JPH1151479A - Hot water feeding device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent discharging of hot water of high temperature at the time of starting of feeding hot water and enable the temperature of discharged hot water to be controlled at a set temperature as mush as possible. SOLUTION: A hot water feeding passage 10 is provided with a bypass passage bypassing a heat exchanger 14 and mixing fed water at an outlet port of the hot water feeding passage. The hot water feeding passage is provided with a water amount adjusting means at the heat exchanger for controlling an amount of water at the heat exchanger, a temperature of hot water of high temperature within the heat exchanger is decreased at an outlet port of the hot water feeding passage through mixing at the bypass passage at the time of starting of feeding hot water where discharging of hot water of high temperature is expected and concurrently an amount of water at the water amount adjusting means G1 at the heat exchanger is controlled in reference to a deviation between the discharged hot water temperature at the outlet of the hot water feeding passage and the set temperature. After a predetermined period of time after starting feeding of hot water, an amount of water in a water amount adjusting means at the heat exchanger is gradually increased while controlling with the aforesaid deviation along with reduction in temperature within the heat exchanger so as to prevent under-shooting of the temperature of discharged hot water. In turn, an amount of water of the water amount adjusting means at the bypassing side arranged in the bypass passage is gradually increased and similarly the temperature of the discharged hot water is maintained at the set temperature.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a water heater that has a bypass passage and a water flow control valve on the heat exchanger side to eliminate hot water supply at the start of hot water supply and control hot water supply at a set temperature.

[0002]

2. Description of the Related Art In a water heater for supplying hot water in accordance with a set temperature, high-temperature hot water supply is a phenomenon that must be absolutely avoided from the viewpoint of safety. Generally, a water heater performs heat quantity control based on a feedforward temperature obtained from an incoming water temperature, an incoming water quantity, and a set temperature, and further performs heat quantity control based on a feedforward amount based on a deviation between the outlet water temperature and the set temperature.

[0003]

However, if the water in the heat exchanger is warmed to a high temperature for some reason at the start of hot water supply, the hot feed cannot be prevented by the feedforward control and the feedback control. .

[0004] In particular, when hot water supply is started immediately after hot water supply is stopped, the water in the heat exchanger becomes hot due to the amount of heat of the heat exchanger, and high-temperature hot water is generated at the time of re-hot water supply. Further, among water heaters having a combined function having a circulation path for reheating a bathtub, there is a one-can-two-channel water heater in which the water supply path and the circulation path are inserted into a common heat exchanger to reduce the size. In the case of such a water heater, the water in the hot water supply passage passing through the same heat exchanger may rise to near the boiling temperature due to burner combustion during the reheating operation. When the hot water tap is opened and hot water supply is started at that time, the hot water is discharged. Also,
Not only during reheating, but also immediately after reheating and immediately after the hot water supply ends, there is a danger of high-temperature hot water supply.

[0005] Various methods have been proposed for preventing high-temperature hot water supply at the start of hot water supply, but they are not yet control methods capable of preventing satisfactory high-temperature hot water supply. In particular, in the case of the above-mentioned one-can-two-channel water heater, the prevention of high-temperature hot water supply at the time of a hot water supply request during reheating is achieved by controlling the safety more safely because the temperature of the hot water in the heat exchanger is extremely high. A method is desired.

Accordingly, an object of the present invention is to provide a water heater capable of effectively preventing high-temperature hot water supply at the start of hot water supply.

It is a further object of the present invention to provide a water heater that prevents high-temperature hot water supply at the start of hot water supply and that can control the hot water temperature to a set temperature as much as possible.

It is a further object of the present invention to provide a water heater that prevents high-temperature hot water supply at the start of hot water supply and can control the hot water temperature to a set temperature as much as possible in a one-can, two-channel water heater.

[0009]

SUMMARY OF THE INVENTION According to the present invention, a hot water supply path is provided with a bypass passage for bypassing a heat exchanger and mixing an incoming water at an outlet of the hot water supply path. A heat exchanger-side water amount adjusting means for controlling the amount of water is provided, and at the start of hot water supply where hot water is expected to be discharged, the temperature of the hot water in the heat exchanger is lowered at the outlet of the hot water supply channel by mixing from the bypass passage. At the same time, the water amount of the heat exchanger side water amount adjusting means is controlled by a deviation between the outlet temperature of the outlet of the hot water supply path and the set temperature. Thereby, high-temperature hot water is reliably prevented by mixing the incoming water from the bypass passage, and at the same time, the amount of water from the heat exchanger is controlled by the heat exchanger side water amount adjusting means so that the hot water temperature is controlled to the set temperature as much as possible. be able to.

According to the present invention, after a predetermined time after the start of hot water supply, the water amount of the water amount adjusting means on the heat exchanger side is gradually increased while the temperature is being controlled by the above-mentioned deviation in accordance with the decrease in the temperature inside the heat exchanger. Prevent undershoot of tapping temperature. On the other hand, the water amount of the bypass-side water amount adjusting means provided in the bypass passage is gradually reduced, and the tapping temperature is similarly maintained at the set temperature. Eventually, the bypass-side water amount adjusting means is almost closed,
The amount of water from the heat exchanger is controlled according to the required number.

The closing drive of the bypass-side water amount adjusting means is as follows.
The start timing and speed are controlled according to the temperature in the heat exchanger. For example, the closing drive is started at a certain reference temperature. Alternatively, the start timing and the speed of the closing drive of the bypass side water amount adjusting means are controlled in accordance with the flow rate of the hot water supply path. For example, when the flow rate is large, the start timing is early and the speed is also fast. When the flow rate is small, the start timing is late and the speed is also slow.

Further, according to the present invention, when the flow rate of the hot water supply path is large, the amount of heat supplied by the heat supply means is increased, and when the flow rate of the hot water supply path is small, the supply heat amount of the heat supply means is reduced, and Is controlled to be maintained at the set temperature.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. However, the technical scope of the present invention is not limited to the embodiment.

