relatively small, and hot water is discharged from the faucet 15 at a relatively small flow rate (for example, 3 L / min). It is. In the hot water small flow rate hot water supply operation, since the flow rate of the hot water discharged from the faucet 15 is small, the flow rate returning to the external return pipe 17 and the return pipe 18 is relatively large. Water having a flow rate equal to the flow rate discharged from the faucet 15 is supplied to the water supply pipe 5 from the water source. The return hot water that has passed through the return pipe 18 is divided into a connection pipe 9 and a water supply pipe 5b. The water flowing through the water supply pipe 5 does not flow into the water supply pipe 5b but flows into only the water supply pipe 5a. In the water supply pipe 5 a, the low temperature water from the water source and the return hot water flowing from the return pipe 18 through the water supply pipe 5 b merge and flow into the hot water storage tank 2. Only the return hot water at 55 ° C. is supplied to the second inlet 3 b of the mixing valve 3 as the second hot water. For this reason, if the hot water small flow hot water supply operation is continued, the temperature of the second hot water is stabilized at 55 ° C., which is the same as the temperature of the return hot water. For this reason, the controller 16 performs feedback control for adjusting the mixing ratio of the mixing valve 3 based on the deviation between the target temperature and the temperature detected by the hot water temperature sensor 13, so that the hot water temperature is stable at the target temperature of 60 ° C. To do.

  As described above, the temperature (30 ° C.) of the second hot water during the immediate hot water flow operation is higher than the temperature (55 ° C.) of the second hot water during the hot water circulation operation or the quick hot water flow operation. Greatly reduced. For this reason, the mixing ratio of the second warm water in the mixing valve 3 at the time of the immediate hot water flow rate hot water supply operation, that is, the opening degree on the second inlet 3b side is compared with that at the time of the immediate hot water circulation operation or the immediate hot water small flow rate hot water supply operation. , Significantly smaller. Further, the mixing ratio of the first warm water in the mixing valve 3 at the time of the immediate hot water large flow hot water supply operation, that is, the opening degree on the first inlet 3a side is compared with that in the quick hot water circulation operation or the quick hot water small flow hot water supply operation. Greatly big. Thus, the mixing ratio of the mixing valve 3 is greatly different between the immediate hot water large flow hot water supply operation and the immediate hot water circulation operation or the immediate hot water low flow hot water supply operation. When the hot water supply temperature is feedback-controlled in the immediate hot water circulation operation or the immediate hot water low flow hot water supply operation, when the faucet 15 is opened widely and the transition is made to the immediate hot water large flow hot water supply operation, the temperature of the second hot water rapidly increases. descend. In that case, since the adjustment of the mixing ratio of the mixing valve 3 by feedback control is not in time, an undershoot occurs in which the hot water supply temperature temporarily falls below the target temperature temporarily. On the contrary, when the hot water supply temperature is feedback-controlled in the immediate hot water flow rate hot water supply operation, when the opening degree of the faucet 15 is decreased and the transition is made to the immediate hot water small flow rate hot water supply operation or the immediate hot water circulation operation, the second hot water The temperature rises rapidly. In that case, since the adjustment of the mixing ratio of the mixing valve 3 by feedback control is not in time, an overshoot occurs in which the hot water supply temperature temporarily exceeds the target temperature temporarily.

  In the first embodiment, in order to suppress the above-described undershoot and overshoot, when the temperature of the second hot water flowing into the second inlet portion 3b of the mixing valve 3 changes suddenly, the control unit 16 The mixing ratio of the mixing valve 3 is calculated based on the detected temperature of the first temperature sensor 7, the detected temperature of the second temperature sensor 10, and the target temperature, and the actual mixing ratio of the mixing valve 3 becomes the calculated mixing ratio. Thus, the mixing ratio calculation process is controlled.

  FIG. 5 is a graph showing a change in the temperature of the second hot water when the faucet 15 is greatly opened during the immediate hot water circulation operation and the state is changed to the immediate hot water flow rate hot water supply operation. FIG. 6 is a flowchart illustrating a process executed by the control unit 16 in order to control the mixing ratio of the mixing valve 3 in the hot water storage type water heater 1 according to the first embodiment.

  When the process is started in step S1 of FIG. 6, the control unit 16 performs feedback control of the mixing valve 3 (step S2). That is, in step S2, the control unit 16 adjusts the mixing ratio of the mixing valve 3 based on the deviation between the target temperature and the temperature detected by the hot water temperature sensor 13, so that the hot water temperature detected by the hot water temperature sensor 13 is the target. It controls so that it may correspond to 60 degreeC which is temperature.

