JP2508570B2 - 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. 4 shows a schematic configuration of a conventional bypass mixing type hot water supply apparatus B. In this hot water supply device B, a normally open type bypass side opening / closing valve (electromagnetic opening / closing valve) 53 is provided in the bypass pipe 52 and the bypass pipe 52 of the water inlet pipe 54 connected to the water inlet side of the heat exchanger 51. A normally closed can body side opening / closing valve (electromagnetic opening / closing valve) 55 is provided downstream of the branch point.

Then, when the curran at the end of the pipe is opened,
Water flows only in the bypass pipe 52, the flow rate flowing in the bypass pipe 52 (bypass flow rate) is detected by the flow rate sensor 56, and the can side switching valve 55 is opened and the heat exchanger 51 is opened only when the flow rate Qt becomes a certain flow rate or more. Water flows in. Then, the flow rate sensor 57 detects the flow rate (can flow rate) Qh passing through the heat exchanger 51, and when the flow rate Qh passing through the heat exchanger 51 is equal to or higher than a certain operating flow rate, the gas burner 58 is ignited to set the temperature. Bring out the hot water.

On the other hand, the flow rate Qh of the can is
Gas burner 5
When 8 is extinguished, the can side opening / closing valve 55 is fully closed, and the bypass side opening / closing valve 53 is closed, the bypass opening / closing valve 5
3 is fully open. Reference numeral 60 is a water amount adjusting valve provided in the hot water outlet pipe 59 for preventing overflow.

[0005]

As described above, in the conventional hot water supply apparatus, when the can body flow rate Qh drops below a certain operating flow rate due to the closing of the cullan or the like, the gas burner 58 is used.
Since the can body side opening / closing valve 55 is completely closed immediately after that, even if the currant is opened again immediately after this, the can body side opening / closing valve 55 opens after the water flows to the bypass pipe 52 to some extent, and heat exchange is performed. Since the gas burner 58 burns after the water flows to the vessel 51 to some extent, there is a large time lag from when the canal is opened to when the can body flow rate Qh is confirmed to be equal to or higher than a certain operating flow rate, during which cold water flows out from the currant and the like. There was a problem.

In particular, the inventor of the present invention, in place of the flow rate adjusting valve and the can body side opening / closing valve, has a can body side valve having a flow rate adjusting function in the heat exchanger side flow passage and capable of being fully closed. It is being considered that the water amount adjusting valve and the can body side opening / closing valve are provided as a single valve to prevent excessive outflow. However, when a can body side valve that can be fully closed is used, there is a possibility that the re-hot water discharge characteristic of the hot water supply device may be significantly reduced. In other words, the valve whose flow rate can be adjusted is different from the on-off valve that simply opens and closes the valve, and the valve must be continuously driven by a motor, and this can-side valve is fully closed when there is no combustion. Even if the water is flowing into the bypass pipe due to the opening of the canal or the like and the controller outputs a signal to open the can body side valve, the MOQ can be judged from the fully closed state of the can body side valve (hereinafter called the target opening). It takes a long time to be opened, and there is a possibility that the re-hot water characteristic of the hot water supply device may be significantly deteriorated.

The present invention has been made in view of the above-mentioned drawbacks of conventional examples, and an object of the present invention is to provide a flow path on the heat exchanger side during non-combustion in order to prevent low temperature corrosion of the heat exchanger. It is intended to improve the re-outflow characteristic of a bypass mixing type hot water supply device which is fully closed.

[0008]

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 connect the water inlet pipe and the hot water outlet pipe. A bypass pipe is connected between the bypass pipe and a normally-open bypass-side valve, and the downstream side of the branch point with the bypass pipe of the water inlet pipe and the upstream side of the confluence point of the bypass pipe with the hot water outlet pipe. A normally closed heater-side valve that opens and closes a flow path is provided between the bypass pipe and the heater-side valve that is opened when the flow rate of the bypass pipe is equal to or higher than a certain flow rate. In a bypass mixing type hot water supply device that burns the heater when the flow rate is equal to or higher than the working flow rate, when the flow rate passing through the heater is equal to or lower than the constant working flow rate,
Extinguish the heater while keeping the valve on the heater side open for a certain period of time, and fully close the valve on the heater side after the elapse of the certain period of time.
It is characterized by having a control means .