FIG. 1 is a configuration diagram of a water heater according to an embodiment of the present invention. The example of the water heater shown in FIG. 1 is a one-can-two-channel water heater in which a hot water supply path 10 and a circulation path 22 connected to a bathtub 24 pass through a common heat exchanger 14.
The present invention is not limited to a one-can-two-channel water heater, but in the present embodiment, a one-can-two-channel water heater will be described as an example.

Water is supplied from a tap to the hot water supply passage 10, and the hot water supply passage 10 passes through a heat exchanger 14 and is connected to a hot water tap 12. The hot water supply path 10 is a hot water supply path 1 in the heat exchanger 14.
A fixed bypass 16 is provided so that the water in 0 is maintained at a predetermined temperature or higher. Further, the hot water supply path 10 is provided with a variable bypass path 18 that bypasses the heat exchanger.
The variable bypass passage 18 is provided with a bypass-side water flow control valve G2, and the hot water supply passage 10 passing through the heat exchanger 14 is provided with a heat exchanger-side water flow control valve G1. In addition, hot water supply channel 1
At 0, an inlet-side flow sensor FS1 for measuring the amount of incoming water passing through the heat exchanger 14 and the fixed bypass 16 is provided. Further, at the outlet side of the hot water supply path 10, a hot water tap 1
Outlet-side flow sensor FS for detecting the amount of water flowing out of the pump 2
2 are provided. In the hot water supply path 10, an incoming water thermistor Tin for detecting the incoming water temperature and a heat exchange outlet thermistor T for detecting the temperature in the hot water supply path 10 in the heat exchanger 14 are provided.
out, and a tapping thermistor Tmix that detects the water temperature at the outlet of the hot water supply path 10 into which water from the variable bypass path 18 is mixed.

The heat exchanger 14 further passes through a pipe of a circulation path 22 connected to a bathtub 24. The circulation path 22 is connected to a bathtub 24 at a part of a circulation fitting 26. In the circulation path 22, a circulation pump T and a bathtub thermistor Tf for detecting a bathtub temperature are provided. The outlet of the hot water supply path 10 and the circulation path 22 are connected by a pouring path 28. By opening the pouring valve M <b> 2 provided in the pouring channel 28, the hot water in the hot water supply channel 10 is poured into the bath 24 via the pouring channel 28 and the circulation channel 22. As means for supplying heat to the heat exchanger 14, a burner 20 is provided, and a controlled amount of gas is supplied to the burner 20 by controlling the proportional valve M1.

The above-described actuators such as the temperature sensor, the flow sensor, the water amount control valve, and the proportional valve are connected to a control device 30 provided in the water heater. The output from the sensor is supplied to the control device 30, and the control device 30 drives each of the actuators according to a control program stored in a memory (not shown).

In the case of the one-can, two-channel water heater shown in FIG. 1, the water exchanger 10 and the bath circulation path 22 share a common heat exchanger 1.
Pass 4 Therefore, when the burner 20 is burned to perform the reheating operation on the bath side, the water in the hot water supply passage 10 is also burned at the same time. Accordingly, when the hot water tap 12 is opened and a hot water supply request is issued during the reheating operation, high-temperature hot water in the hot water supply passage 10 in the heat exchanger is discharged from the hot water tap 12. Such a phenomenon is called high-temperature tapping and must be particularly avoided from the viewpoint of safety. The problem of high-temperature hot water supply is not limited to the one-can-two-channel water heater, but also occurs when the hot water is restarted immediately after the end of hot water supply in a normal water heater.
Similarly, even in the one-can-two-channel water heater, when the hot water supply request is made immediately after the completion of the bath reheating operation or immediately after the hot water supply operation, the problem of the high-temperature hot water supply also occurs.

In the case of a one-can, two-channel water heater, in the bath reheating operation, the burner 20 is burned to supply heat to the hot water supply passage 10 in the heat exchanger 14, and the heat is transferred to the circulation passage 22 side. Thus, heat supply to the circulation path 22 is performed. In this case, since the water in the hot water supply passage 10 in the heat exchanger is not circulating, the operation of the burner 20 is intermittently operated so that the water in the hot water supply passage 10 does not boil. Therefore, the temperature in the hot water supply path 10 in the heat exchanger rises to near the boiling temperature. Such an increase in the temperature in the hot water supply path in the heat exchanger 14 causes a problem of high-temperature hot water supply when hot water supply is started during the bath reheating operation.

FIG. 2 is a timing chart of basic control at the start of hot water supply in this embodiment. FIG.
The temperature Tout of the heat exchange outlet thermistor for detecting the water temperature of the hot water supply passage 10 in the heat exchanger 14, and (2) the opening / closing control of the heat exchanger side water amount adjustment valve G1 and the bypass side water amount adjustment valve G2. And (3) the tapping temperature T on the outlet side of the hot water supply path 10
mix and (4) show a control method of the proportional valve M1.
The horizontal axis direction in FIG. 2 indicates a time axis.

It is now assumed that a request for starting hot water supply is issued at time t0 during the bath reheating operation. As shown in FIG. 2A, the outlet side temperature Tout of the heat exchanger 14 is shown.
When a hot water supply start request is issued at time t0, the temperature rises rapidly to a high temperature, and then drops after the peak temperature has passed. The peak temperature of the outlet side temperature Tout of the heat exchanger corresponds to the temperature during the intermittent combustion control during the bath reheating operation. In the present embodiment, a predetermined amount of water is supplied from the variable bypass passage 18 to the high-temperature hot water from the heat exchanger 14 so that the hot water in the heat exchanger having the high peak temperature is not directly discharged from the hot water tap 12. Mixing. That is, as shown in FIG. 2 (2), the bypass-side water amount adjusting valve G2
Is almost fully opened from the hot water supply start time t0 to the time t2 to mix a sufficient amount of incoming water into the hot water supply passage 10. The degree to which the opening of the bypass-side water amount adjusting valve G2 is opened is controlled so as to be an amount sufficient to cancel the peak value of the temperature Tout at the heat exchanger outlet.

