JPH0827067B2 - Water heater - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a water heater. Specifically, the present invention relates to a bypass mixing type hot water supply device used for dropping hot water into an instantaneous water heater or a bathtub.

[0002]

2. Description of the Related Art FIG. 5 is an overall configuration diagram showing a bypass mixing type hot water supply device 70 disclosed in Japanese Utility Model Laid-Open No. 64-51149. A water inlet pipe 74 and a hot water outlet pipe 75 are respectively connected to the water inlet side and the hot water outlet side of the heat exchanger 73, and a bypass pipe 76 is arranged between the water inlet pipe 74 and the hot water outlet pipe 75 so as to bypass the heat exchanger 73. The bypass pipe 76 is provided with a bypass opening / closing valve (electromagnetic opening / closing valve) 77 for opening / closing the flow path of the bypass pipe 76.

In the water inlet pipe 74, a water temperature sensor 78 is provided upstream of the branch point with the bypass pipe 76, and the heat exchanger 73 is passed downstream from the branch point with the bypass pipe 76. A flow rate sensor 79 for detecting the amount of water is provided. Further, in the hot water outlet pipe 75, a water flow regulator 80 and a hot water outlet temperature sensor 81 for preventing excessive outflow are provided on the downstream side of the confluence with the bypass pipe 76. 7
Reference numeral 2 is a gas burner for heating water passing through the heat exchanger 73, and the combustion capacity of the gas burner 72 is controlled by the proportional control valve 71.

However, when the hot water temperature is set to 50 ° C. or higher, the bypass opening / closing valve 77 is closed, and the proportional control valve 71 controls the combustion capacity of the gas burner 72 by feedforward control (hereinafter referred to as FF control). Hot water of a set temperature is supplied from the pipe end of the hot water outlet pipe 75.

When the set temperature is 50 ° C. or lower,
The bypass opening / closing valve 77 is opened, and from the ratio of the flow rate on the side of the bypass pipe 76 and the flow rate on the side of the heat exchanger 73, which is measured or designed in advance, the amount of water detected by the flow rate sensor 79 is used to obtain the required hot water temperature before mixing (pseudo-setting). Temperature) is calculated, and the required combustion amount is calculated from the required hot water temperature, the incoming water temperature detected by the incoming water temperature sensor 78, and the amount of water detected by the flow rate sensor 79, and the proportional control valve 71 is FF controlled based on this. . Further, feedback control (hereinafter referred to as FB control) may be added to the proportional control valve 71 based on the deviation between the mixed hot water temperature detected by the hot water temperature sensor 81 and the set temperature. In this case, the FF control is performed. It is possible to correct the error between the mixed hot water temperature and the set temperature due to.

In the hot water supply device 70 of such a system, when the set temperature is lower than 50 ° C., the bypass opening / closing valve 7
7 is opened and high-temperature hot water is passed through the heat exchanger 73,
It is possible to prevent low temperature corrosion of the heat exchanger 73, and
The bypass mixing method can handle a large amount of hot water.

[0007]

However, in the hot water supply apparatus as described above, the water inlet pipe and the hot water outlet pipe are always opened, so that heat exchange is performed even when the curran or the like is opened without igniting the bus burner. Water may flow into the container. For example, when the power switch of the hot water supply is turned off or a power switch is opened during a power outage, or when the water pressure drops and the water flows only through the inlet pipe at a flow rate that is less than the minimum operating water volume (MOQ) of the heater. Water flows through the heat exchanger when the gas burner does not ignite and the heat exchanger is not heated.

Therefore, there is a problem that moisture in the atmosphere is condensed and adheres to the fins of the heat exchanger, corrodes the heat exchanger, and shortens the life of the water heater.

The present invention has been made in view of the above-mentioned drawbacks of the conventional example, and has been made for the purpose of preventing low temperature corrosion of the heat exchanger in the hot water supply apparatus.