  When performing the feedback control in step S2, the control unit 16 compares the slope of the temporal change in the temperature detected by the second temperature sensor 10 with a preset reference, thereby providing the second inlet of the mixing valve 3. It is determined whether or not the temperature of the second hot water flowing into the section 3b has changed abruptly (step S3). In the first embodiment, the control unit 16 monitors the detected temperature of the second temperature sensor 10 at a predetermined time interval (in the first embodiment, every 0.5 seconds), and the predetermined temperature range (the main temperature). In the first embodiment, the temperature is 2 ° C.) When the fluctuation is less than 2 ° C., it is determined that there is no sudden change in the temperature of the second hot water. Judge that it changed suddenly. That is, in step S3, when the slope of the temporal change in the temperature detected by the second temperature sensor 10 is less than 2 ° C. per 0.5 second, the controller 16 determines that the temperature of the second hot water is suddenly changed. Judge that there is no. In this case, the control unit 16 returns to step S2 and continues the feedback control.

  On the other hand, in step S3, when the slope of the temporal change in the temperature detected by the second temperature sensor 10 is 2 ° C. or more per 0.5 second, the control unit 16 suddenly changes the temperature of the second hot water. Is determined. In this case, the control unit 16 proceeds to step S4.

  The process of step S3 will be described based on the example shown in FIG. As described above, during the hot water circulation operation, the temperature of the second hot water is stabilized at 55 ° C., which is substantially equal to the temperature of the return hot water in the return pipe 18. For this reason, during the hot water circulation operation, it is determined NO in Step S3, so that the feedback control in Step S2 is continued and the mixing ratio of the mixing valve 3 converges to a stable state. In such a state where the hot water circulation operation is in progress, when the faucet 15 is greatly opened and the transition is made to the quick water large flow hot water supply operation, as shown in FIG. 5, the water source passes through the water supply pipe 5b. The supplied low-temperature water begins to flow into the connecting pipe 9 and returns to the connecting pipe 9 and mixes with the returning hot water, whereby the temperature of the second hot water rapidly decreases. At this time, since the change in the temperature detected by the second temperature sensor 10 per 0.5 second is 1 ° C. less than 2 ° C. in the section B in FIG. 5, NO is determined in step S3, and the process proceeds to step S2. To do. On the other hand, in the section C in FIG. 5, the change in the temperature detected by the second temperature sensor 10 per 0.5 second is 2 ° C. or more. Therefore, YES is determined in step S3, and the process proceeds to step S4.

In step S4, the control unit 16 calculates the mixing ratio of the mixing valve 3 based on the detected temperature of the first temperature sensor 7, the detected temperature of the second temperature sensor 10, and the target temperature, and sets the calculated mixing ratio to the calculated mixing ratio. A mixing ratio calculation process for controlling the mixing valve 3 is performed. In the first embodiment, the control unit 16 sets the detected temperature of the first temperature sensor 7 to T1, the detected temperature of the second temperature sensor 10 to T2, the target temperature to Ts, and the mixing ratio of the first hot water in the mixing valve 3. When M1, M1 is calculated based on the following equation.
M1 = (Ts−T2) / (T1−T2)

  Thus, in step S4, the feedback control based on the detected temperature of the hot water supply temperature sensor 13 is temporarily suspended, and the mixing valve 3 is based on the detected temperature of the first temperature sensor 7 of the mixing valve 3 and the detected temperature of the second temperature sensor 10. The hot water supply temperature is controlled in a feed-forward manner by determining the mixing ratio of 3. For this reason, even when the temperature of the second hot water changes abruptly, undershoot or overshoot of the hot water supply temperature can be reliably suppressed, and the mixed hot water can be maintained at a temperature close to the target temperature. . That is, in the case of the example shown in FIG. 5, when it is assumed that the feedback control is continued without performing the mixing ratio calculation process in step S4, hot water supply is performed against the rapid decrease in the temperature of the second hot water. Adjustment of the mixing ratio of the mixing valve 3 based on the temperature detected by the temperature sensor 13 cannot follow, and an undershoot of the hot water supply temperature occurs. On the other hand, according to the first embodiment, an abrupt decrease in the temperature of the second hot water is detected in step S3, and an undershoot of the hot water supply temperature is generated by performing the mixing ratio calculation process in step S4. Can be reliably suppressed.

