JP3375749B2 - 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, and in particular, so-called "rear water" in which hot water is temporarily discharged from a tap pipe when hot water is restarted by post-boiling by a heat exchanger when the water heater is stopped. The present invention relates to a water heater capable of eliminating a boiling phenomenon and a so-called undershoot phenomenon in which low-temperature hot water is discharged.

[0002]

2. Description of the Related Art Conventionally, as shown in Japanese Utility Model Publication No. 2-39167, a water heater of this type is provided with a temperature control valve at a connecting portion between a water supply pipe and a bypass pipe, and the temperature control valve is provided immediately after starting hot water supply. The driving speed of the throttle shaft, that is, the time it takes to close the through hole to the bypass pipe of the temperature control valve is changed according to the hot water supply amount, and the mixing time of hot water from the tap pipe and cold water from the bypass pipe is set The hot water temperature was adjusted accordingly. That is, when the hot water supply amount is large, the time until the through hole of the temperature control valve is closed is shortened, and when the hot water supply amount is small, the time until the through hole of the temperature control valve is closed is lengthened.

[0003]

However, in the above-mentioned water heater, the hot water and the water are not always uniformly mixed, and there is a possibility that the hot water discharge temperature may be uneven. In other words, the temperature distribution of the hot water that has accumulated in the equipment immediately before the start of hot water supply is uneven, so even if cold water is mixed from the bypass pipe at the start of hot water supply,
Actually, the fluctuation of the hot water temperature is large and overshoot or undershoot occurs. In general, hot water temperature control such as detecting the hot water temperature and adjusting the amount of gas is used, but such control still cannot deal with uneven temperature distribution of hot water. The present invention is intended to solve the above problems, and an object of the present invention is to provide a water heater that can reduce an overshoot phenomenon and an undershoot phenomenon when hot water is restarted.

[0004]

In order to achieve the above object, the structural feature of the invention according to claim 1 is that a water supply pipe and a tap water pipe are provided with a heat exchanger heated by a heating device interposed therebetween. , In the water heater that heats the water supplied from the water supply pipe through the heat exchanger during the hot water supply operation and supplies the generated hot water to the outside through the hot water discharge pipe, bypasses the heat exchanger and connects the water supply pipe and the hot water discharge pipe. A bypass pipe is provided, and the impeller is rotatably supported in a closed loop pipe that connects the bypass pipe and the heat exchanger, and the impeller is rotated when hot water supply is stopped.
In addition, the rotary drive device for forcibly circulating hot water in the closed loop pipe line is provided, and the impeller detects the water flow amount to the heat exchanger.
It is also used as the impeller of the flow sensor .

[0005]

[0006]

[0007]

[0008]

Further, the structural feature of the invention according to claim 2 is that, in the water heater according to claim 1 , the rotational drive direction of the impeller when the hot water supply operation is stopped depends on water flow during the hot water supply operation. The reason is that the direction of rotation of the impeller is opposite.

[0010]

[0011]

As described above, the invention according to claim 1 is configured, so that when the hot water supply of the water heater is stopped , the impeller is rotated by the rotary drive device so that the water supply pipe, the hot water supply pipe, and the bypass pipe are connected to each other. Hot and cold water can be circulated in the closed loop pipe line including a heat exchanger. With this, the cold water in the water supply pipe and the bypass pipe, the hot water in the hot water discharge pipe, and the high-temperature hot water due to the post-boiling in the heat exchanger are agitated and mixed, and the hot water exchanges heat with the circulation pipe while circulating. Results in a uniform temperature. As a result, the hot water temperature accumulated in the appliance is averaged, and the overshoot or undershoot of the hot water discharge temperature at the start of the next hot water supply is reduced. Furthermore, in the invention of claim 1,
In addition, the impeller of the flow rate sensor is connected to the hot water in the closed loop pipeline.
Since it can be used for water circulation,
The utility value is increased .

[0012]

[0013]

[0014]

[0015]

According to the invention of claim 2 , the hot water supply operation is started while the hot water supply operation is stopped and the impeller is rotationally driven to stir the hot water. Then, the rotation of the rotationally driven impeller suddenly slows down or changes to the opposite direction. Thereby, the start of the hot water supply operation can be easily known, and the rotational drive of the impeller can be immediately stopped.