On the other hand, the heat exchanger-side water amount adjusting valve G1 is squeezed to an appropriate amount so that a large amount of hot water in the heat exchanger 14 is not discharged at the start of hot water supply t0. After that, the heat exchanger-side water flow control valve G1 is controlled in accordance with a deviation between the temperature Tmix detected by the tapping thermistor and the required set temperature Ts. That is, the amount of water is controlled such that the tapping temperature Tmix becomes the set temperature Ts. More specifically, when the tap water temperature Tmix is lower than the set temperature Ts, the heat exchanger-side water amount control valve G1 is controlled so as to increase its opening, and the amount of hot water from the heat exchanger is increased. Is increased. On the other hand, when the tapping temperature Tmix is higher than the set temperature, the opening degree of the heat exchanger-side water amount control valve G1 is controlled to be squeezed.

As described above, from the start of hot water supply t0 to the time t2
Until the first time, the mixing is performed so that the outlet water temperature Tmix does not exceed the set temperature Ts by mixing of the incoming water from the bypass-side water amount control valve. Secondly, the water amount of the heat exchanger-side water flow control valve G1 is adjusted so that the tapping temperature Tmix approaches the set temperature Ts as much as possible.
It is controlled based on the deviation of s.

As shown in FIG. 2A, the outlet temperature Tout of the heat exchanger falls after a certain peak temperature. Accordingly, the tapping temperature Tmix decreases, so that the opening of the heat exchanger-side water amount adjustment valve G1 is controlled so as to gradually open according to the deviation between the tapping temperature and the set temperature. However, the heat exchanger side water flow control valve G1
Is opened, the tapping temperature Tmix cannot maintain the set temperature Ts due to a decrease in the outlet temperature Tout of the heat exchanger. Therefore, in the present embodiment, the opening degree of the bypass-side water amount control valve is controlled so as to gradually decrease from time t2 to time t3. Eventually, at time t3, the bypass-side water amount adjusting valve G2 is almost fully closed, while the heat exchanger-side water amount adjusting valve G1 is adjusted to a water amount corresponding to the required number of water heaters. Therefore, when the flow rate to the heat exchanger is small and the outlet temperature Tout of the heat exchanger gradually decreases, the bypass-side water amount control valve G2 starts to close after the heat-exchanger-side water amount control valve G1 is fully opened. Can also occur.

In the present embodiment, the gas amount of the proportional valve M1 connected to the burner 20 is controlled by feedforward control from the start of hot water supply t0 to the time t3 as shown in FIG. After time t3 after the side water amount control valve G2 is fully closed, the usual control of the combination of feed forward and feedback is performed.
Immediately after the start of hot water supply, the gas supply amount from the proportional valve M1 is made as constant as possible, and the two water flow control valves G1 and G2 are used to prevent high-temperature hot water supply immediately after the start of hot water supply and to control the temperature of the hot water near the set temperature. Further, after the control at the start of tapping by the water flow control valves G1 and G2 is completed, the proportional valve M1 is operated as usual.
Are feedforward and feedback controlled.

FIG. 3 is a timing chart for detailed control of the present embodiment. In the present embodiment,
Bypass-side water flow control valve G2 and heat exchanger-side water flow control valve G
Reference numeral 1 denotes an on-off valve whose opening is linearly controlled by a gear motor or the like. Therefore, the water flow control valves G1, G2
Is controlled by control signals G1 and G2 supplied from a control device 30 including a microcomputer or the like.
The opening is controlled. Therefore, in the timing chart of FIG. 3, the control signal g to the bypass-side water amount control valve G2 is shown.
2 and a control signal g1 for the heat exchanger side water flow control valve G1.
Are respectively shown. Times t0 to t3 shown in FIG. 3 correspond to times t0 to t3 shown in FIG.

Also in FIG. 3, it is assumed that the hot water tap 12 is opened and a hot water supply request is issued at time t0 during the bath reheating operation. When the hot water tap 12 is opened, the outlet side flow sensor FS
2 detects a predetermined amount of water, and control device 30 detects that a hot water supply request has been made. At the start of hot water supply, the bypass-side water amount control valve G2 provided in the variable bypass passage 18
As shown by reference numeral 30 in FIG. 3C, the apparatus stands by while maintaining a relatively large opening. On the other hand, the heat-exchanger-side water flow control valve G1 has a relatively closed position (3 in the figure).
Wait in 2).

At time t0, when hot water supply is started,
As described above, the outlet temperature Tout of the heat exchanger 14 rapidly rises. At the start of hot water supply, the control device 30 supplies a control signal g2 in a direction to open the opening degree to the bypass-side water amount adjusting valve G2. Since the bypass-side water amount control valve G2 is in a relatively open state as shown in FIG.
The full-open state is established in a short time by the drive signal g2. Then, the fully open state is maintained until time t2. By mixing a large amount of incoming water from the variable bypass passage 18 to the outlet of the hot water supply passage, the temperature of the high-temperature hot water from the heat exchanger 14 is reduced, and high-temperature hot water is avoided.

On the other hand, after the start of hot water supply t0, a drive signal g1 corresponding to the difference between the hot water temperature Tmix and the set temperature Ts is supplied to the heat exchanger side water flow control valve G1.
As shown in FIGS. 3 (4) and (5), tapping temperature Tmi
While x is lower than the set temperature Ts, a drive signal g1 for opening the heat exchanger side water flow control valve G1 is supplied, and while the tapping temperature Tmix is higher than the set temperature Ts, the heat exchanger side water flow control valve is turned off. The closing drive signal g1 is supplied. The drive signals g1 and g2 are control signals modulated by, for example, a pulse width modulation method from the control device 30. The strength of the drive signal of the control signal based on the pulse width modulation method is controlled by the duty ratio. Therefore, the control signals g2 and g1 shown in FIGS. 3 (2) and (5) indicate, for example, the average power value of the control pulse signal.

The above-described control of the opening of the heat exchanger side water flow control valve G1 is performed based on the deviation between the tapping temperature Tmix and the set temperature Ts. Here, when the tapping thermistor Tmix is provided on the outlet side of the hot water supply path 10 as shown in FIG. 1, the flow rate to the heat exchanger side water flow control valve G1 is simply determined according to the difference between the tapping temperature Tmix and the set temperature Ts. Is supplied. Alternatively, even when the tap water thermistor Tmix is not provided, the tap water temperature Tmix is calculated by the following equation based on the detection output from the water inlet side flow sensor FS1, the outlet side flow sensor FS2, the water inlet thermistor Tin, and the heat exchange outlet thermistor Tout. Desired.