  After performing the mixture ratio calculation process, the controller 16 determines the temperature of the second hot water when the gradient of the temporal change in the detected temperature of the second temperature sensor 10 becomes smaller than a preset reference. Is determined to have ended, and the feedback control of the mixing valve 3 is resumed. In other words, in the first embodiment, the control unit 16 determines that the mixing valve 3 of the mixing valve 3 is in a state where the gradient of the temporal change in the temperature detected by the second temperature sensor 10 is less than 2 ° C. per 0.5 second. Resume feedback control. In the case of the example shown in FIG. 5, since the change in the detected temperature of the second temperature sensor 10 per 0.5 second is 0.5 ° C., which is less than 2 ° C., in the section D in FIG. 16 resumes the feedback control of the mixing valve 3.

  Thus, in this Embodiment 1, by performing a mixture ratio calculation process, generation | occurrence | production of the undershoot and overshoot of the hot water supply temperature to the faucet 15 can be suppressed reliably.

  As described above, the hot water storage type water heater 1 enters the state of the hot water large flow hot water supply operation shown in FIG. 3 when the tap water flow rate of the faucet 15 is large, and when the tap water flow rate of the faucet 15 is small, 4 is brought into a state of an immediate hot water small flow hot water supply operation shown in FIG. The outlet flow rate of the faucet 15 is a boundary flow rate between the range of the large flow rate at which the immediate hot water flow rate hot water supply operation state is reached and the range of the low flow rate at which the hot water low flow rate hot water supply operation state is established (for example, 4 L / min. In the case of “boundary flow rate”), when the mixing ratio of the mixing valve 3 is significantly changed by the mixture ratio calculation process, the operation is changed from the immediate hot water large flow hot water supply operation to the immediate hot water small flow hot water supply operation or vice versa. The state may change. As can be seen from FIGS. 3 and 4, when the flow direction of the water supply pipe 5b is reversed, the hot water large flow hot water supply operation and the quick hot water small flow hot water operation are switched. Hereinafter, an example will be described.

  Here, it is assumed that the faucet 15 is opened during the immediate hot water circulation operation, the flow rate of the faucet 15 is 4 L / min, which is the boundary flow rate, and a transition is made to the immediate hot water flow rate hot water supply operation. Accompanying the transition from the immediate hot water circulation operation to the immediate hot water flow rate hot water supply operation, the low temperature water supplied from the water source through the water supply pipe 5b starts to flow into the connection pipe 9, and returns from the return pipe 18 to the connection pipe 9. By mixing with warm water, the temperature of the 2nd warm water falls rapidly from 55 degreeC to 30 degreeC, for example. Accordingly, the control unit 16 performs a mixture ratio calculation process. By this mixing ratio calculation process, the mixing valve 3 is greatly changed so that the mixing ratio of the first hot water, which is hot water from the hot water storage tank 2, is increased and the mixing ratio of the second hot water is decreased. . That is, in this mixing ratio calculation process, the opening degree of the mixing valve 3 is significantly changed so that the opening degree on the first inlet portion 3a side is enlarged and the opening degree on the second inlet portion 3b side is reduced. . As a result, the flow rate of the second warm water flowing from the connection pipe 9 to the second inlet 3b is rapidly reduced, so that it is difficult for water to flow in the direction from the water source to the connection pipe 9 through the water supply pipe 5b. On the other hand, the flow rate of the first hot water flowing into the first inlet portion 3a of the mixing valve 3, that is, the flow rate of hot water flowing out from the hot water storage tank 2 to the hot water supply pipe 8 increases rapidly, and therefore flows into the hot water storage tank 2 from the water supply pipe 5a. The flow rate of water increases. For this reason, it becomes easy for water to flow from the return pipe 18 to the water supply pipe 5a through the water supply pipe 5b. For these reasons, the flow direction of the water supply pipe 5b is reversed, and a flow is formed in the direction from the return pipe 18 to the water supply pipe 5a through the water supply pipe 5b. As a result, an immediate hot water small flow hot water supply operation is set. In this way, due to the mixing ratio calculation process accompanying the transition from the immediate hot water circulation operation to the immediate hot water flow rate hot water supply operation, the immediate hot water large flow rate hot water supply operation further shifts to the immediate hot water small flow rate hot water supply operation.