[0010]

In the hot water supply apparatus of the present invention, a water inlet pipe and a hot water outlet pipe are connected to the water inlet side and the hot water outlet side of the heater, respectively, and the heater is bypassed to bypass the water inlet pipe and the hot water outlet pipe. A normally-open bypass opening / closing valve that is connected to the bypass pipe and is opened / closed according to the set temperature, and is a normally-closed heater-side opening / closing valve downstream of the branch point of the water inlet pipe with the bypass pipe. A hot water supply device provided with a hot water supply device that opens the bypass opening / closing valve and the heater side opening / closing valve to supply hot water, and closes the bypass opening / closing valve and the heater side opening / closing valve to supply hot water. When hot water is supplied and water is stopped from the high-temperature hot water supply, a controller is provided for opening the bypass opening / closing valve at the same time as closing the heater-side opening / closing valve or prioritizing closing of the heater-side opening / closing valve. I am trying.

[0011]

In the water heater of the present invention, since the normally closed heater side opening / closing valve is provided on the downstream side (heater side) of the branch point of the water inlet pipe and the bypass pipe, When the power switch is off, or when the flow rate on the heater side is less than the minimum operating water volume and the heater is not burning, the on-off valve on the heater side is closed and water does not flow to the heater. . Therefore, it is possible to prevent the water from flowing through the heater in a state where the heater does not burn, and the heat exchanger and the like of the heater are corroded by dew condensation, which shortens the life of the water heater.

Further, when supplying hot water with a slow temperature, the bypass opening / closing valve and the opening / closing valve on the heater side are opened, and hot water passing through the heater and water passing through the bypass pipe are mixed to supply the slow temperature hot water. There is. Further, when hot water is supplied, the bypass opening / closing valve is closed and the heater-side opening / closing valve is opened to discharge hot water passing through the heater. Therefore, in any case, high-temperature hot water flows through the heater to prevent low-temperature corrosion of the heater.

Further, when the hot water is stopped while hot water is being supplied, the bypass opening / closing valve is closed at the same time as closing the heater opening / closing valve or prior to closing the heater opening / closing valve. Since it is opened, the heater-side on-off valve and the bypass on-off valve do not close at the same time. Therefore, for example, it is possible to prevent an incomprehensible phenomenon that the hot water is temporarily stopped (for a few seconds) when the currant is closed, and the hot water is stopped after the hot water is again discharged.

[0014]

1 is a schematic sectional view of a hot water supply apparatus A according to an embodiment of the present invention. The heater 1 has a gas burner 3 inside the can body 2.
And the heat exchanger 4 are housed therein, and the gas burner 3 heats the water passing through the heat exchanger 4. A fan motor 5 for supplying air to the gas burner 3 is provided below the gas burner 3, and the air supplied from the fan motor 5 passes through the gas burner 3 and the heat exchanger 4 and then passes through the can body 2
Is exhausted from the exhaust port 6 opened at the upper part of the.

A spark plug 7 and an ignition confirmation frame rod 8 are provided near the crater of the gas burner 3.
Further, the combustion force of the gas burner 3 is controlled by the proportional control valve 10, and the number of gas burners 3 is switched by the capacity switching solenoid valves 11 and 12.
In addition, 9 is a former solenoid valve.

A water inlet pipe 13 connected to city water or the like is connected to the water inlet side of the heat exchanger 4, and a hot water outlet pipe 14 connected to a currant or a shower is connected to the hot water outlet side of the heat exchanger 4. Further, a bypass pipe 15 is arranged between the water inlet pipe 13 and the hot water outlet pipe 14 so as to bypass the heat exchanger 4, and the bypass pipe 15 is a normally open type in which the flow path is fully opened or fully closed. A bypass opening / closing valve 16 is provided.

A filter 1 is provided at the water inlet side terminal of the water inlet pipe 13.
7 is mounted, and a total flow sensor 18 for detecting the total amount of incoming water and an incoming water temperature sensor 19 for detecting the incoming water temperature are provided on the upstream side of the branch portion of the incoming water pipe 13 with the bypass pipe 15. Further, downstream of the branch point of the water inlet pipe 13 with the bypass pipe 15, the normally closed heater-side opening / closing valve 20 and the heat exchanger 4 for fully closing or fully opening the flow path of the water inlet pipe 13 are connected. A heater-side flow rate sensor 21 that detects the amount of water is provided.