[0017]

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 schematically shows a water heater according to the first embodiment. The water heater is provided with a water supply pipe P1 connected to a water supply source (not shown) such as water supply.
Is connected to one end of the heat exchanger 10 having fins around it. The other end of the heat exchanger 10 has a hot water outlet pipe P2.
It is connected to the. The heat exchanger 10 is surrounded by a tubular body (hereinafter, referred to as an inner barrel) 20 that forms a combustion chamber R inside, and a gas nozzle 21 is attached to a bottom portion of the inner barrel 20. The gas nozzle 21 is connected to a gas supply pipe PG in which a proportional control valve 22a for adjusting the gas amount and an electromagnetic valve 22b for opening and closing the gas flow path are interposed, and the gas is supplied from a gas supply source (not shown). The burner 26 is supplied. Then, the burner 26 is ignited by igniting by the operation of the igniter 23 in the gas supply state,
The heat exchanger 10 is heated by the combustion of the gas. Then, combustion air is supplied into the combustion chamber R by a fan 24 provided below the inner case 20, and
Combustion exhaust is provided by an exhaust hood 25 provided above the heat exchanger 10.
Is discharged to the outside.

The hot water outlet pipe P2 is connected to an external pipe leading to a hot water tap 12 provided in a bathroom, a kitchen or the like. The hot water outlet pipe P2 is provided with a thermistor 11 for measuring the hot water temperature at a position slightly apart from the heat exchanger 10. Water pipe P1
Between the outlet pipe P2 and the hot water outlet pipe P2, a bypass pipe PB that bypasses the heat exchanger 10 and communicates the two is provided so as to branch from the two. An impeller type flow rate sensor 30 (hereinafter, simply referred to as a flow rate sensor) is provided at a position slightly closer to the heat exchanger 10 than the branch position of the bypass pipe PB of the water supply pipe P1. The flow rate sensor 30, as shown in FIG.
1 and 4 attached to the outer periphery so as to be orthogonal to each other
A single blade 32 is provided. The rotary shaft 31 is rotatably supported on the inner wall of the water supply pipe P1, and the blades 32 are bent in such a shape as to send water to the heat exchanger 10 side when hot water is supplied. Each tip of the blade 32 is magnetized in a state in which N poles and S poles are alternately arranged as shown in FIG. At the outer peripheral position of the water supply pipe P1 provided with the flow rate sensor 30, three Hall elements Ha, Hb, Hc are connected to each other.
They are arranged at 0 ° intervals. The coils Ca, Cb, Cc are arranged on the outer circumference of the flow rate sensor 30 at 120 ° intervals from each other at an intermediate position between the three Hall elements Ha, Hb, Hc.

Next, an electric control device 40 for electrically controlling the operation of the water heater constructed as described above will be described with reference to the drawings. FIG. 4 is a circuit diagram of the device. The electric control unit 40 is provided with a coil drive unit K1 connected in a three-phase star configuration. The coil driving unit K1 is connected to each of the star-shaped branches by one each of the coils Ca, Cb, Cc and NPN type transistors Ta, Tb, Tc whose emitters are grounded. A PNP type transistor To and a DC power source X are sequentially connected to the star-shaped neutral point O. The negative side of the DC power source X is connected to the other end of each star-shaped branch. The electric control unit 40 has three Hall ICs HaI, HbI, HcI connected in parallel, each having Hall elements Ha, Hb, Hc.
A DC power supply Y is connected to C. The output terminal of each Hall ICHaI, HbI, HcI is the above-mentioned NPN.
The base terminals of the type transistors Ta, Tb, and Tc are connected to the rotation pulse input terminal of the control circuit 41 described later. That is, each NPN type transistor Ta, Tb, Tc is turned on by the output from each Hall ICHaI, HbI, HcI, and each coil Ca, Cb, Cc is excited. In addition, each hall ICHaI, Hb
I and HcI convert the rotation of the blade 32 into a rotation pulse and output it to the control circuit 41. Also, PN
The base terminal of the P-type transistor To is connected to the output terminal of the control circuit 41, receives the rotation command signal from the control circuit 41, turns on the transistor To, and causes each star-shaped branch to have the voltage of the power supply X. Is applied.

