JPS6131388B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a combustion device control circuit for a hot water storage type water heater employing a natural circulation method.

In this type of hot water storage type water heater, water or low-temperature water at the bottom of the hot water storage tank is heated via a heat exchanger and circulated as high-temperature hot water to the top of the hot water storage tank, where hot water at a constant temperature is gradually stored from the top of the tank. this is,
This is due to the natural circulation force generated by the head pressure and temperature difference between the inlet and outlet of the heat exchanger.

In addition, the circulation pipe downstream of the heat exchanger is equipped with a thermovalve whose opening area increases or decreases depending on the high-temperature hot water passing through.When the water temperature rises, the opening area increases and the flow rate increases, and when the water temperature decreases, it decreases. By reducing the flow rate, hot water at a substantially constant temperature is supplied to the upper part of the tank. Furthermore, a thermistor is installed at the bottom of the tank to monitor the temperature of the hot water flowing into the heat exchanger. Since this uses natural circulation power, the amount of circulation may decrease and the amount of combustion may become larger than the amount of heat exchanged. If this condition continues, boiling will occur within the heat exchanger and have a negative impact on the heat exchanger. Therefore, in order to prevent this, the thermistor detects when the water temperature exceeds a predetermined value and stops combustion in the combustion device.

However, in conventional devices, if the thermistor fails and combustion does not stop, or even if the thermistor is normal, the heat exchanger or thermovalve is clogged and the flow of hot water becomes slow, and the heat exchange is stopped. The drawback was that even if boiling occurred inside the vessel, there was nothing to indicate this, so detection was inevitably delayed.

The present invention was made in view of the above circumstances, and
A hot water supply system that eliminates the drawbacks of the conventional hot water supply system by installing an abnormal overheat prevention sensor on the downstream side of the heat exchanger in the circulation pipe to detect the temperature of hot water flowing out of the heat exchanger and notifying abnormal overheating, and by providing an alarm device to notify the abnormality. The purpose is to provide a combustion device control circuit for a combustion engine.

Hereinafter, one embodiment of the present invention will be described based on the drawings.

In the circuit surrounded by the dashed line in Figure 1, A
is a vaporization heater protection circuit, B is a vaporization heater temperature control circuit, C is an electromagnetic pump drive frequency control circuit, D is an ignition detection circuit, E is an electromagnetic pump drive pulse width control circuit, F is a timing signal output circuit, G
is a sequence timer, H is a reset circuit,
Timing signal output circuit F and sequence timer G
and reset circuit H constitute a sequence logic circuit. I is a corrosion prevention and water detection circuit, J is a boiling detection circuit, and K is a hot water temperature detection circuit, whose output is
The signal is input to the timing signal output circuit F by the I' circuit configuration.

Next, in the vaporization heater protection circuit A,
4, 5, 7, and 8 are fixed resistors, and 6 is a comparator. The resistor 8 is a feedback resistor, the resistor 7 is a pull-up resistor, and the resistor 200 is an input resistor.

In the vaporization heater temperature control circuit B, 75 is a thermocouple element, 76, 91, 94, 9
7, 103, 203, 211 are capacitors, 7
7, 78, 79, 93, 96, 98, 99, 10
0,101,104,105,107,108,
109, 202, 204, 207, 209, 21
0 is a fixed resistance, 201 is a variable resistance, 90, 92,
205 and 206 are diodes, 102 is a room temperature correction thermistor, 95 and 106 are operational amplifiers, and 208 is a comparator. Note that the diodes 90 and 92 are used to protect the input of the operation amplifier 95, the resistor 96 and capacitors 94 and 97 are used to prevent the operation amplifier 95 from oscillating, and the capacitors 76 and 103 are used as the noise absorbing diode 20.
5, 206 and resistors 109, 204 are for preventing latch-up due to negative voltage being applied to the input of comparator 208 and comparator 6 in evaporative heater protection circuit A, capacitor 203 is for preventing chattering, resistor 210 is for pull-up, Resistors 93, 107, and 209 are for feedback.

In the electromagnetic pump drive frequency control circuit C, 11, 13, 14, 16, 17, 18, 2
1, 22, 24, 26, 28, 29, 30, 3
1, 35, 36, 41 are fixed resistors, 23, 25 are variable resistors, 12, 110 are diodes, 9, 19
is a constant voltage diode for capacitor protection, and 34 is a constant voltage diode for capacitor protection.
PUT, 111 is a burner section, 247 is a flame current detection electrode, 10, 15, 20, 32, 33, 37 are capacitors, 27, 38, 39 are transistors,
40a is a primary coil of the pulse transformer 40. In addition, capacitor 10 is for noise absorption, capacitor 15 is for flame current detection, and resistor 30 is PUT34.
Resistor and capacitor 11 for passing the peak current of
3, 37, and 33 are for noise absorption.

In the ignition detection circuit D, 213, 21
5, 217, 219 are fixed resistors, 218 is a comparator, 216 is a noise absorption capacitor, 21
4 is a diode for discharging the capacitor 216. Note that the resistor 217 is a feedback resistor, and the resistor 217 is a feedback resistor.
9 is a pull-up resistor.