  When the transition from the immediate hot water flow rate hot water supply operation to the immediate hot water flow rate hot water operation is performed as described above, the inflow of the low temperature water to the connection pipe 9 is stopped, and only the return hot water from the return pipe 18 flows into the connection pipe 9. Since it will be in a state, the temperature of 2nd warm water will rise rapidly from 30 degreeC to 55 degreeC, for example. Accordingly, the control unit 16 performs a mixture ratio calculation process. By this mixing ratio calculation process, the mixing ratio of the mixing valve 3 is greatly changed so as to decrease the mixing ratio of the first hot water from the hot water storage tank 2 and increase the mixing ratio of the second hot water. That is, in this mixing ratio calculation process, the opening of the mixing valve 3 is significantly changed so as to reduce the opening on the first inlet 3a side and increase the opening on the second inlet 3b side. . As a result, the flow rate of the first hot water flowing into the first inlet portion 3a of the mixing valve 3, that is, the flow rate of hot water flowing out from the hot water storage tank 2 to the hot water supply pipe 8 is rapidly reduced, and therefore flows into the hot water storage tank 2 from the water supply pipe 5a. Water flow decreases rapidly. For this reason, it becomes difficult for water to flow from the return pipe 18 through the water supply pipe 5b to the water supply pipe 5a. On the other hand, since the flow rate of the second warm water flowing from the connection pipe 9 to the second inlet 3b increases rapidly, water easily flows in the direction from the water source to the connection pipe 9 through the water supply pipe 5b. For these reasons, the flow direction of the water supply pipe 5b is reversed again, and a flow is formed in the direction from the water source to the connection pipe 9 through the water supply pipe 5b. As a result, the hot water large flow hot water supply operation is entered. In this way, due to the mixing ratio calculation processing accompanying the transition from the immediate hot water flow rate hot water supply operation to the immediate hot water flow rate hot water operation, the immediate hot water low flow rate hot water operation returns to the immediate hot water flow rate hot water operation. .

  When the outlet flow rate of the faucet 15 is the boundary flow rate, as described above, each time the mixing ratio calculation process is performed, the immediate hot water large flow hot water supply operation and the instant hot water small flow hot water supply operation are switched, so that There is a possibility that a phenomenon occurs in which the hot water flow rate hot water supply operation and the immediate hot water small flow rate hot water supply operation are alternately repeated. When this phenomenon occurs, the hot water supply temperature to the faucet 15 is not stable forever, and hunting may occur.

  In order to reliably suppress the occurrence of the hunting described above, the control unit 16 counts the number of times that the mixture ratio calculation process has been executed, and when the number of times of execution reaches a preset number (for example, three times), Thereafter, the execution of the mixture ratio calculation process may be prohibited. Thereby, even when the tap water flow rate of the faucet 15 is the boundary flow rate, it is possible to reliably suppress the rapid hot water flow hot water supply operation and the quick hot water small flow hot water supply operation from being repeated alternately. It can be reliably suppressed. After prohibiting the execution of the mixing ratio calculation process in this way, when the hot-water state from the faucet 15 changes due to a change in the opening of the faucet 15 or the presence or absence of the immediate hot water pump 4 (ON / OFF) Since the possibility of occurrence of hunting can be considered to have disappeared, the count of the number of executions of the mixture ratio calculation process may be cleared to zero, that is, the prohibition of the mixture ratio calculation process may be cancelled. In that case, regarding the change in the hot water state from the faucet 15, the hot water from the faucet 15 when the feed water flow rate detected by the feed water flow rate sensor 6 changes over a preset threshold value (for example, 1 L / min). It can be considered that the state has changed. Alternatively, when the mixed hot water flow rate detected by the mixed hot water flow rate sensor 12 changes across a preset threshold value (for example, 1 L / min), it may be considered that the state of the hot water from the faucet 15 has changed. The threshold value may be 0 L / min. That is, when the feed water flow rate detected by the feed water flow rate sensor 6 becomes zero, it may be considered that the state of the hot water from the faucet 15 has changed, or the mixed hot water flow rate detected by the mixed hot water flow rate sensor 12 is zero. It may be considered that the state of the hot water from the faucet 15 has changed. In summary, after the control unit 16 prohibits the execution of the mixing ratio calculation process, when the mixed hot water flow rate detected by the mixed hot water flow rate sensor 12 changes to a preset threshold value, the feed water flow rate sensor 6 detects it. When the supplied water flow rate is changed to a preset threshold value, the presence or absence (ON / OFF) of the operation of the immediate hot water pump 4 is changed, and in at least one of the cases, there is no possibility of occurrence of hunting. Therefore, the prohibition of the mixture ratio calculation process may be lifted.