The control circuit 41 includes a CPU, ROM, RA
It is composed of a microcomputer including M, I / O, etc., and executes a "hot water supply control program I" corresponding to the flowchart shown in FIG. 5 and a "hot water supply control program II" corresponding to the flowchart shown in FIG. The control circuit 41 includes the thermistor 11, the proportional control valve 22a, the solenoid valve 22b, the igniter 23, and the fan 2.
4, a fan motor 24a for driving 4 and a flame detector (not shown), etc. are connected.

Next, the operation of the embodiment configured as described above will be described. When a power switch (not shown) is turned on, the control circuit 40 starts execution of the "hot water supply control program I" at step 50 shown in FIG.
At 1, initialization processing of various variables is performed. Next, in step 52, the presence or absence of water flow is determined. When water is passed through the appliance by opening the hot water tap 12, the blade 32 of the flow sensor 30
Rotates, and the movement of the magnetic pole due to the rotation is caused by Hall elements Ha to H.
c detects, and Hall ICHaI-HcI outputs a rotation pulse signal to the control circuit 41 according to this. If the rotation speed of the flow rate sensor 30 is equal to or higher than the minimum reference rotation speed by this pulse signal, it is determined that water is flowing and the program is executed in step 5
3, the solenoid valve 22b is turned on to supply the gas to the burner 26, and the igniter 23 is operated to ignite the gas to start combustion control. In this embodiment, the opening degree of the proportional control valve 22a is feedback controlled so that the hot water temperature detected by the thermistor 11 becomes a preset control temperature.

Then, in step 54, it is judged whether or not the water is stopped. When water is stopped by closing the hot water tap 12, and the rotation speed of the flow rate sensor 30 drops below the minimum reference rotation speed, it is determined to be “YES” in step 54, the program proceeds to step 55, and combustion control is performed. finish. Further, at step 56, the timer built in the control circuit 41 starts counting for a fixed time t0. Next, in step 57, the energization of the transistor To from the control circuit 41 is started, and further the Hall ICHa
Energization of the coils Ca to Cc is started by I to HcI, and the blades 32 rotate to transfer the water in the water supply pipe P1 to the heat exchanger 10.
The impeller rotating stroke for sending to the hot water outlet pipe P2 and the bypass pipe PB is started.

The operation of the blade 32 will be described with reference to the schematic diagram of FIG. Assuming that the blade 32 is initially in the position shown in FIG. 3A, the Hall ICHbI detects the magnetic pole N and turns on the transistor Tb accordingly. As a result, the coil Cb is excited to the S pole, and the blade of the N pole is moved in the direction of the arrow. Next, as shown in FIG.
CHaI detects the magnetic pole N and turns on the transistor Ta accordingly. As a result, the coil Ca is excited by the S pole, and the blade of the N pole is moved in the direction of the arrow. Next,
As shown in FIG. 3C, the Hall ICHcI detects the magnetic pole N, and accordingly turns on the transistor Tc. As a result, the coil Cc is excited by the S pole to move the blade of the N pole in the direction of the arrow, and the N pole moves in the direction of the arrow. By repeating the operations shown in FIGS. 3A to 3C described above, the blade 32 continuously rotates. The rotation speed of the blades 32 is proportional to the voltage applied to the coils Ca to Cc, but is set lower than the rotation speed of the blades 32 rotated by passing water during hot water supply. The driving rotation direction of the blade 32 is the same as the rotation direction of water flow.

