Water heater

Abstract

To provide a water heater capable of further stabilizing a hot water supply temperature in a general hot water supply passage even when simultaneous hot water supply in a bath hot water supply passage is started during hot water supply in the general hot water supply passage.SOLUTION: A water heater includes a hot water storage unit and a heat source unit. The hot water storage unit includes: a hot water storage tank that stores hot water supplied from the heat source unit; a first mixing valve for mixing the hot water supplied from the hot water storage tank with water supplied from outside and causing the mixture to flow into a general hot water supply passage side; a second mixing valve for mixing the hot water supplied from the hot water storage tank with water supplied from outside and causing the mixture to flow into a bath hot water supply passage side; and a control section that controls valve openings of the first mixing valve and the second mixing valve. When hot water is simultaneously supplied to the general hot water supply passage side and the bath hot water supply passage side, the control section alternately starts first control for increasing the valve opening of the first mixing valve and second control for increasing the valve opening of the second mixing valve.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a water heater capable of supplying hot water simultaneously to a general hot water supply line and a bath hot water supply line.

Background Art

[0002] As a water heater capable of supplying hot water simultaneously to both a general hot water supply line connected to a kitchen faucet or a shower in a bath and a bath hot water supply line connected to a bathtub, an automatic water heater of Patent Document 1 is known. For example, in the abstract of the same document, there is a description of the problem as "obtaining an automatic water heater capable of stably controlling the hot water supply temperature from a mixing valve with high priority (for example, a shower) even when the driving conditions of the mixing valve with high priority (for example, a shower) change."

[0003] Also, in paragraph 0050 of the same document, it is described that "FIG. 9 is a diagram showing the relationship between the opening degrees of the general hot water supply side mixing valve 2a and the bath hot water supply side mixing valve 2b and the general hot water supply temperature and the bath hot water supply temperature when the simultaneous hot water supply correction coefficient Km is not applied to the opening degree control of the bath hot water supply side mixing valve 2b (the one with lower priority), (a) is a diagram showing the relationship between the opening degrees of the general hot water supply side mixing valve 2a and the bath hot water supply side mixing valve 2b and the elapsed time, and (b) is a diagram showing the relationship between the general hot water supply temperature and the bath hot water supply temperature and the elapsed time. Also, FIG. 10 is a diagram showing the relationship between the opening degrees of the general hot water supply side mixing valve 2a and the bath hot water supply side mixing valve 2b and the general hot water supply temperature and the bath hot water supply temperature when the simultaneous hot water supply correction coefficient Km is applied to the opening degree control of the bath hot water supply side mixing valve 2b (the one with lower priority), (a) is a diagram showing the relationship between the opening degrees of the general hot water supply side mixing valve 2a and the bath hot water supply side mixing valve 2b and the elapsed time, and (b) is a diagram showing the relationship between the general hot water supply temperature and the bath hot water supply temperature and the elapsed time."

[0004] Furthermore, Paragraph 0051 of the same document states that "When the simultaneous hot water supply correction coefficient Km is not applied, the opening degrees of the general hot water supply side mixing valve 2a and the bath hot water supply side mixing valve 2b are controlled independently, so the opening degree of the bath hot water supply side mixing valve 2b is too large, and the undershoot amount of the general hot water supply temperature has increased. However, when the simultaneous hot water supply correction coefficient Km is applied, as the en (the deviation amount between the set temperature and the actual hot water supply temperature) of the general hot water supply increases, the change amount of the opening degree of the bath hot water supply side mixing valve 2b becomes smaller, and the undershoot amount of the general hot water supply temperature has decreased."

[0005] Thus, in the automatic hot water supply device of Patent Document 1, when the driving conditions of the mixing valve change (such as when the set temperature of the bath hot water supply is increased), the undershoot of the general hot water supply temperature is suppressed by applying the simultaneous hot water supply correction coefficient Km to the opening degree control of the mixing valve (see FIGS. 9 and 10 of the same document).