[0031]

(Equation 1)

The above temperature Tout2 is a temperature at a position where the fixed bypass passage 16 and the hot water supply passage 10 from the heat exchanger 14 join, and the flow rate ratio between the fixed bypass passage 16 and the heat exchanger side hot water supply passage, For example, it is obtained by the above equation (3) by 7: 3.

Returning to the timing chart of FIG. 3, after the outlet temperature Tout of the heat exchanger 14 has passed the peak value at the time t2, the outlet temperature Tout decreases, so that the outlet temperature Tmix and the set temperature Ts The heat exchanger-side water flow control valve G1 controlled by the deviation is controlled so as to gradually increase its opening. Eventually, the heat exchanger-side water amount adjustment valve G1 is almost fully opened.

On the other hand, even if the opening degree of the heat exchanger side water flow control valve G1 is increased due to the decrease in the outlet temperature Tout, the tapping temperature Tm
ix cannot follow the set temperature Ts. Therefore, the control device 30 supplies a drive signal g2 for closing the bypass-side water amount adjusting valve G2 to the valve G2. As a result, the opening of the bypass-side water amount control valve G2 is gradually reduced from time t2,
At time t3, it is fully closed. The timing and drive speed of the timing t2 for closing the bypass-side water amount control valve G2 and the time t3 when it is completed are controlled to optimal values by the control device 30 according to, for example, a decreasing curve of the outlet temperature Tout of the heat exchanger. . Ideally, tap water temperature Tmi
The closing drive of the bypass-side water amount control valve G2 is started so that x maintains the set temperature Ts, and the outlet temperature Tout of the heat exchanger is started.
When the fall from the peak value is completed, the bypass-side water amount adjusting valve G2 is in the fully closed state. After the time t3, the opening degree of the heat exchanger-side water flow control valve G1 is controlled so that the flow rate corresponds to, for example, the required number of water heaters.

From time t3 to time t4 when the flowing water is turned off, as described with reference to FIG.
8 is closed, the proportional valve M1 is controlled by normal feedforward and feedback control, and the tapping temperature Tmi
x is controlled to maintain the set temperature Ts. Eventually,
When the hot-water tap 12 is closed and the running water is turned off, the bypass-side water amount adjusting valve G2 is opened by the control signal g2, returns to the original position of 30 in the state diagram, and stands by. On the other hand, the heat exchanger-side water flow control valve G1 is also driven in the closing direction by the control signal g1, and returns to the state of 32 in the figure and waits.

In the above-described embodiment, the bypass-side water amount control valve G2 uses a motor-driven opening / closing valve that can linearly control the opening degree. It is also possible with an operating, for example, solenoid valve. In this case, as shown in FIG. 3 (7), the solenoid valve G2 is opened after the hot water supply start time t0, and is closed at a predetermined time later than the time t2. When an electromagnetic valve whose ON / OFF is controlled only for the bypass side water amount control valve G2 is used, a slight overshoot occurs in the tapping temperature Tmix, but does not reach a large overshoot immediately after the start of tapping.

[Example of Control at the Start of Mixing] In the embodiment described with reference to FIG. 3, after the start of hot water supply t0, the heat exchanger-side water amount adjusting valve G1 sets the tapping temperature Tmix.
And the set temperature Ts. In this case, in order to achieve the first object of preventing high-temperature hot water supply immediately after the start of hot water supply, the bypass-side water amount adjusting valve G2
Is controlled to be fully open or close to it. Therefore, immediately after the hot water supply start time t0, the hot water temperature Tmix generates an undershoot 34 as shown by the solid line in FIG. In response to the undershoot 34, the control device 30 supplies a drive signal g1 for opening the heat exchanger-side water flow control valve G1. That is, the drive signal g1 as indicated by 35 in FIG. 4 (4) controls the heat exchanger side water flow control valve G1 to increase its opening. By driving the heat exchanger side water amount control valve G1, the tap water temperature Tmix is set.
Generates a large overshoot 36 as shown by the solid line in FIG. This overshoot 36
May be much higher than the set temperature Ts. The overshoot 36 is contrary to the first purpose of preventing hot water supply at the start of hot water supply.

Therefore, in the improved embodiment, during the predetermined time t10 after the start of hot water supply t0, the control of the heat exchanger side water flow control valve G1 is not performed, and the opening of the water flow control valve G1 is half-open. Waiting in the state. As a result, as shown by the broken line in FIG. 4 (3), the tapping temperature Tmix is changed to the hot water supply start t.
After 0, a slightly large undershoot 38 is generated.
Is not performed, the peak temperature of the overshoot 39 that occurs after the tapping temperature Tmix does not greatly exceed the set temperature Ts.

As described above, in the improved embodiment, the feedback control of the heat exchanger-side water amount control valve G1 is not performed immediately after the start of hot water supply. As a result, the occurrence of the excessive overshoot 36 of the tapping temperature Tmix is prevented.

The period t10 during which the feedback control of the heat exchanger side water flow control valve G1 is not performed is, for example, a time when the tapping temperature Tmix is undershoot. More specifically, the tap water temperature 1 from the start of hot water supply t0
It is assumed that Tmix first exceeds the set temperature Ts until time t12. That is, while the first undershoot is occurring, the feedback control to the heat exchanger side water flow control valve G1 is not performed, so that the overshoot 3 in FIG.
6 can be prevented. However, as for the time at which the feedback control of the heat exchanger-side water amount adjusting valve G1 is started, various modified examples can be considered as described later.

FIG. 5 is a timing chart showing another example of control at the start of mixing. In FIG. 4, it has been described that the feedback control of the heat exchanger-side water amount adjustment valve G1 is not performed for a predetermined time t10 from the start of hot water supply t0. The period t10 during which the apparatus waits at a constant opening without performing the feedback control is changed according to various physical quantities.