While the blade 32 is rotating, the Hall IC
HaI to HcI continue to output the rotation pulse signal corresponding to the rotation of the blade to the control circuit 41. And step 58
At, it is determined whether the rotation speed N (corresponding to the number of pulse signals) is larger than a predetermined number No set in advance. That is, it is determined whether or not the hot water tap 12 is opened and water is passed during the combustion stop. If N ≦ No, it is determined that the water is not passed, and the program proceeds to step 59 to determine whether or not the timer has finished counting the fixed time t0. If the counting is not finished yet, the program is returned to step 58 based on the judgment of "NO" and continues to monitor whether or not the rotation speed N is changed during the timer counting. Then, when the counting of the constant time t0 is completed, step 5
Based on the judgment of “YES” in 9, the program is moved to step 60, and the control circuit 41 causes the transistor To to pass.
Is turned off. And Hall ICHa ~ H
The energization of the coils Ca to Cc is stopped by cI, and the rotation of the blade 32 is also stopped. Then, the program is returned to step 52 and waits for resumption of water supply. During the above operation, when the hot water tap 12 is opened and the water flow is restarted while the blade 32 is being rotated by the coil energization, the rotation speed N of the blade 32 becomes larger than No. Accordingly, the program is returned to step 53 based on the determination of "YES" in step 58, and the combustion control is restarted.

As described above, according to this embodiment, when the hot water supply operation of the water heater is stopped, the impeller is rotated for a certain period of time t0, and the water supply pipe, the hot water discharge pipe, the bypass pipe, and the heat exchanger are connected to each other. Water can be circulated (counterclockwise in FIG. 1) in the closed-loop pipe line consisting of As a result, the cold water in the water supply pipe and the bypass pipe, the hot water in the hot water discharge pipe, and the high-temperature hot water due to the post-boiling in the heat exchanger are agitated and mixed, so that the closed loop pipe line can have a uniform temperature. it can. Therefore, the hot water temperature staying in the equipment is averaged, and the overshoot or undershoot of the hot water discharge temperature at the start of the next hot water supply is reduced. In particular, when the hot water temperature is detected and the amount of gas is controlled, the hot water temperature hunting is greatly affected by the non-uniformity of the hot water temperature distribution accumulated in the equipment, but the temperature distribution is made uniform as in this embodiment. By doing so, the hot water temperature control becomes easy. In addition, since water is circulated by also using the blades of the flow rate sensor and the Hall element, it can be constructed at low cost and in a small space.

Next, a modified example 1 of the first embodiment will be described with reference to FIG. In the first modification, the flow rate sensor 35 is a blade 36 provided on the outer periphery of the rotary shaft 31.
The number of was changed to 2. In addition, three Hall elements Ha, H
b, Hc and the three coils Ca, Cb, Cc are the same as in the first embodiment. Regarding the driving of the flow rate sensor 35, as shown in FIG.
When the magnetic pole N is detected, the coil Ca is magnetized to the N pole and the blade 36 having the S pole is rotated in the arrow direction.
Next, as shown in FIG. 6B, the Hall ICHcI detects the magnetic pole N, magnetizes the coil Cb to the N pole in response to this, and rotates the blade 36 in the arrow direction. Furthermore, FIG.
As shown in (c), the Hall ICHaI detects the magnetic pole N, and accordingly, the coil Cc is magnetized to the N pole, and the blade 3
Rotate 6 in the direction of the arrow. By repeating the above-described operation of FIGS. 6A to 6C, the blade 36 can be continuously rotated, as in the first embodiment.

Next, a second modification of the first embodiment will be described with reference to FIG. In the second modification, the rotational driving direction of the flow rate sensors 30, 35 by the coils Ca, Cb, Cc is opposite to the rotational direction during water flow. Then, step 58 of the flowchart shown in FIG.
Is changed as shown in FIG. In the modified example 2 configured as described above, when water flow is restarted while the blade is rotationally driven, the rotational speed of the blade decreases or becomes negative, so the control circuit 40 easily shifts to combustion control. can do.

Next, a second embodiment will be described with reference to the drawings. As shown in FIG. 8, the water heater according to the second embodiment has an impeller 71 instead of the impeller-type rotation sensor at a position slightly closer to the heat exchanger 10 than the branch position of the bypass pipe PB of the water supply pipe P1. Is provided. The impeller 71 has a rotating shaft 7
2 and 2 attached to the outer periphery so as to be orthogonal to each other
More than one blade 73 is provided. The rotary shaft 72 is rotatably supported by the inner wall of the water supply pipe P1, and one end thereof extends through the water supply pipe P1 to the outside. An electric motor 74 is provided at the tip of the rotary shaft 72. Has been.
The blades 73 are bent into a shape that sends water to the heat exchanger 10 side when passing water. Further, a water flow switch 75 for detecting the water supply state is provided slightly upstream of the branch position of the bypass pipe PB of the water supply pipe P1. And
The electric motor 74 and the water flow switch 75 are connected to the control circuit 41 as shown by the dotted line in FIG. The rest of the configuration is the same as that of the first embodiment, and the explanation is omitted.