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0007] However, although the undershoot of the general hot water supply temperature in FIG. 10 of Patent Document 1 is suppressed compared to FIG. 9 of the same document, it continues for a corresponding period, and the general hot water supply at a temperature lower than the set temperature continues for a corresponding period. Therefore, it cannot be said that the problem of Patent Document 1, sufficient stability of the hot water supply temperature, has been achieved.

[0008] Therefore, an object of the present invention is to provide a hot water supply machine that can make the hot water supply temperature of the general hot water supply path more stable even when the simultaneous hot water supply of the bath hot water supply path is started during the hot water supply of the general hot water supply path.

Means for Solving the Problems

[0009] In order to solve the above problems, the water heater of the present invention is a water heater having a hot water storage unit and a heat source unit, wherein the hot water storage unit includes a hot water storage tank for storing hot water supplied from the heat source unit, a first mixing valve for mixing the hot water supplied from the hot water storage tank and the water supplied from the outside and flowing out to the general hot water supply path side, a second mixing valve for mixing the hot water supplied from the hot water storage tank and the water supplied from the outside and flowing out to the bath hot water supply path side, and a control unit for controlling the valve opening degrees of the first mixing valve and the second mixing valve. When simultaneously supplying hot water to the general hot water supply path side and the bath hot water supply path side, the control unit is configured as a water heater that alternately starts a first control for increasing the valve opening degree of the first mixing valve and a second control for increasing the valve opening degree of the second mixing valve.

Advantages of the Invention

[0010] According to the water heater of the present invention, even when starting simultaneous hot water supply to the bath hot water supply path during hot water supply to the general hot water supply path, the hot water supply temperature of the general hot water supply path can be made more stable.

Brief Description of the Drawings

[0011]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Modes for Carrying Out the Invention

[0012] Hereinafter, embodiments of the water heater 100 according to the present invention will be described with reference to the drawings.

Embodiment

[0013] Figure 1 is a schematic configuration diagram of a water heater 100 according to an embodiment. As shown here, the water heater 100 is a device that connects a hot water storage unit 1 and a heat source unit 2 with pipes and communicably connects the hot water storage unit 1 and an operation unit 3. A mixing faucet 4 is also provided outside the water heater 100. Each will be sequentially described below.

[0014] <Heat source unit 2> The heat source unit 2 is a device that boils water at room temperature (for example, 20°C) to generate hot water at a high temperature (for example, 60°C). Since a well-known heat source such as a heat pump can be used for the heat source unit 2 of this embodiment, the details of the heat source unit 2 will be omitted below.

[0015] <Operation unit 3> The operation unit 3 is a user interface that the user operates when individually setting the temperatures of general hot water supply and bath hot water supply or starting the automatic water filling of the bath. Hereinafter, the set temperature of general hot water supply set by the user will be referred to as Ta, and the set temperature of bath hot water supply will be referred to as Tb.

[0016] <Hot water storage unit 1> The hot water storage unit 1 is a device that supplies hot water according to the set temperature to the general hot water supply line and the bath hot water supply line, and also has a function of supplying room temperature water to the heat source unit 2 and a function of storing the high-temperature hot water supplied from the heat source unit 2. As shown in the figure, this hot water storage unit 1 has a hot water storage tank 11, a pressure reducing valve 12, mixing valves 13a, 13b, an electromagnetic valve 14, temperature sensors 15a to 15d, and a control unit 16, and each component is pipe-connected as shown in the figure.

[0017] Although not shown in the figure, each of the mixing valves 13a, 13b, and the electromagnetic valve 14 is provided with a drive unit for controlling the valve opening degree of each valve, and a communication line for transmitting the command of the control unit 16 to each drive unit is wired. A communication line for transmitting the measured temperatures of the temperature sensors 15a to 15d to the control unit 16 is also wired.