[0009]

In the hot water supply apparatus of the present invention, the valve on the heater side is kept fully closed during non-combustion, and the valve on the heater side is opened after detecting that a sufficient flow of water is flowing through the bypass pipe. Since it is open, it is possible to prevent cold water from flowing to the heater and causing low temperature corrosion in the heater.

Moreover, when the hot water supply is stopped, the heater-side valve is not immediately closed, but the heater-side valve is kept open for a certain period of time. Simultaneously with the opening of the curran and the like, water flows into the heater and it is determined whether the flow rate is above a certain operating flow rate. If it is above a certain operating flow rate, the heater burns. Therefore, the judgment as to whether or not the bypass flow rate is equal to or more than a certain flow rate, and the opening operation of the heater side valve are omitted, and the hot water at the set temperature can be quickly discharged, and the hot water discharge characteristics at the time of re-melting are improved. be able to.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a schematic configuration diagram of a water heater 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. Further, the combustion force of the gas burner 3 is controlled by the proportional control valve 5.

A water inlet pipe 6 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 7 connected to a pipe terminal device such as a curran or a shower is connected to the hot water outlet side of the heat exchanger 4. Has been done. Further, a bypass pipe 8 is arranged between the water inlet pipe 6 and the hot water outlet pipe 7 so as to bypass the heat exchanger 4,
The bypass pipe 8 is provided with a bypass flow rate sensor 9 for detecting a flow rate (bypass flow rate) flowing through the bypass pipe 8 and a bypass servo valve (bypass side valve) 10. The bypass servo valve 10 adjusts the bypass flow rate to change the mixing ratio of the hot water heated by the heater 1 and the water flowing in the bypass pipe 8 to generate the hot water temperature (mixing temperature) discharged from the hot water pipe 7. The Tm is controlled and the fully open state is possible, and the fully open state is maintained in the non-combustion state of the heater 1.

A can body flow rate sensor 11 for detecting a water flow rate (can body flow rate) Qh of the heat exchanger 4 and a water inlet for detecting a water inlet temperature Tc at a downstream side of a branch portion of the water inlet pipe 6 with the bypass pipe 8. A temperature sensor 12 is provided.

Further, a hot water temperature sensor 13 for detecting the hot water discharge temperature Th of the hot water heated by the heat exchanger 4 and a can body servo valve (heater) are provided upstream of the confluence of the hot water discharge pipe 7 with the bypass pipe 8. A side valve) 14 is provided. This can body servo valve 14
Is the set temperature T when the amount of hot water supply exceeds the capacity of the heater 1.
The can body flow rate Qh is restricted so that hot water of s or less is not discharged, and the fully closed state is also possible. When the heater 1 is not burning, the fully closed state is maintained.

A mixing temperature for detecting the mixing temperature Tm between the hot water heated by the heat exchanger 4 and the water passing through the bypass pipe 8 is provided downstream of the confluence point of the hot water outlet pipe 7 with the bypass pipe 8. A sensor 15 is provided.

The hot water supply device A is controlled by a controller 16 having a microcomputer built therein. That is, the detection signals of the incoming water temperature sensor 12, the hot water temperature sensor 13, the mixing temperature sensor 15, the can body flow rate sensor 11, and the bypass flow rate sensor 9 are input to the controller 16, and the controller 16 is based on these detection signals. As will be described later, the bypass servo valve 10, the can body servo valve 14, and the proportional control valve 5 are controlled.

FIG. 2 is a flow chart showing a control procedure for starting or stopping hot water discharge of the functions of the controller 16. In this water heater A, when the operation switch is turned off (NO in S21), the can body servo valve 14 is fully closed and the bypass servo valve 1
The operation is stopped in the state where 0 is fully opened (S22), and cold water is prevented from flowing to the heat exchanger 4.