Next, the operation of the second embodiment constructed as above will be described. When a power switch (not shown) is turned on, the control circuit 41 causes the “hot water supply control program I
The execution of “I” is started in step 80 shown in FIG. 9, and various variables are initialized in step 81. Next, in step 82, the presence or absence of water flow is determined. When water is passed through the appliance by opening the hot water tap 12, the water flow switch 75 is turned on, and the control circuit 41 responds accordingly to step 82.
On the basis of the judgment of "YES" at step 83, the program is moved to step 83, the solenoid valve 22b is turned on and the gas is burned by the burner 2.
6, the igniter 23 is operated to ignite the gas, and combustion control is started.

Then, in step 84, it is judged whether or not the water is stopped. When the water flow switch 75 is turned off by shutting off the hot water tap 12 and the water flow switch 75 is turned off, “YE
Based on the determination of "S", the program proceeds to step 85 and the combustion control ends. Further, in step 86, a timer built in the control circuit 41 causes a fixed time t
Counting of 0 starts. Next, in step 87, a motor rotation signal is output, the electric motor 74 starts rotating, the blades 73 rotate, and the water between the water supply points P1 is transferred to the heat exchanger 1.
0 to circulate through the hot water outlet pipe P2 and the bypass pipe PB.

Next, at step 88, the water flow switch 7
On / off of 5 is determined. If the water supply has not been restarted, the program proceeds to step 89 based on the determination of "YES" in step 88, and it is determined whether or not the timer has finished counting a fixed time. If the counting is not finished yet, the program is returned to step 88 based on the determination of "NO", and it is continuously monitored whether or not the water supply is restarted during the timer counting. Then, when the counting of the fixed time is completed, “Y
Based on the determination of "ES", the program is moved to step 90, the electric motor stop signal is output from the control circuit 41, and the rotation of the electric motor 74 is stopped. Then, the program is returned to step 82, and the restart of water supply is awaited.
During the above operation, the blade 36 by the electric motor 74
When the hot water tap 12 is opened and the water flow is restarted during the rotation of, the water flow switch 75 is turned on,
Accordingly, the program is returned to step 83 based on the determination of "NO" in step 88, and the combustion control is restarted.

As described above, also in the second embodiment, as in the first embodiment, when the hot water supply operation of the water heater is stopped, the impeller is rotated for a certain time t0 to supply the water supply pipe and the hot water supply pipe. The water can be circulated in the closed loop pipe line including the bypass pipe and the heat exchanger, and the hot water in the closed loop pipe line can be made to have a uniform temperature. Therefore, the hot water temperature staying in the equipment is averaged, and the overshoot or undershoot of the hot water discharge temperature at the start of the next hot water supply is reduced.

Next, a modified example 3 of the first and second embodiments will be described. In Modification 3, when the hot water in the closed loop pipe is agitated by the impeller, when the hot water temperature drops below a certain value, it is heated by the combustion gas until the hot water temperature rises above a certain value. Alternatively, it is intended to raise the temperature of the hot water to a certain value or more by heating for a certain time. The thermistor 11 is used for temperature detection.
Further, in the first embodiment, as shown in FIG. 10 (a), the hot water temperature is kept at a constant temperature between step 57 and step 58 or between step 58 and step 59 of the flowchart shown in FIG. Step 58a for judging whether or not it is TL or more and step 58 for showing the heat retention combustion routine
b is added. In the second embodiment, FIG.
1 between steps 87 and 88 or between steps 88 and 89 of the flowchart shown in FIG.
As shown in 0 (b), step 88a for determining whether or not the hot water temperature is equal to or higher than the constant temperature TL and step 88b for showing the heat retaining combustion routine are added.