In the first example, the outlet temperature Tout of the heat exchanger is
The period during which the feedback control is not performed is changed according to the time until the peak value is reached. That is, as shown by the solid line in FIG. 5A, when the time when the outlet temperature Tout of the heat exchanger reaches the peak value is short, the period t14 during which the feedback control is not performed as shown in FIG. Be shorter. Therefore, the feedback control to the heat exchanger side water amount adjustment valve G1 is started from time t15.

On the other hand, as shown by the broken line in FIG. 5 (1), when the time when the outlet temperature Tout of the heat exchanger reaches the peak value is long, the feedback control is not performed as shown in FIG. 5 (5). The period t16 is longer than the period t14. Therefore, the feedback control of the heat exchanger-side water amount adjustment valve G1 is started from time t17. As a result, as shown in FIG. 5 (3), when the outlet temperature Tout of the heat exchanger rapidly rises to a peak value, the tapping temperature Tmix changes as indicated by reference numeral 40 in the figure. On the other hand, when the outlet temperature Tout of the heat exchanger rises slowly as indicated by the broken line, the tapping temperature Tmix changes as indicated by the broken line 42. The change in the outlet temperature Tout of the heat exchanger can be detected by monitoring the temperature Tout detected from the heat exchange outlet temperature thermistor.

On the other hand, when the flow rate detected by the inlet-side flow sensor FS1 is large, the outlet temperature Tout of the heat exchanger rapidly changes as shown by the solid line in FIG. Conversely, when the flow rate of the inlet-side flow sensor FS1 is low, the outlet temperature Tout of the heat exchanger rises slowly as shown by the broken line in FIG. Therefore, the feedback control of the heat exchanger-side water amount adjustment valve G1 is started as early as the time t15 when the flow rate of the inlet-side flow sensor FS1 is large, and the heat exchange is performed when the flow rate of the inlet-side flow sensor FS1 is small. The feedback control of the container-side water amount adjustment valve G1 is started late as at time t17.

Further, the control of the bypass-side water amount adjusting valve G2 in the variable bypass passage 18 is controlled by the outlet temperature Tou of the heat exchanger.
It is preferable to variably control the opening speed according to t or the flow rate of the inlet-side flow sensor FS1. That is, when the outlet temperature Tout of the heat exchanger sharply rises to the peak value, the duty ratio of the drive signal g2 to the bypass-side water amount adjustment valve G2 is increased as shown by the solid line 44 in FIG. Then, the speed at which the water volume control valve G2 is opened is increased. On the other hand, the outlet temperature Tout of the heat exchanger is
5 (1), or when the flow rate of the inlet-side flow sensor FS1 is small, the duty ratio of the drive signal g2 to the bypass-side flow rate control valve G2 is changed to the state shown in FIG. ), As shown by the broken line 46 in
Slow its opening speed.

As described above, the feedback control by the heat exchanger side water amount control valve G1 is not performed for a predetermined period t14 or t16 from the start of hot water supply t0. Therefore, as shown by the broken line 42 in FIG. 5 (3), the tapping temperature Tmix
Is too big on the contrary. Therefore,
As shown by the broken line 46 in FIG. 5 (2), by lowering the opening speed of the bypass side water amount adjustment valve G2, the undershoot of the tapping temperature Tmix can be reduced. That is, it is as shown by the one-dot chain line 46 in FIG. The opening / closing state of the bypass-side water amount control valve G2 in that case is as shown in FIG. 5 (6). When the opening speed of the water flow control valve G1 is increased, the opening is controlled as indicated by the solid line 44. When the opening speed and the closing speed are reduced, the opening is controlled as indicated by the broken line 46 in FIG. Controlled.

In the above-described embodiment, the hot water supply start time t
From 0, the feedback control of the heat exchanger side water flow control valve G1 is not performed for a predetermined period. As a result, the amount of water detected by the inlet-side flow sensor FS1 is extremely small, and so on.
The rise of the outlet temperature Tout of the heat exchanger after the start of hot water supply becomes very slow, and the outlet temperature Tmix becomes lower than the set temperature Ts.
May not be reached. In such a case, as described above, if the feedback control of the heat exchanger side water flow control valve G1 is controlled to start at the time when the tapping temperature Tmix exceeds the set temperature Ts, the tapping temperature Tmix exceeds the set temperature Ts. As a result, the feedback control by the heat exchanger-side water amount adjustment valve G1 is not started.

Therefore, as a modified example of this embodiment,
If the tapping temperature Tmix does not exceed the set temperature Ts within a predetermined reference time, the control device 30 forcibly starts the heat exchanger side water flow control valve G1 feedback control. By doing so, the worst case described above can be avoided.

[Closing drive control of bypass-side water flow control valve] In the description of the basic control in FIG. 2, the heat exchanger-side water flow control valve G1
Was driven in the fully open direction to correspond to the decrease in the heat exchanger outlet temperature Tout, and further, to respond to the decrease in the outlet temperature Tout, to drive the bypass side water amount control valve G2 in the fully closed direction. If the outlet water temperature Tmix falls below the set temperature Ts even when the heat exchanger side water flow control valve G1 is fully opened due to a decrease in the outlet temperature Tout, the drive to close the bypass water flow control valve G2 is performed. Therefore, it is important at which timing to start the closing drive of the bypass-side water amount adjusting valve G2 in order to eliminate the undershoot of the tapping temperature Tout. On the other hand, the timing at which the bypass-side water amount control valve G2 reaches the fully closed state is also important for eliminating undershoot and overshoot of the tapping temperature Tout. If the closing drive speed is too fast, the tapping temperature will overshoot, and if the closing drive speed is too slow, the tapping temperature will undershoot.

FIG. 6 is a timing chart of an example of closing drive of the bypass-side water amount adjusting valve G2. This example is shown in FIG.
As shown in (1), when the amount of water to the hot water supply passage 10 passing through the heat exchanger 14 is large and the outlet temperature Tout of the heat exchanger rises sharply and falls sharply (solid line), the heat exchanger 14 The closing drive of each bypass-side water amount adjusting valve G2 is shown in the case where the amount of water to the hot water supply passage 10 passing therethrough is small and the outlet temperature Tout of the heat exchanger rises slowly and falls slowly (broken line).