Therefore, even when the operation switch is turned on (YES in S21), the can body servo valve 14 is initially used.
Is completely closed, and the bypass servo valve 10 is fully open. In this state, when the terminal of the hot water outlet pipe 7 is opened, the bypass servo valve 10 is fully opened so that water flows through the bypass pipe 8 and the bypass flow rate Qc is detected by the bypass flow rate sensor 9. Next, it is judged whether or not the detected bypass flow rate Qc is equal to or higher than the constant flow rate Qn (S23). At this time, since the fully closed delay timer, which will be described later, is counting up, the system waits until the bypass flow rate Qc becomes the constant flow rate Qn or more (S23, S36), and when the bypass flow rate Qc becomes the constant flow rate Qn or more, the can body servo valve. 14
Is opened (S24).

When the can body servo valve 14 is opened, water flows through the heat exchanger 4, so that the can body flow rate sensor 11 detects the can body flow rate Qh, and it is determined whether or not the MOQ is off (S25). The method of determining the MOQ is to turn on when the can body flow rate Qh is equal to or higher than the constant working flow rate Qm, and turn it off when the can flow rate Qh is below. Alternatively, when the can body flow rate Qh is equal to or less than the constant operation flow rate Qm, it is determined that the MOQ is off, and when it is equal to or more than the constant operation flow rate (Qm + α), the MOQ is on, and a dead zone having a width of α may be provided. It should be noted that the determination as to whether or not the flow rate is equal to or higher than the constant flow rate Qn may be provided with a dead zone or hysteresis as in the MOQ determination.

In the MOQ judgment, when it is judged that the MOQ is on, the gas burner 3 is ignited and the normal hot water supply operation is carried out (S34). For example, based on the can body flow rate Qh detected by the can body flow rate sensor 11, the incoming water temperature Tc detected by the incoming water temperature sensor 12, and the bypass flow rate Qc detected by the bypass flow rate sensor 9, the water passing through the bypass pipe 8 is detected. The amount of heat required for tapping hot water having a tapping temperature Th to be the set temperature Ts after mixing is calculated from the heat exchanger 4, and proportional control is performed so that the amount of heat supplied to the heat exchanger 4 becomes equal to the calculated amount of heat. The valve 5 is feedforward controlled. Further, according to the deviation between the mixing temperature Tm detected by the mixing temperature sensor 15 and the set temperature Ts, the bypass servo valve 10 is feedback-controlled in a direction to reduce the deviation. Furthermore, heater 1
If the mixing temperature Tm does not reach the set temperature Ts even if the combustion capacity of the heater 1 is maximized, a large flow rate of water that exceeds the combustion capacity of the can body servo valve 14 is squeezed to reduce the can body flow rate Qh. Restriction (prevention of excessive outflow) and supply of hot water at the set temperature Ts. During this normal hot water supply operation, the fully closed delay timer is always set to t2 = 0 (S35).

On the other hand, in the MOQ determination, when it is determined that the MOQ is off (in this case, the valve closing delay timer counts up in S26), the bypass servo valve 10 is immediately fully opened and the can body servo is performed. The valve 14 is fully closed (S28) to prevent the cold water from continuing to flow to the heat exchanger 4.

In this way, it is judged that the bypass flow rate Qc is equal to or higher than the constant flow rate, and the can body flow rate Qh is equal to or lower than the constant operation flow rate (or MOQ is off). As a result, the bypass servo valve 10 is fully opened, and the can is opened. When the body servo valve 14 is fully closed, it is checked again whether the bypass flow rate Qc is equal to or higher than a constant flow rate (S29). If the bypass flow rate Qc is lower than the constant flow rate, the state is maintained.

On the other hand, if the bypass flow rate Qc is equal to or greater than the constant flow rate Qn, the open hold timer is set to t1 = 0 and started (S30), and the open hold timer counts up at t1 = T1. The can body servo valve 14 is kept fully open, the can body flow rate Qh is detected, and it is checked again whether or not the MOQ is off (S31 to S33). This fixed time T
When the MOQ is turned on within 1, the gas burner 3 is ignited and the normal hot water supply operation is performed (S34).