In the modified example configured as described above,
The temperature T of the hot water is a constant value TL due to agitation while the blade is rotating.
When the following conditions are met, it is determined in steps 58a and 88a that "NO" is determined in steps 58b and 8
8b, the combustion gas is used for heating for a certain period of time or until heating to a certain temperature or higher. As a result, during intermittent use in which hot water is supplied again for a short period of time after the hot water supply is stopped, the rising hot water temperature rises quickly and good hot water discharge temperature characteristics can be obtained.

In each of the above embodiments, the number of blades is four or two, but three blades are used.
One to five or more blades may be used. Also, the number of Hall elements and Hall ICs can be changed according to the blade. Further, for detecting the magnetic pole, not only the Hall element but also another type of magnetic sensor can be used. Further, the arrangement and the like of various parts of the water heater shown in each of the above embodiments are examples, and can be changed as appropriate according to the purpose and application of the water heater.

[Brief description of drawings]

FIG. 1 is a front view schematically showing a water heater according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional view schematically showing a state in which an impeller is attached to a water supply pipe of the water heater.

FIG. 3 is an explanatory diagram illustrating an operation of an impeller type flow sensor.

FIG. 4 is a circuit diagram showing an electric control device of the water heater.

5 is a flowchart of a "hot water supply control program I" executed by the control circuit of FIG.

FIG. 6 is an explanatory diagram illustrating an operation of the impeller type flow sensor according to the modified example 1 of the first embodiment.

FIG. 7 is a diagram showing a part of a flowchart which is a modified part of a “hot water supply control program I” according to a second modification of the first embodiment.

FIG. 8 is a front view schematically showing a water heater according to a second embodiment of the present invention.

9 is a flowchart of a "hot water supply control program II" executed by the control circuit of FIG. 4 in the second embodiment.

FIG. 10 is a view showing a modification 3 of the first and second embodiments.
"Hot water supply control program I" executed by the control circuit of
FIG. 7 is a diagram showing a part of a flowchart that is a modified part of “Hot water supply control program II”.

[Explanation of symbols]

10 ... Heat exchanger, 11 ... Thermistor, 12 ... Hot water tap, 2
0 ... Inner body, 21 ... Gas nozzle, 22a ... Proportional control valve, 2
2b ... solenoid valve, 23 ... igniter, 24 ... fan, 24
a ... fan motor, 26 ... burner, 30 ... flow rate sensor,
31 ... Rotating shaft, 32 ... Blade, 35 ... Flow rate sensor, 36 ...
Vane, 40 ... Electric control device, 41 ... Control circuit, 71 ... Impeller, 72 ... Rotating shaft, 73 ... Vane, 74 ... Electric motor,
75 ... Water flow switch, Ca, Cb, Cc ... Coil, H
a, Hb, Hc ... Hall element, HaI, HbI, HcI
... Hall IC, To, Ta, Tb, Tc ... Transistor, P1 ... Water supply pipe, P2 ... Hot water supply pipe, PB ... Bypass pipe, PG
… Gas supply pipe.

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-5-10286 (JP, A) Actually open 63-165442 (JP, U) Actually open 3-13061 (JP, U) Actual Kohei 2- 39167 (JP, Y2) (58) Fields investigated (Int.Cl. ⁷ , DB name) F24H 1/10 302

Claims (2)

(57) [Claims] 1. A hot water produced by providing a water supply pipe and a hot water discharge pipe across a heat exchanger heated by a heating device, and heating water supplied from the water supply pipe during the hot water supply operation through the heat exchanger. In a closed loop pipe line connecting the bypass pipe and the heat exchanger, wherein a bypass pipe that bypasses the heat exchanger and connects the water supply pipe and the hot water pipe is provided to the outside through the hot water pipe. an impeller disposed rotatably journalled in, rotate the same impeller during the hot water supply is stopped, and a rotation drive device for forcibly circulating the hot water of the closed loop conduit, the impeller, the Flow rate to detect water flow to heat exchanger
A water heater characterized by being used as a sensor impeller . 2. The water heater according to claim 1, wherein a rotational drive direction of the impeller when the hot water supply operation is stopped is
Reverse direction of rotation of the impeller due to water flow during hot water supply operation
A water heater characterized by being oriented .