In the example of FIG. 6, the heat exchanger-side water flow control valve G1
The opening drive speed of the valve is sufficiently fast, and the bypass-side water amount regulating valve G2
This is a case in which the tapping temperature Tmix can sufficiently follow the vicinity of the set temperature Ts even if is left fully open. Heat exchanger 14
In the case where the amount of water is large (solid line), there is a request to start hot water supply at time t0, and the bypass-side water amount adjusting valve G2 is driven further from the relatively open state to the fully open direction. And
It is fully opened at time t1. On the other hand, the heat exchanger-side water amount adjustment valve G1 is in a relatively closed state, and a large amount of hot water from the heat exchanger 14 is prevented from being discharged. And
By mixing the incoming water from the variable bypass passage 18, high-temperature hot water supply at the start of hot water supply is avoided.

Thereafter, when the outlet temperature Tout of the heat exchanger falls below the peak value, the control device 30 fully opens the heat exchanger side water amount control valve G1 in order to keep the tapping temperature Tmix at the set temperature. Drive in the direction. Then, both the heat exchanger side water amount adjustment valve G1 and the bypass side water amount adjustment valve G2 are fully opened. However, the outlet temperature To of the heat exchanger To
ut decreases, so that the tapping temperature Tmix is as shown in FIG.
As shown by the broken line, the set temperature Ts cannot be maintained and an undershoot occurs.

Therefore, in the present embodiment, the control device 3
0 supplies a drive signal g2 (1) that closes the bypass-side water amount adjustment valve G2 at time t21, and drives the bypass-side water amount adjustment valve G2 to close. Then, at time t31, the bypass-side water amount adjustment valve G2 reaches the fully closed state.

As described above, the closing drive of the bypass-side water amount adjusting valve G2 is started in order to prevent an undershoot of the tapping temperature Tmix due to a decrease in the outlet temperature Tout of the heat exchanger. Therefore, the timing between time t21 and time t31 will be described in detail.

As shown in FIGS. 6 (1) and (2), at time t21 when the outlet temperature Tout of the heat exchanger reaches a certain reference temperature Tx, the closing drive of the bypass-side water amount adjusting valve G2 is started. As described above, the reference temperature Tx1 is equal to the tapping temperature Tm when both the water flow control valves G1 and G2 are fully opened.
ix is the temperature at which the set temperature Ts cannot be maintained. Assuming now that the flow rate of the heat exchanger 14 and the total flow rate of the fixed and variable bypass paths are 50 to 50, the tapping temperature Tm
Since ix is Tmix = (50 × Tout + 50 × Tin) / 100 = (Tout + Tin) / 2, the outlet temperature Tx1 when Tmix = Ts is obtained as Tx1 = 2 × Ts−Tin.

Accordingly, the control device 30 monitors the heat exchanger outlet temperature Tout, and determines the timing tout when Tout = Tx1.
At 21, the closing drive signal g2 of the bypass-side water amount regulating valve G2 is provided.
Supply (1). As a result, it is avoided that the tapping temperature Tmix drops below the set temperature Ts and an undershoot occurs.

On the other hand, at timing t31 when the bypass-side water amount control valve G2 is fully closed, the tapping temperature Tmix must be maintained at the set temperature Ts. Therefore, the heat exchanger side water amount control valve G1 is fully opened and the bypass side water amount adjustment valve G2
Is fully closed, the outlet temperature Tout at which Tmix = Ts
At the timing of (= Tx2), the bypass-side water amount control valve G2
Completes the closing drive. Assuming that the flow rate ratio between the hot water supply path 10 and the fixed bypass path 16 of the heat exchanger is 70:30, Tmix = (70 × Tout + 30 × Tin) / 100. Therefore, when Tmix = Ts, the outlet temperature Tx1 is Tx2. = (10 × Ts−3 × Tin) / 70.

Accordingly, the control device 30 controls the closing drive speed of the bypass-side water amount adjusting valve G2 so that the heat exchanger outlet is completely closed when the outlet temperature Tout of the heat exchanger reaches the fully closed reference temperature Tx2. That is, the control device 30 controls the bypass-side water amount control valve G2 to start the closing operation when the outlet temperature Tout is at the temperature Tx1, and to complete the closing operation when the outlet temperature is at the temperature Tx2.

The heat exchanger 1 shown by a broken line in FIG.
Even when the flow rate to T4 is low and the outlet temperature Tout rises and falls slowly, the control device 30 starts the closing drive of the bypass-side water amount control valve G2 when the outlet temperature Tout is the temperature Tx1 (time t22), At Tx2, control is performed so that the closing drive is completed (time t32). Outlet temperature T
Out rises and falls slowly, so that the closing drive start time of the bypass-side water amount adjusting valve G2 ends at time t2 when the flow rate of the heat exchanger is large and the outlet temperature Tout is steep.
In contrast, when the flow rate is small and the outlet temperature Tout is slow, the time t22 is later. The same applies to the closing drive end timings t31 and t32 of the bypass-side water amount adjusting valve G2.

Here, since it is difficult to predict the timing of closing drive of the bypass-side water amount adjusting valve G2, the closing drive speed is controlled, for example, according to the flow rate of the hot water supply path of the heat exchanger. Alternatively, the closing drive speed is controlled according to the steepness of the outlet temperature Tout of the heat exchanger. This relationship is obtained, for example, by an experiment, and the control device 30 records the relationship table in a built-in memory and uses it for control.

FIG. 7 is a diagram showing the relationship between the closing drive speed of the bypass water flow control valve G2 and the flow rate or outlet temperature of the heat exchanger. As shown in the figure, the closing drive speed is high when the flow rate is high and is low when the flow rate is low. The closing drive speed is large when the outlet temperature Tout is steep, and is small when the outlet temperature Tout is slow.