A hot water temperature sensor 22 for detecting the hot water temperature of hot water heated by the heat exchanger 4 is provided upstream of the confluence of the hot water discharge pipe 14 with the bypass pipe 15. Further, a mixing temperature sensor 2 for detecting a mixed temperature of the hot water heated by the heat exchanger 4 and the water passing through the bypass pipe 15 is provided on the downstream side of the confluence point of the hot water outlet pipe 14 with the bypass pipe 15.
3 and a water flow controller 24 for preventing overflow.
In addition, 25, 26, and 27 are drain plugs.

The water heater A is controlled by a controller containing a microcomputer. That is, the controller 31 controls the proportional control valve 10, the bypass opening / closing valve 16 and the like according to the detection values of various sensors such as the water temperature sensor 19 and the mixing temperature sensor 23, thereby switching the pipelines and controlling the hot water temperature. I am doing it.

FIG. 2 is a system block diagram showing a configuration for controlling the opening / closing of the bypass opening / closing valve 16 and the heater-side opening / closing valve 20 among the functions of this controller. That is, the set temperature Ts set by the hot water temperature setting device 32, the total flow rate Qt detected by the total flow rate sensor 18, and the heater side flow rate Qh detected by the heater side flow rate sensor 21 are input to the controller 31. The bypass opening / closing valve 16 and the heater-side opening / closing valve 20 are controlled to open / close by the controller 31.

FIG. 3A is a flow chart showing the control procedure of the heater side opening / closing valve 20 by the controller 31. The opening / closing of the heater side opening / closing valve 20 is controlled based on the detection value Qt of the total flow rate sensor 18, and if the total flow rate Qt is a constant value qhi (for example, 3.5 liters / minute) or more, the heater side The on-off valve 20 is opened so that the total flow rate Qt is a constant value qlow (<
qhi; for example, 3.0 l / min), the heater-side on-off valve 20 is closed. Moreover, qlow ≦ Qt <qh
i is a dead zone and has a hysteresis, and prevents the heater-side on-off valve 20 from being opened and closed by fluctuations in the total flow rate Qt. Describing in accordance with the flowchart of FIG. 3A, first, when the curran or the like is opened and water starts flowing into the water inlet pipe 13, the detection value Qt of the total flow rate sensor 18 is compared with qhi and qlow (S41). , S4
3). While the total flow rate Qt <qhi, the heater side opening / closing valve 20 is kept closed (S43, S44), and when the total flow rate Qt increases to Qt ≧ qhi, the heater side opening / closing valve 20 is opened (S42). ). Once the heater side opening / closing valve 20 is opened,
Since the heater-side on-off valve 20 does not close even if the total flow rate Qt becomes smaller than qhi (as long as it does not drop below qlow) (S41, S43), even if the total flow rate Qt fluctuates in the vicinity of qhi, it frequently occurs. The heater side opening / closing valve 20 is not opened / closed. Thus, the heater-side flow rate Qh is the minimum working water amount (hereinafter, MO
If it does not exceed Q), the heater side on-off valve 20 will not open. Therefore, when a low flow rate of water that does not burn the heater 1 flows, the water does not flow to the heat exchanger 4 and the dew condensation of the heat exchanger 4 occurs. Is prevented.

On the contrary, the total flow rate Qt is compared with qhi and qlow even when the curran is closed, and the heater-side on-off valve is maintained during the total flow rate Qt ≧ qlow. 20 is kept open (S42, S43),
When the total flow rate Qt <qlow, the heater-side open / close valve 20 is closed (S44), and the standby state is restored. In this case, too,
When the heater side opening / closing valve 20 is closed, the total flow rate Qt becomes (q
The heater-side on-off valve 20 will not open even if it becomes larger than qlow (unless it becomes higher than hi) (S41, S43).
Therefore, even if the total flow rate Qt fluctuates in the vicinity of qlow, the heater side opening / closing valve 20 is not frequently opened / closed.

Next, FIG. 3B shows a controller 31.
3 is a flowchart showing a control procedure of the bypass opening / closing valve 16 by the opening / closing of the bypass opening / closing valve 16 by detecting a set temperature Ts set by the hot water temperature setting device 32, a detection value of the heater side flow rate sensor 21, and a total flow rate sensor 18. It is controlled based on Qh and Qt. Explaining in accordance with the flowchart of FIG. 3B, first, when the currant or the like is opened and water starts flowing into the water inlet pipe 13, the set temperature Ts set by the hot water temperature setter 32 is a constant temperature To ( For example, it is checked whether the temperature is 50 ° C. or higher (S45). Set temperature Ts
If <To, the bypass opening / closing valve 16 is maintained in the open state (S49).