[0018] The hot water storage tank 11 is a container that stores the hot water supplied from the heat source unit 2 upward and stores the water supplied from the water supply line downward. Note that there is no partition inside the hot water storage tank 11 to separate the storage of hot water and cold water. As a result of the relatively light hot water moving upward and the relatively heavy water moving downward, hot water accumulates above the hot water storage tank 11 and water accumulates below. Therefore, the height of the hot water and cold water boundary changes at any time according to the remaining amount of hot water.

[0019] The pressure reducing valve 12 reduces the pressure of the high-pressure water supplied from the water supply line and supplies it to the hot water storage tank 11, the mixing valves 13a and 13b.

[0020] The mixing valve 13a mixes the high-temperature hot water supplied from the upper part of the hot water storage tank 11 with the water supplied from the water supply line via the pressure reducing valve 12 to make hot water at a desired temperature and supplies it to the mixing faucet. Similarly, the mixing valve 13b mixes the high-temperature hot water supplied from the upper part of the hot water storage tank 11 with the water supplied from the water supply line via the pressure reducing valve 12 to make hot water at a desired temperature and supplies it to the electromagnetic valve 14.

[0021] For example, when 60°C hot water is supplied from the hot water storage tank 11 and 20°C water is supplied from the water supply line, if the set temperature of the hot water is 40°C, by controlling the valve opening degrees of the respective mixing valves so that the inflow ratio is 50% hot water and 50% water, the temperature of the hot water flowing out from each mixing valve can be made 40°C. For the sake of simplicity, in the following description, the valve opening degree refers to the valve opening degree on the hot water side. Therefore, when it is desired to obtain the valve opening degree on the water side, it may be obtained by subtracting the value of the valve opening degree on the hot water side (0 to 100) from 100.

[0022] The electromagnetic valve 14 switches whether to supply the hot water from the mixing valve 13b to the bath hot water supply line. That is, if the electromagnetic valve 14 is in the open state, hot water is supplied to the bath hot water supply line, and if it is in the closed state, hot water is not supplied to the bath hot water supply line.

[0023] The temperature sensor 15a measures the temperature of the hot water immediately after flowing out of the mixing valve 13a and notifies the control unit 16. The temperature sensor 15b measures the temperature of the hot water immediately after flowing out of the mixing valve 13b and notifies the control unit 16. The temperature sensor 15c measures the temperature of the hot water immediately after flowing out of the hot water storage tank 11 and notifies the control unit 16. The temperature sensor 15d measures the temperature of the water supplied from the water supply pipe and notifies the control unit 16. Hereinafter, the measured temperatures of the temperature sensors 15a to 15d are referred to as Ta’ to Td’, respectively.

[0024] The control unit 16 performs feedback control on the valve opening degrees of the mixing valves 13a and 13b so that the measured temperature becomes the set temperature. For example, in the case of supplying hot water only to the general hot water supply path, the control unit 16 performs feedback control on the valve opening degree of the mixing valve 13a so as to reduce the error ΔTa according to the error ΔTa between the set temperature Ta and the measured temperature Ta’ and the error between the measured temperature Tc’ and the measured temperature Td’. Also, in the case of supplying hot water only to the bath hot water supply path, the control unit 16 performs feedback control on the valve opening degree of the mixing valve 13b so as to reduce the error ΔTb according to the error ΔTb between the set temperature Tb and the measured temperature Tb’ and the error between the measured temperature Tc’ and the measured temperature Td’. Furthermore, in the case of simultaneously supplying hot water to both the general hot water supply path and the bath hot water supply path, the control unit 16 performs the valve opening degree control described with reference to FIGS. 2 and 3 so that the hot water supply temperature of the general hot water supply path with higher priority is stabilized.

[0025] <Mixed faucet 4> The mixed faucet 4 is a faucet that mixes the hot water from the mixing valve 13a and the water from the water supply pipe and supplies it to the faucet or shower in the general hot water supply path, and is operated by the user when finally adjusting the hot water temperature.