On the other hand, the can body servo valve 14 for a fixed time T1.
When the MOQ is not turned on even when the open holding state is held and the open holding timer counts up (S33), steps S28 to S33 are repeated.

When the can body servo valve 14 is opened, the valve must be driven by the motor from the fully closed state to the target opening, so that it takes time for the can body servo valve 14 to open to the target opening. For this reason, when the valve drive speed of the can body servo valve 14 is slow, the determination processing of S23 to S25 is
Since the can body servo valve 14 is not sufficiently opened at the time of MOQ determination, the MOQ is turned off, and the can body servo valve 14 is closed before the can body servo valve 14 is fully opened (S28). Therefore, even if the flow rate passing through the bypass pipe 8 is equal to or higher than the predetermined flow rate, the can body flow rate Qh is equal to or lower than the constant operation flow rate, and M
When the OQ is not turned on, as in S30 to S33, the can body servo valve 14 is held in the open state for a certain period of time, and the MOQ determination is performed after the can body servo valve 14 reaches the target opening degree.

Next, the processing when the hot water supply apparatus A shifts from the hot water supply operation to the hot water supply stop will be described. Now, considering the hot water supply apparatus A in the normal operating state (S34), the bypass flow rate Qc is decreased due to the closing of the pipe end or the like, and when the bypass flow rate Qc becomes equal to or less than the constant flow rate Qn (S23), the valve is fully closed. Since the delay timer will not be reset (S35),
The fully closed delay timer starts counting from t2 = 0.
Therefore, the fully closed delay timer does not count up (S36) to jump to step 25 (S25). At this time, since the can body flow rate Qh also decreases and the MOQ is turned off (S25), the fully closed delay timer is t2 = T2.
The can body servo valve 14 is stopped and kept in the open state until the count is incremented by, and the bypass servo valve 10 is kept in the standby position for preparing hot water again (S26, S2).
7). The standby position of the bypass servo valve 10 may be a valve position when the MOQ is off, or may be a valve position that provides a target distribution ratio between the bypass flow rate and the can body flow rate. When the currant or the like is opened again within the fixed time T2, the can body servo valve 14 is held in the open state during this period, and the can body servo valve 14 is also bypass servo valve 10.
Since it is maintained almost in the state of tap water, water immediately flows into the heat exchanger 4 and it is determined whether the MOQ is off (S2).
5) If the MOQ is on, the normal combustion state (S34) is set. Therefore, when the currant or the like is opened, hot water of the set temperature is promptly discharged. Therefore, even when the valve drive speed of the can body servo valve 14 is slow, the hot water of the set temperature can be quickly discharged regardless of the valve drive speed of the can body servo valve 14, and the re-melting property can be improved. You can

On the other hand, the open hold timer counts up without turning on the MOQ within the fixed time T2 (S26).
Then, the can body servo valve 14 is completely closed, and the bypass servo valve is fully opened (S28).

FIG. 3 is a flow chart showing a control means for starting or stopping tapping in another embodiment of the present invention. The water heater A of the second embodiment
Since the configuration is the same as that shown in FIG. 1, description will be given using the reference numerals assigned to the respective constituent elements in FIG.

In this water heater A, when the operation switch is turned off (NO in S36), the can body servo valve 14 is fully closed and the bypass servo valve 10 is fully opened. The operation is stopped (S40) to prevent cold water from flowing to the heat exchanger 4.

When the operation switch is turned on (in S36
In the case of (YES), since the can body servo valve 14 is completely closed at first and the bypass servo valve 10 is fully open, when the operation switch is turned on, it is determined that the MOQ is off (S37), and the MOQ is fully closed. Delay timer counts up (S3
8), the can body servo valve 14 is kept fully closed and the bypass servo valve 10 is kept fully open (S41, S).
42).