On the other hand, if the set temperature Ts ≧ To, the heater-side opening / closing valve 20 is opened and the heater-side flow rate sensor 21 can detect the heater-side flow rate Qh, and then the MOQ of the heat exchanger 4 is reached. It is determined whether the determination is on or off (S4
6). There is a hysteresis in the ON / OFF of this MOQ determination, and the heater side flow rate Qh is Hq (for example, 1.
(5 liters / minute) or more, the MOQ is determined to be ON, and when the heater-side flow rate Qh is smaller than Lq (for example, 1.3 liters / minute), the MOQ is determined to be OFF.
The range of q ≦ Qh <Hq is a dead zone. When the MOQ determination of the heater-side flow rate Qh is OFF, it means that the heater-side opening / closing valve 20 has not been opened due to a failure, and therefore the bypass opening / closing valve 16 is not closed but is left open (S49). On the other hand, when the MOQ determination is on, the total flow rate Qt ≧ qlo detected by the total flow rate sensor 18 is further increased.
Confirm that it is w (S47) Bypass on-off valve 16
Is closed (S48).

Even when the currant is closed, it is first determined whether the set temperature Ts is equal to or higher than the predetermined value To or smaller than To (S45). If the set temperature Ts <To,
The bypass opening / closing valve 16 is kept open (S4
9) Return to the standby state.

On the other hand, if the set temperature Ts ≧ To, it is determined whether the MOQ determination is on or off for the heater side flow rate Qh (S46). While the MOQ determination is on and the total flow rate Qt ≧ qlow, the bypass opening / closing valve 16 is kept closed (S46 to S48). When the heater-side flow rate Qh decreases and the MOQ determination is turned off (S46) or the total flow rate Qt <qlow (S47), the bypass opening / closing valve 16 is opened (S49) and the standby state is returned to.

Since the bypass opening / closing valve 16 and the heater side opening / closing valve 20 are controlled to open / close as described above, the water heater A
Are controlled by the controller 31 as follows. First, the case where the set temperature is Ts <To will be described. In the standby state, the heater-side opening / closing valve 20 is closed and only the bypass opening / closing valve 16 is open. Therefore, when the currant or the like is opened, water starts flowing through the bypass pipe 15 to the water inlet pipe 13. When the total flow rate detected by the total flow rate sensor 18 becomes Qt ≧ qhi, the heater side opening / closing valve 20
Is opened, and water begins to flow into the water inlet pipe 13 on the heater 1 side.
Thus, the bypass opening / closing valve 16 and the heater-side opening / closing valve 20
The heater 1 burns in the open state, the heater 1 is FF-controlled and FB-controlled, and hot water of the set temperature Ts is discharged from the currant or the like. Also, if you have squeezed currants,
When the total flow rate becomes Qt <qlow, the heater side opening / closing valve 20 is closed and hot water supply is stopped.

Next, the case where the set temperature Ts ≧ To is described. When the Karan or the like is opened, water starts to flow through the bypass pipe 15, and when the total flow rate Qt ≧ qhi, the heater side opening / closing valve 20 is opened. When the heater-side opening / closing valve 20 is opened, the heater-side flow rate Qh detected by the heater-side flow rate sensor 21 increases, and when the MOQ is turned on, the bypass opening / closing valve 16 is closed. In this manner, the bypass opening / closing valve 16 is closed and the heater-side opening / closing valve 20 is opened.
Are burned, the heater 1 is FF-controlled, and hot water of the set temperature Ts is discharged from the currant or the like.

Further, when the set temperature Ts ≧ To is narrowed down, the curran and the like are closed, and when the total flow rate Qt <qlow, the heater side opening / closing valve 20 is closed and the bypass opening / closing valve 16 is opened at the same time. Alternatively, if the MOQ determination is turned off earlier than the total flow rate Qt <qlow, the heater side opening / closing valve 20 is closed after the bypass opening / closing valve 16 is opened. Therefore, there is no time when the heater-side on-off valve 20 and the bypass on-off valve 16 are closed at the same time, so that the hot water supply from the calan etc. is stopped once, and then the hot water is re-supplied, and finally the hot water stops, so that the phenomenon of smooth stop does not occur. The hot water supply is stopped at.