[0026] <Mixing valve control during simultaneous hot water supply> When starting the bath water supply during the hot water supply to the general hot water supply line (for example, during a shower), the hot water that has been supplied only from the storage tank 11 to the mixing valve 13a on the general hot water supply line side will also be supplied to the mixing valve 13b on the bath water supply line side. Therefore, during the period until the hot water flows of both sides stabilize, the pressure of the hot water supplied to the mixing valve 13a temporarily decreases. And along with the temporary decrease in the hot water pressure, when the pressure balance of the hot and cold water at the mixing valve 13a is temporarily disrupted and the water pressure relatively increases, the temperature (measured temperature Ta') of the hot water flowing out from the mixing valve 13a temporarily decreases. As a result, the temperature of the hot water downstream of the mixing valve 13a also temporarily decreases, and problems such as a user taking a shower temporarily getting cold water will occur.

[0027] Therefore, in order to avoid such problems, in the water heater 100 of this embodiment, when starting the bath water supply during the hot water supply to the general hot water supply line, as shown in the schematic graph of FIG. 2, the valve opening degree control is implemented to alternately increase the valve opening degree of the mixing valve 13a and the valve opening degree of the mixing valve 13b. Hereinafter, this valve opening degree control will be described in detail.

[0028] First, at the moment when the simultaneous hot water supply is started, the control unit 16 increases the valve opening degree of the mixing valve 13a on the general hot water supply line side to increase the amount of hot water flowing into the mixing valve 13a. Thereby, the mixing ratio of the hot and cold water at the mixing valve 13a can be maintained substantially constant, and the temperature drop of the hot water flowing out from the mixing valve 13a can be suppressed.

[0029] However, when increasing the valve opening degree of the mixing valve 13a to increase the amount of hot water flowing into the mixing valve 13a, as a reaction, the amount of hot water flowing into the mixing valve 13b on the bath water supply line side decreases, and the temperature of the hot water flowing out from the mixing valve 13b will decrease. Therefore, the control unit 16 increases the valve opening degree of the mixing valve 13b to increase the amount of hot water flowing into the mixing valve 13b at the timing when the pressure balance of the hot and cold water at the mixing valve 13a stabilizes, and suppresses the temperature drop of the hot water flowing out from the mixing valve 13b.

[0030] When the valve opening degree of the mixing valve 13b is increased to increase the amount of hot water flowing into the mixing valve 13b, as a reaction, the pressure balance of the hot water at the mixing valve 13a is disrupted again, and the temperature drop of the hot water flowing out of the mixing valve 13a occurs again. However, if the valve opening degree of the mixing valve 13a is increased again, the temperature drop of the hot water flowing out of the mixing valve 13a can be suppressed again. Therefore, when the valve opening degree of the mixing valve 13b is increased, the valve opening degree of the mixing valve 13a may be increased in conjunction with it.

[0031] As can be seen from the above description, when the control unit 16 of this embodiment starts the bath hot water supply during the hot water supply of the general hot water supply path, the control unit 16 performs valve opening degree control that alternately provides a period of increasing the valve opening degree of the mixing valve 13a on the general hot water supply path side and a period of increasing the valve opening degree of the mixing valve 13b on the bath hot water supply path side.

[0032] <Effect of Valve Opening Degree Control in FIG. 2> FIG. 3 is a graph showing an example of the change in the hot water supply temperature on the general hot water supply path side when the valve opening degrees of the mixing valves 13a and 13b are controlled as shown in FIG. 2. The left graph of FIG. 3 is a graph showing the time change of the measured temperature Ta' of the temperature sensor 15a immediately after the mixing valve 13a, and the right graph of FIG. 3 is a graph showing the time change of the temperature of the hot water flowing out from the faucet or shower which is the outlet of the general hot water supply path.