In this state, the bypass servo valve 10 is fully opened, so when the end of the outlet pipe 7 is opened, water flows into the bypass pipe 8 and the bypass flow rate Qc detected by the bypass flow rate sensor 9 is reached. Is equal to or higher than a constant flow rate Qn (S42). If the constant flow rate is equal to or higher than Qn, the open hold timer is set to t1 = 0 to start (S43) and the can body servo valve 14 is opened (S44). ), The can body servo valve 14 is kept open until the open hold timer counts up at t1 = T1 (S
44, S46). In addition, when the bypass flow rate Qc is equal to or higher than a predetermined flow rate, it is determined that the bypass flow rate Qc is equal to or higher than the constant flow rate Qn, and if it is equal to or lower than the constant flow rate Qn, it is not equal to or higher than the constant flow rate. However, if the bypass flow rate Qc is equal to or higher than the constant flow rate Qn with hysteresis, the flow rate is equal to or higher than the constant flow rate, and the constant flow rate (Qn-β).
If it is below, it may be determined that the flow rate is not above a certain level.

When the bypass flow rate Qc becomes equal to or higher than the constant flow rate Qn and the can body servo valve 14 is opened (S44), water flows to the heat exchanger 4, so that the can body flow rate sensor 11 detects the can body flow rate Qh. , MOQ off is determined (S45). The method of determining the MOQ is to turn on when the can body flow rate Qh is equal to or higher than the constant working flow rate Qm, and turn it off when the can flow rate Qh is below. Alternatively, when the can body flow rate Qh is equal to or less than the constant operating flow rate Qm, it is determined that the MOQ is off, and when it is equal to or more than the constant operating flow rate (Qm + α), the MOQ is on, and a dead zone having a width of α may be provided. The same applies to the determination of MOQ in step 37 (S37).

If the MOQ is turned on before the open hold timer counts up at t1 = T1,
The gas burner 3 is ignited to perform a normal hot water supply operation (S4
7). For example, based on the can body flow rate Qh detected by the can body flow rate sensor 11, the incoming water temperature Tc detected by the incoming water temperature sensor 12, and the bypass flow rate Qc detected by the bypass flow rate sensor 9, the water passing through the bypass pipe 8 is detected. The amount of heat required for tapping hot water having a tapping temperature Th to be the set temperature Ts after mixing is calculated from the heat exchanger 4, and proportional control is performed so that the amount of heat supplied to the heat exchanger 4 becomes equal to the calculated amount of heat. The valve 5 is feedforward controlled. Further, according to the deviation between the mixing temperature Tm detected by the mixing temperature sensor 15 and the set temperature Ts, the bypass servo valve 10 is feedback-controlled in a direction to reduce the deviation. Furthermore, if a large flow rate of water that exceeds the combustion capacity of the heater 1 flows and the mixing temperature Tm does not reach the set temperature Ts even if the combustion capacity of the heater 1 is maximized, the can body servo valve 14 is throttled. The can flow rate Qh is limited (prevention of excessive outflow), and hot water of the set temperature Ts is supplied. After the combustion is started, the MOQ is turned on in step 37 (S37), so the combustion state is maintained without performing the processes of S38 to S39 and S41 to S46 (S37 → S4).
7). During this normal hot water supply operation, the fully closed delay timer is always set to t2 = 0 (S48).

On the other hand, the can body servo valve 14 for a fixed time T1.
If the MOQ does not turn on even when the is held open, and the open hold timer counts up (S46),
Immediately, the bypass servo valve 10 is fully opened and the can body servo valve 14 is fully closed (S41) to prevent the continuous flow of cold water to the heat exchanger 4.