As described above, the heater 1 for the water inlet pipe 13
When the hot water supply apparatus A having the heater side opening / closing valve 20 on the side is manufactured, the opening / closing control of the heater side opening / closing valve 20 is performed only by the total flow rate sensor 18, and the bypass opening / closing valve 16 is initially set to the heater side flow rate sensor 21. Opening and closing was controlled only by itself. That is, the control flow of the heater side opening / closing valve 20 is the same as that shown in FIG. 3A, but the control flow of the bypass opening / closing valve 16 is as shown in FIG. S37 of the flow
There was no step. Therefore, the set temperature Ts ≧ To
In the case of, when the hot water is supplied and the curran is closed, the MO of the heater side flow rate Qh detected by the heater side flow rate sensor 21 is detected.
After the Q determination was turned off, the total flow rate detected by the total flow rate sensor 18 became Qt <qlow. Therefore, after the heater side opening / closing valve 20 was closed, the bypass opening / closing valve 16 was opened.
As a result, in the process of closing the currant or the like, there was an incomprehensible phenomenon that the hot water stopped once, then the hot water flowed out from the currant or the like, and finally the hot water stopped when the currant or the like completely closed. On the other hand, by adopting the flow shown in FIGS. 3A and 3B, such an incomprehensible phenomenon could be eliminated.

[0031]

In the hot water supply apparatus of the present invention, since the normally closed heater side opening / closing valve is provided on the downstream side (heater side) of the branch point of the water inlet pipe and the bypass pipe, When the power switch of the equipment is turned off or when the flow rate on the heater side is less than the minimum working water volume and the heater is not burning, the heater side on-off valve is closed and water is not flowing into the heater. Not flowing.
Therefore, water is not passed through the heater without burning the heater, condensation on the heat exchanger can be prevented, corrosion inside the heater due to condensation can be prevented, and the service life of the water heater is long-lasting. Can be made.

Further, when the hot water is stopped while hot water is being supplied, the bypass opening / closing valve is closed at the same time as closing the heater opening / closing valve or before closing the heater opening / closing valve. Since it is opened, the heater-side on-off valve and the bypass on-off valve do not close at the same time. So, for example, when hot water is closed, hot water temporarily stops,
It is possible to prevent the incomprehensible phenomenon that the hot water stops after being discharged again, and to stop the hot water smoothly.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing a hot water supply device according to an embodiment of the present invention.

FIG. 2 is a system block diagram showing a control function of a bypass opening / closing valve and a heater side opening / closing valve of the functions of the controller of the water heater.

3 (a) and 3 (b) are flow charts showing a procedure for opening / closing control of a heater-side opening / closing valve and a bypass opening / closing valve in the above-described embodiment, respectively.

FIG. 4 is a flowchart showing a procedure for opening / closing control of a bypass opening / closing valve in a comparative example.

FIG. 5 is a schematic configuration diagram of a hot water supply device according to a conventional example.

[Explanation of symbols]

 1 Heater 13 Inlet pipe 14 Hot water pipe 15 Bypass pipe 16 Bypass opening / closing valve 18 Total flow sensor 20 Heater side opening / closing valve 21 Heater side flow sensor 31 Controller 32 Hot water temperature setting device

Claims (1)

[Claims] 1. A water inlet pipe and a hot water outlet pipe are respectively connected to a water inlet side and a hot water outlet side of the heater, and a bypass pipe is connected to the water inlet pipe and the hot water outlet pipe so as to bypass the heater, and the set temperature is set to the bypass pipe. A hot water supply device with a normally open type bypass opening / closing valve that opens / closes according to the above, and a normally closed type heater side opening / closing valve downstream of the branch point of the water inlet pipe with the bypass pipe. When hot water is supplied, the bypass opening / closing valve and the heater-side opening / closing valve are opened to supply hot water, and when hot water is supplied, the bypass opening / closing valve is closed and the heater-side opening / closing valve is opened to supply hot water. At times, the hot water supply device is equipped with a controller that opens the bypass opening / closing valve at the same time as closing the heating-side opening / closing valve, or prioritizing the closing of the heating-side opening / closing valve.