[0033] As shown in the left graph of FIG. 3, for the measured temperature Ta' (the hot water temperature immediately after the mixing valve 13a), a relatively large undershoot occurs immediately after the start of simultaneous hot water supply. However, by the control of increasing the valve opening degree of the mixing valve 13a on the general hot water supply path side at once (see FIG. 2), the undershoot converges rapidly. After that, each time the valve opening degree of the mixing valve 13b on the bath hot water supply path side is increased, a relatively small undershoot occurs, but this undershoot also converges rapidly each time the valve opening degree of the mixing valve 13a on the general hot water supply path side is increased. Therefore, when the valve opening degree control as shown in FIG. 2 is implemented, although small undershoots are repeatedly observed in the measured temperature Ta' (the hot water temperature immediately after the mixing valve 13a), each undershoot can be rapidly converged.

[0034] Here, there is an appropriate pipe distance from the mixing valve 13a to the faucet (or shower). Since the hot water temperature is averaged while flowing from the mixing valve 13a to the faucet (or shower), the undershoot in the temperature of the hot water flowing out from the faucet (or shower) is suppressed to such an extent that it momentarily drops once corresponding to the first relatively large undershoot in the left diagram of FIG. 3, as shown in the right diagram of FIG. 3. Therefore, the user is not affected by the disadvantages associated with simultaneous hot water supply over a long period.

[0035] <Specific Example of Valve Opening Degree Control> Although the outline of the valve opening degree control of this embodiment has been described with reference to FIGS. 2 and 3, the valve opening degree control in FIG. 2 may be implemented as follows.

[0036] <<First Specific Control>> The control unit 16 may set the amount of increase in the valve opening degree of the mixing valve 13a on the general hot water supply path side to be relatively large, and the amount of increase in the valve opening degree of the mixing valve 13b on the bath hot water supply path side to be relatively small. In other words, the control unit 16 may set the amount of increase in the valve opening degree per unit time of the mixing valve 13a on the general hot water supply path side to be relatively large, and the amount of increase in the valve opening degree per unit time of the mixing valve 13b on the bath hot water supply path side to be relatively small.

[0037] By controlling the valve opening degree in this way, it is possible to prioritize maintaining the hot water supply temperature on the general hot water supply path side over the bath hot water supply path side, and to make the temporary decrease in the hot water temperature on the general hot water supply path side smaller.

[0038] <<Second Specific Control>> The control unit 16 realizes an increase in the opening degree of the mixing valve 13a on the general hot water supply path by alternately providing a relatively short time t1 for increasing the opening degree and a relatively long time t2 for maintaining the opening degree. The increase in the opening degree of the mixing valve 13b on the bath hot water supply path may be realized by alternately providing a relatively short time t3 for increasing the opening degree and a relatively long time t4 for maintaining the opening degree. In that case, the control unit 16 may make the control cycle of the mixing valve 13b on the bath hot water supply path longer than the control cycle of the mixing valve 13a on the general hot water supply path. For example, if the time t1 is 0.1 second and the time t2 is 0.9 second, that is, if the control cycle of the opening degree of the mixing valve 13a is 1.0 second, then the time t3 may be set to 0.2 second and the time t4 may be set to 1.8 second, that is, the control cycle of the opening degree of the mixing valve 13b may be set to 2.0 seconds.

[0039] Thereby, while synchronizing the control cycles of the mixing valve 13a and the mixing valve 13b, by changing the valve opening degree of the mixing valve 13a on the general hot water supply path more frequently, the period during which an undershoot of the hot water flowing out from the mixing valve 13a occurs can be made shorter.

[0040] <The effects of this embodiment> As described above, according to the water heater 100 of this embodiment, even when simultaneous hot water supply to the bath hot water supply path is started during hot water supply in the general hot water supply path, the hot water supply temperature in the general hot water supply path can be made more stable.

Embodiment

[0041] Next, with reference to FIGS. 4 and 5, the water heater 100 according to Embodiment 2 of the present invention will be described. Note that the common points with Embodiment 1 will not be described repeatedly.

[0042] In Embodiment 1, as shown in FIG. 2, at the start of simultaneous hot water supply, the valve opening degrees of the mixing valves 13a and 13b were substantially the same. However, in this embodiment, as shown in FIG. 4, at the start of simultaneous hot water supply, the valve opening degree is set such that the mixing valve 13a side is higher and the mixing valve 13b side is lower.