  Moreover, it can replace with said method and can suppress generation | occurrence | production of the hunting mentioned above reliably also by the following methods. In the case of this method, the control unit 16 stores the sign of the slope of the temporal change in the detected temperature of the second temperature sensor 10 when the mixture ratio calculation process is executed. In the case of transition from the immediate hot water small flow hot water supply operation to the immediate hot water high flow hot water supply operation, the gradient of the temporal change in the temperature detected by the second temperature sensor 10 becomes negative as shown in FIG. On the other hand, when a transition is made from an immediate hot water flow rate hot water supply operation to an immediate hot water flow rate hot water operation, the slope of the temporal change in the temperature detected by the second temperature sensor 10 is positive. Therefore, the control unit 16 determines that the slope of the temporal change in the detected temperature of the second temperature sensor 10 is the slope of the temporal change in the detected temperature of the second temperature sensor 10 when the mixture ratio calculation process was executed last time. On the other hand, if the reverse is true, the execution of the mixture ratio calculation process is prohibited. Thereby, since it can suppress reliably that an instant hot water flow rate hot water supply driving | operation and an instant hot water flow rate hot water supply operation repeat alternately, generation | occurrence | production of hunting can be suppressed reliably. Also in this method, similarly to the above method, after the control unit 16 prohibits the execution of the mixing ratio calculation process, the mixed hot water flow rate detected by the mixed hot water flow rate sensor 12 changes to a preset threshold value. When the feed water flow rate detected by the feed water flow rate sensor 6 changes to a preset threshold value, the presence / absence (ON / OFF) of the immediate hot water pump 4 changes, or at least one of the cases. Since it can be considered that the possibility of occurrence of hunting has been eliminated, the prohibition of the mixture ratio calculation processing may be lifted.

DESCRIPTION OF SYMBOLS 1 Hot water storage type hot water supply machine, 2 Hot water storage tank, 3 Mixing valve, 3a 1st inlet part, 3b 2nd inlet part, 3c outlet part, 4 Instant hot water pump, 5, 5a, 5b Water supply pipe, 6 Water supply flow rate sensor, 7th 1 temperature sensor, 8 hot water supply pipe, 9 connecting pipe, 10 second temperature sensor, 11 mixed hot water pipe, 12 mixed hot water flow sensor, 13 hot water temperature sensor, 14 external hot water pipe, 15 water tap, 16 control unit, 17 external return Pipe, 18 return pipe, 20 remote control device

Claims (5)

A hot water storage tank for storing hot water,
The first hot water supplied from the hot water storage tank to the first inlet portion and supplied to the second inlet portion, and having a temperature higher than that of the first hot water. Mixing means for discharging the mixed warm water mixed with the low second warm water from the outlet portion;
A mixed hot water pipe for sending the mixed hot water to the hot water terminal side;
First temperature detecting means for detecting the temperature of the first hot water;
Second temperature detecting means for detecting the temperature of the second hot water;
Third temperature detecting means for detecting the temperature of the mixed hot water;
Control means for controlling the mixing ratio of the first hot water and the second hot water by the mixing means;
With
The control means performs the second temperature detection when performing feedback control for adjusting the mixing ratio of the mixing means based on the difference between the target temperature of the mixed hot water and the detected temperature of the third temperature detecting means. When the slope of the change in the detected temperature of the means over time is larger than a preset reference, the mixing ratio of the mixing means is set to the detected temperature of the first temperature detecting means and the second temperature detecting means. A hot water storage type hot water heater that performs a mixing ratio calculation process for controlling a mixing ratio calculated based on a detected temperature and a target temperature of the mixed hot water. A return pipe through which hot water returns from the hot spring terminal side;
A water supply pipe through which water supplied from a water source passes,
A connection pipe connecting the return pipe and the water supply pipe to the second inlet of the mixing means;
A pump for circulating hot water in a circulation circuit formed including the mixing means, the mixed hot water pipe, the return pipe and the connection pipe;
The hot water storage type water heater according to claim 1.   The hot water storage hot water supply apparatus according to claim 1 or 2, wherein the control means prohibits the mixture ratio calculation process when the number of times the mixture ratio calculation process is executed reaches a preset number.   The control means is configured such that the slope of the temporal change in the detected temperature of the second temperature detecting means is the slope of the temporal change in the detected temperature of the second temperature detecting means when the mixture ratio calculation process was executed last time. The hot water storage type water heater according to claim 1 or 2, wherein the mixing ratio calculation process is prohibited when the direction is opposite to the above.   The control means, after prohibiting the mixing ratio calculation process, when the flow rate of the mixed hot water changes to a preset threshold value, when the flow rate of water supplied from the water source changes to a preset threshold value The hot water storage according to claim 3 or 4, wherein the prohibition of the mixing ratio calculation process is canceled in at least one of cases where the presence or absence of operation of a pump for sending the mixed hot water to the hot water terminal side changes. Type water heater.

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