As shown in FIGS. 6 (3) and 6 (4), the drive signal g2 (1) for the bypass-side water amount control valve G2 in the case of the solid line.
Is the drive signal g2 when the closing drive speed is high
In (2), the driving speed is low. Further, as shown in the figure, the outlet temperature Tout of the heat exchanger decreases, for example, by approximating a negative quadratic curve. Therefore, the closing drive speed is changed to the outlet temperature Tout.
As shown in the figure, the closing drive speed gradually increases with control in accordance with the slope or differential value of. as a result,
Although the flow rate on the heat exchanger side sharply increases, the outlet temperature Tout stabilizes near the above-described temperature Tx2 due to an increase in the feedforward amount.

If the closing drive speed of the bypass-side water amount adjusting valve G2 is too fast, the flow rate on the heat exchanger side suddenly increases, and conversely, the tapping temperature Tmix generates an overshoot. Therefore, the optimal closing drive speed should be selected.

FIG. 8 is a timing chart of another example of the closing drive of the bypass side water amount adjusting valve G2. In the example of FIG. 6, both the heat exchanger side water amount adjustment valve G1 and the bypass side water amount adjustment valve G2 are fully opened, and the bypass side water amount adjustment valve G
2 was driven closed. However, when the water flow control valve is realized by an open / close valve or the like driven by a gear motor, the closing speed of the bypass water flow control valve G2 is increased before the heat exchanger side water flow control valve G1 is fully opened because the drive speed is slow. May need to start. Alternatively, when the flow rate of the heat exchanger is too large and the outlet temperature Tout rises and falls in a very short time, similarly, the bypass side water amount control valve G
In some cases, the closing drive of No. 2 needs to be started early.
The solid line in FIG. 8 shows such a case.

The outlet temperature Tout indicated by the solid line in FIG.
Is the case where the flow rate of the heat exchanger is large. In this case, since the fall of the outlet temperature Tout is steep, it is not enough to start the closing drive after waiting for the outlet temperature Tout to reach the reference temperature Tx1, as shown in FIG.
ix cannot be maintained at the set temperature Ts, and an undershoot may occur as indicated by a broken line. Therefore, in the example of FIG. 8, the closing drive of the bypass-side water amount control valve G2 is started at an early timing t21 when the outlet temperature Tout reaches the temperature Tx10 higher than the reference temperature Tx1. That is, it is as G2 (1) in FIG. 8 (2). And the speed of the closing drive is
As described above, the flow rate of the heat exchanger or the outlet temperature Tout
Is controlled in accordance with the steepness of. Here, the closing drive speed is constant for simplicity.

In the example shown in FIG. 8, when the flow rate of the heat exchanger is small, as indicated by the broken line, the outlet temperature Tout is
Rise slowly and fall. Therefore, the closing drive of the bypass-side water amount adjustment valve G2 can be started after the heat exchanger-side water amount adjustment valve G1 reaches the fully opened state. Therefore, the timing T31 of the start of the closing drive coincides with the timing at which the outlet temperature Tout reaches the reference temperature Tx1. if,
If the tapping temperature Tmix cannot follow the set temperature Ts before the heat exchanger-side water flow control valve G1 reaches the fully closed state, the bypass-side water flow control valve G2 is closed at a timing higher than the reference temperature Tx1. It is necessary to start driving. The outlet temperature Tout in that case is lower than the temperature Tx10 in the case of the solid line.

Therefore, in the example of FIG. 8, when the flow of the heat exchanger is high, the outlet temperature Tout is at a high timing when the closing drive of the bypass-side water amount adjusting valve G2 is started.
When the flow rate of the heat exchanger is small, the outlet temperature Tout is at a lower timing. Also in this case, the timing of starting the closing drive is earlier when the flow rate is high than when the flow rate is low.

FIG. 9 is a timing chart of still another example of the closing drive of the bypass-side water amount adjusting valve G2. This example is also an example of a case where the opening drive of the heat exchanger side water flow control valve G1 cannot be performed in time when the flow rate of the heat exchanger is a large solid line.
In the case of FIG. 8, it is not enough to drive the heat exchanger-side water flow control valve G1 in the fully open direction as the outlet temperature Tout of the heat exchanger falls from the peak value.
In order to prevent the occurrence of undershoot below the set temperature Ts, the timing of starting the closing drive of the bypass-side water amount adjusting valve G2 is advanced.

In the example of FIG. 9, the bypass-side water amount adjusting valve G2
The timing of the start of the closing drive is based on the outlet temperature To
It is assumed that ut reaches the reference temperature Tx1. However, since the tapping temperature Tmix causes an undershoot, the control value of the proportional valve M1 is increased from the time when the outlet temperature Tout exceeds the peak value, as shown in FIG. 9 (3). That is, basically at the time t0 when the hot water supply starts,
The proportional valve M1 is controlled with a substantially minimum feedforward amount. Therefore, the feedforward amount is increased before the control of the combination of feedback and feedforward is performed after the bypass-side water amount control valve G2 is fully closed. Due to this increase, the amount of heat supplied from the burner 20 increases, and the curve of the decrease in the outlet temperature of the heat exchanger becomes slow. As a result, it is possible to prevent the tapping temperature Tmix from falling below the set temperature Ts even if the heat exchanger-side water amount control valve G1 is not fully opened.

Also in the case of the broken line where the flow rate of the heat exchanger is small, the start timing of the closing drive of the bypass side water amount control valve G2 is
It is controlled when the outlet temperature Tout reaches the reference temperature Tx1. In this case, there is no need to increase the control amount for the proportional valve M1. Therefore, the amount of heat supplied to the burner in the case of the broken line is
It is less than the case of the solid line.

Also in the case of FIG. 9, the bypass-side water amount adjusting valve G
The closing drive speed of No. 2 is controlled in the same manner as described above according to the flow rate of the heat exchanger. Also, in the case of FIG. 9, the closing drive start timing of the bypass-side water amount adjustment valve G2 is controlled as shown in FIG. 7 according to the flow rate of the heat exchanger or the steepness of the outlet temperature Tout, as in FIG. is there.

[0072]

As described above, according to the present invention, it is possible to prevent high-temperature hot water supply at the start of hot water supply and to make the hot water temperature as close to the set temperature as possible. Further, in the one-can-two-water supply type hot water supply channel, at the start of hot water supply during the reheating operation, high-temperature hot water can be completely prevented, thereby enabling more safe control.