[0043] When the initial value of the valve opening degree is adopted as in this embodiment, the temporary decrease in the hot water pressure generated by the mixing valve 13a on the general hot water supply path at the start of simultaneous hot water supply is smaller than that in the first embodiment. Therefore, as shown in the left figure of Fig. 5, the undershoot occurring immediately after the start of synchronous hot water supply is also smaller than that in the left figure of Fig. 3. Accordingly, the undershoot in the temperature of the hot water flowing out from the faucet (or shower) can also be suppressed to a negligible level, as shown in the right figure of Fig. 5.

Embodiment

[0044] Next, with reference to FIGS. 6 and 7, the water heater 100 according to the second embodiment of the present invention will be described. Note that the description of the common points with the above embodiments will be omitted.

[0045] In the first and second embodiments, as shown in FIGS. 2 and 4, the periods for increasing the valve opening degree of the mixing valve 13a and the periods for increasing the valve opening degree of the mixing valve 13b are provided alternately. However, as in this embodiment shown in FIG. 6, the periods for increasing the valve opening degree of the mixing valve 13a and the periods for increasing the valve opening degree of the mixing valve 13b may overlap.

[0046] When such overlapping periods are provided, the pulling of hot water to the mixing valve 13b side that occurs when the valve opening degree of the mixing valve 13b on the bath hot water supply path is increased can be quickly eliminated by simultaneously increasing the valve opening degree of the mixing valve 13a on the general hot water supply path. Therefore, as shown in the left figure of FIG. 7, the undershoot in the temperature of the hot water flowing out from the mixing valve 13a can be further reduced.

Explanation of Reference Numerals

[0047] 100 Water heater 1 Hot water storage unit 11 Hot water storage tank 12 Pressure reducing valve 13a, 13b Mixing valve 14 Electromagnetic valve 15a, 15b Temperature sensor 16 Control unit 2 Heat source unit 3 Operation unit 4 Mixing faucet

Claims

1. A water heater having a hot water storage unit and a heat source unit, wherein the hot water storage unit comprises a hot water storage tank for storing hot water supplied from the heat source unit, a first mixing valve for mixing the hot water supplied from the hot water storage tank and the water supplied from the outside and flowing out to the general hot water supply path side, a second mixing valve for mixing the hot water supplied from the hot water storage tank and the water supplied from the outside and flowing out to the bath hot water supply path side, and a control unit for controlling the valve opening degrees of the first mixing valve and the second mixing valve, wherein when simultaneously supplying hot water to the general hot water supply path side and the bath hot water supply path side, the control unit alternately starts a first control for increasing the valve opening degree of the first mixing valve and a second control for increasing the valve opening degree of the second mixing valve. The water heater is characterized by this.

2. In the water heater according to Claim 1, the control unit is characterized in that the amount of increasing the valve opening degree of the first mixing valve in the first control is larger than the amount of increasing the valve opening degree of the second mixing valve in the second control.

3. In the water heater according to Claim 1, the first control consists of a first period for increasing the valve opening degree of the first mixing valve and a second period longer than the first period for maintaining the valve opening degree of the first mixing valve, and the second control consists of a third period for increasing the valve opening degree of the second mixing valve and a fourth period longer than the third period for maintaining the valve opening degree of the second mixing valve. The water heater is characterized by this.

4. In the water heater according to Claim 3, the sum of the third period and the fourth period in the second control is larger than the sum of the first period and the second period in the first control. The water heater is characterized by this.

5. In the water heater according to Claim 3, the first period in the first control and the third period in the second control overlap. The water heater is characterized by this.

6. In the water heater according to any one of Claims 1 to 5, the valve opening degree of the first mixing valve at the start of the simultaneous hot water supply is higher than the valve opening degree of the second mixing valve at the start of the simultaneous hot water supply. The water heater is characterized by this.

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