Next, the processing when the hot water supply apparatus A shifts from the hot water supply operation to the hot water supply stop will be described. Now, considering the hot water supply device A in the normal operating state (S47), when the canal flow at the pipe end is closed and the can body flow rate Qh decreases, and the MOQ is turned off (S37), the fully closed delay timer is reset. (S48) is not performed, so the fully closed delay timer is t2.
Start counting from = 0. Then, the can body servo valve 14 is stopped and kept open and the bypass servo valve 10 is kept at the standby position for re-hot water until the fully closed delay timer counts up at t2 = T2 (S).
38, S39). The standby position of the bypass servo valve 10 may be a valve position when the MOQ is off, or may be a valve position that provides a target distribution ratio between the bypass flow rate and the can body flow rate. When the currant is opened again within the fixed time T2, the can body servo valve 14 is held in the open state during this time, and moreover, the can body servo valve 14 and the bypass servo valve 10 are maintained substantially in the state of tapping. Because it has been
Immediately, water flows into the heat exchanger 4 and it is determined whether the MOQ is off (S37). If the MOQ is on, the normal combustion state (S47) is set. Therefore, when the currant or the like is opened, hot water of the set temperature is promptly discharged. Therefore, the can body servo valve 1
Even if the valve drive speed of No. 4 is slow, the hot water having the set temperature can be promptly discharged regardless of the valve drive speed of the can body servo valve 14, and the re-melting characteristic can be improved.

On the other hand, the fully closed delay timer counts up without turning on the MOQ within a fixed time T2 (S3
8) Then, the can body servo valve 14 is completely closed, the bypass servo valve is fully opened (S41), and cold water is prevented from flowing to the heat exchanger 4.

In the control method shown in FIG. 2, although the bypass flow rate Qc is equal to or more than a certain flow rate, the MO
When Q does not turn on, the can body servo valve 14 is kept open for a certain period of time until the open hold timer counts up, and it is monitored whether the MOQ turns on.
On the other hand, in the control method shown in FIG. 3, when the bypass flow rate Qc becomes equal to or higher than the constant flow rate, the can body servo valve 14 is kept open for a predetermined time from the beginning and the MOQ is turned on. It is determined whether or not it is possible to simplify the processing as compared with the control method of FIG. 2 and reduce the redundancy of the processing procedure.

In each of the above-mentioned embodiments, the servo valve whose flow rate is adjustable is used as the can body side valve and the bypass side valve.
The flow rate adjusting valve for preventing overflow and the can side valve may be separate, and the can side valve and the bypass side valve may be open / close valves.

[0039]

According to the present invention, in a bypass mixing type hot water supply device in which the heater side valve is fully closed during non-combustion to prevent low temperature corrosion of the heater, within a certain time after hot water supply is stopped. It is possible to improve the hot water re-flowing property, and it is possible to quickly discharge hot water at the set temperature.
In particular, when the heater side valve is provided with the function of adjusting the flow rate to prevent overflow in addition to the function of fully closing the flow path on the side of the heater, the effect of improving this re-melting property is very excellent. It becomes a thing.

[Brief description of drawings]

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

FIG. 2 is a flowchart showing a control procedure for starting or stopping hot water discharge in the embodiment.

FIG. 3 is a flowchart showing a control procedure for starting or stopping tapping in another embodiment of the present invention.

FIG. 4 is a schematic configuration diagram of a hot water supply device according to a conventional example.

[Explanation of symbols]

 1 Heater 6 Inlet pipe 7 Hot water pipe 8 Bypass pipe 9 Bypass flow sensor 10 Bypass servo valve 11 Can body flow sensor 14 Can body servo valve 16 Controller

Claims (1)

(57) [Claims] 1. A water inlet pipe and a hot water outlet pipe are connected to a water inlet side and a hot water outlet side of a heater, respectively, and a bypass pipe is connected between the water inlet pipe and the hot water outlet pipe so as to bypass the heater, and the bypass pipe is connected to the bypass pipe. A normally open type bypass valve is provided to open and close the flow path between the downstream side of the branch point of the water inlet pipe and the upstream side of the confluence point of the hot water outlet pipe with the bypass pipe. A heater-side valve is provided, and the heater-side valve is opened when the flow rate passing through the bypass pipe is equal to or higher than a certain flow rate, and the heater is burned when the flow rate passing through the heater is equal to or higher than a constant working flow rate. In the bypass mixing type hot water supply device, when the flow rate passing through the heater is equal to or less than the constant operation flow rate, the heater is extinguished while keeping the heater side valve open for a certain time, fully closed system the heater side valve after a predetermined time has elapsed Water heater, characterized in that it comprises means.