Further, according to the present invention, the provision of the bypass-side water amount control valve which is driven in the fully open direction at the start of hot water supply can reliably prevent high-temperature hot water supply immediately after the start of hot water supply. Since the timing and speed of driving the water flow control valve in the fully closed direction can be optimally controlled, the occurrence of undershoot or overshoot in the subsequent tapping temperature can be minimized.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a water heater according to an embodiment of the present invention.

FIG. 2 is a timing chart of basic control at the start of hot water supply in the present embodiment.

FIG. 3 is a timing chart of a detailed control of the embodiment.

FIG. 4 is a timing chart illustrating a control example at the start of mixing.

FIG. 5 is a timing chart showing another control example at the start of mixing.

FIG. 6 is a timing chart of an example of closing drive of a bypass-side water amount adjustment valve G2.

FIG. 7 is a diagram showing a relationship between a closing drive speed of a bypass-side water amount control valve G2 and a flow rate or an outlet temperature of a heat exchanger.

FIG. 8 is a timing chart of another example of the closing drive of the bypass-side water amount adjusting valve G2.

FIG. 9 is a timing chart of still another example of the closing drive of the bypass-side water amount adjusting valve G2.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Hot water supply path 14 Heat exchanger 16 Fixed bypass path 18 Variable bypass path 22 Circulation path 24 Bathtub 30 Control device G1 Heat exchanger side water amount control valve G2 Bypass side water amount control valve

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Kikuo Okamoto, Inventor 3-4 Fukamidai, Yamato City, Kanagawa Prefecture Inside Gaster Co., Ltd.

Claims (9)

[Claims] 1. A water heater having a hot water supply passage passing through a heat exchanger, comprising: a bypass passage bypassing the heat exchanger and having a bypass-side water amount adjusting means; and a heat exchange adjusting a water amount passing through the heat exchanger. Water-side water amount adjusting means, at the start of hot water supply, controlling the water amount of the bypass-side water amount adjusting means to a predetermined amount of water, mixing the predetermined amount of incoming water with the outlet of the hot water supply path, and controlling the temperature of the hot water in the heat exchanger. The hot water is lowered at the outlet of the hot water supply path, and after the start of the hot water supply, the amount of water of the heat exchanger-side water amount adjusting means is controlled in accordance with a difference between the outlet temperature of the outlet of the hot water supply path and a set temperature. A controller that controls the closing drive of the bypass-side water amount adjusting means in accordance with the flow rate of the hot water supply channel a predetermined time after the start. 2. The controller according to claim 1, wherein the controller starts closing the bypass-side water amount adjusting means at a first timing when the hot water supply path is at the first flow rate, and the hot water supply path is closed by the second hot water supply path. A water heater characterized in that when the second flow rate is smaller than one flow rate, control is performed such that the closing drive is started at a second timing later than the first timing. 3. The control unit according to claim 1, wherein the control unit performs a closing drive of the bypass-side water amount adjusting unit at a first driving speed when the hot water supply path has a first flow rate.
When the hot water supply path is at a second flow rate smaller than the first flow rate, control is performed such that the bypass-side water amount adjusting unit is closed at a second drive speed lower than the first drive speed. Water heater characterized. 4. A water heater having a hot water supply passage passing through a heat exchanger, wherein: a bypass passage bypassing the heat exchanger and having bypass-side water amount adjusting means; and a heat exchange for adjusting an amount of water passing through the heat exchanger. Water-side water amount adjusting means, at the start of hot water supply, controlling the water amount of the bypass-side water amount adjusting means to a predetermined amount of water, mixing the predetermined amount of incoming water with the outlet of the hot water supply path, and controlling the temperature of the hot water in the heat exchanger. The hot water is lowered at the outlet of the hot water supply path, and after the start of the hot water supply, the amount of water of the heat exchanger-side water amount adjusting means is controlled in accordance with a difference between the outlet temperature of the outlet of the hot water supply path and a set temperature. A controller that controls the closing drive of the bypass-side water amount adjusting means in accordance with the temperature of the heat exchanger after a predetermined time after the start. 5. The control unit according to claim 4, wherein the controller is configured to perform a closing drive of the bypass side water amount adjusting means when the temperature of the heat exchanger reaches the first temperature when the hot water supply path has the first flow rate. Starting, when the hot water supply path is at a second flow rate lower than the first flow rate, when the second temperature lower than the first temperature is reached, starting the closing drive of the bypass side water amount adjusting means. A water heater characterized by the following. 6. The control unit according to claim 4, wherein the control unit performs a closing drive of the bypass-side water amount adjusting unit at a first driving speed when the hot water supply path has a first flow rate.
When the hot water supply path is at a second flow rate smaller than the first flow rate, control is performed such that the bypass-side water amount adjusting unit is closed at a second drive speed lower than the first drive speed. Water heater characterized. 7. A water heater having a hot water supply passage passing through a heat exchanger, wherein: a bypass passage bypassing the heat exchanger and having bypass-side water amount adjusting means; and a heat exchange for adjusting an amount of water passing through the heat exchanger. Device-side water amount adjusting means; heat amount supplying means for supplying heat to the heat exchanger; controlling the water amount of the bypass-side water amount adjusting means to a predetermined amount at the start of hot water supply; At the outlet of the hot water supply path to lower the hot water in the heat exchanger at the outlet of the hot water supply path. A control is performed in accordance with the difference from the temperature, and further, after a predetermined time after the start of the hot water supply, a closing drive of the bypass-side water amount adjusting means is controlled. To supply the amount of heat A water heater comprising: a controller configured to supply the calorie supply means with a second calorie smaller than the first calorie when the hot water supply passage has a second calorie smaller than the first calorie. . 8. The hot water supply path according to claim 1, wherein the hot water supply path passes through a common heat exchanger together with a circulation path connected to a bathtub. A time when the request for starting the hot water supply is issued during the supply of the hot water. 9. The method according to claim 1, wherein the heat exchanger side water amount adjusting means or the bypass side water amount adjusting means is an on-off valve whose opening is controlled by driving a motor. A distinctive water heater.