In the electromagnetic pump drive pulse width control circuit E, 42, 46, 47, 59, 66, 71, 72
are capacitors, 43, 44, 50, 51, 60,
52, 54, 65, 67, 55, 68, 73 are fixed resistors, 48 are variable resistors, 45, 69, 70 are transistors, 58 is PUT, 62 is a constant voltage diode, 61, 63, 64, 56 are diodes, 5
7 is an electromagnetic pump, 53 is a display for displaying pump drive, and 74 is a rectifier circuit consisting of a diode bridge. The capacitors 42 and 71 are for noise absorption, the variable resistor 48 is for pulse width adjustment, the capacitors 72 and 47 are for smoothing, the diode 61 is for temperature compensation, the diode 56 is for the flywheel of the pump 57, and the resistor 73 is for inrush current. For limitation, 40b is a secondary coil of the transformer 40.

In the above timing signal output circuit F, 26
0,289 is a set/reset flip-flop, 114,271,272,274,300 is an inverter, 259,281,283,275,
276, 278, 295, 269 are AND circuits formed with CMOS, 258, 261, 262, 2
87,288,273,293,294,29
9, 277, and 270 are OR circuits formed of CMOS; 290 is a decade counter that sequentially outputs an output to its output terminal every time a clock signal is input;
57,279,282,284,285,25
5,264,267,268,291,292,
296, 297, 301 are fixed resistors, 286, 2
98, 280 are capacitors, 265, 263 are diodes, 254 are transistors, 266 are light emitting diodes as an alarm device, 256 are relays 3
There are 63 contacts. In addition, resistor 296 and capacitor 298, resistor 279 and capacitor 280, resistor 2
85 and capacitor 286 are for time constant setting, and resistors 257, 282, 284, and 297 are for setting the time constant.
It is for CMOS protection.

In the above sequence timer G, 311 is an inverter, 310 and 320 are transistors, and 11
5 is short circuit pin for time saving, 317 is PUT, 31
4,319 is a capacitor, 308,309,31
2, 313, 315, 316, 318, and 321 are fixed resistances.

In the reset circuit H, 305, 306
is a fixed resistor, 307 is a diode, and 304 is a capacitor.
2,303 is a bypass capacitor.

In the anti-corrosion/water detection circuit I, 324 is a step-down transformer, 325 and 326 are diodes, 3
27, 333, 334, 335 are capacitors, 3
28,330,336,338,339,341
340 is a fixed resistor, 340 is a variable resistor, 331 is a comparator, 329 is a light emitting diode, 332 is a constant voltage IC, 337 is a constant voltage diode, 116 is an anti-corrosion electrode, and 117 is a can earth.

In the power supply circuit of the rectifier circuit 74, 342 is a household 100V commercial AC power supply, 343 is a current fuse, 351 is an ignition switch for turning the main power ON/OFF, and 345 is an indicator lamp indicating that the power outlet is energized. 350 is a combustion blower 348
349 is a contact point of relay 238, 118 is a surge absorption element, and resistor 3
57 and capacitor 358 are for noise absorption, 354
355 is an earthquake-resistant automatic fire extinguishing system, 355 is an oil sensor that detects the presence or absence of fuel, 356 is a relay contact that turns OFF when the decade counter 290 enters the fourth time, and 353 is an auto-cut temperature fuse that detects temperature connected in series. 363 is an earthquake-resistant automatic fire extinguishing device 354, an oil sensor 355, a relay contact 356, and an overheat preventer 3.
Reed switch that operates when 53 is normal, 3
Similarly to the reed switch 363, 60 is a neon lamp as a warning device that lights up when the above four things are normal to indicate normal operation and turns off when there is an abnormality, and 352 is for combustion regardless of the contact point 350. 366 is a vaporization heater, 365 is a temperature adjustment contact for vaporization heater 366, 367 is a thermostat for regulating the temperature of hot water inside the can, 368 is an ignition transformer, and 369 is an ignition transformer 368 only when igniting. It is a contact point for operating.

In the power supply circuits such as the ignition detection circuit D and the vaporization heater temperature control circuit B, 220, 22
1,251 is a bypass capacitor, 244 is a smoothing capacitor, 250 is a smoothing capacitor for negative power supply, 224, 229, 235, 241 is a resistor,
226, 231, 237, 240, 242 are transistors, 227, 232, 234, 238, 2
43 is a relay, 223, 228, 233, 23
9, 245, 246 are diodes, 249 is a negative power supply diode, 249 is a negative power supply diode, 252 is a constant voltage diode, 222
is a constant voltage IC, and 248 is a transformer.

In the boiling detection circuit J, 381, 38
2, 384, 387, 389, 391 are fixed resistors, 385 is a variable resistor for setting the water temperature detection level,
383 is a thermistor as a sensor for preventing abnormal overheating, 386 and 388 are capacitors, and 390 is a comparator. Note that the resistor 389 is for feedback, and the resistor 391 is for pull-up. Then, when abnormal overheating is detected by the thermistor 383, an output from the comparator 390 is inputted to the timing signal output circuit F due to a change in the resistance value, and a combustion stop operation is started. This signal is self-held in the flip-flop 260 and is configured not to be burned until it is reset. Moreover, at this time, the neon lamp 360 goes out and the light emitting diode 2
66 lights up to indicate an abnormality.

In the hot water temperature detection circuit K, 370, 37
1,373, 375, 378, 380 are fixed resistors, 374 is a variable resistor, 372 is a thermistor as a hot water temperature detection element, 376, 377 is a capacitor, 379 is a comparator, and the operation is the same as boiling detection circuit J. Heat exchanger 396 described below
When the temperature of the inflowing hot water reaches a predetermined value, a signal is output from the sequence circuit to cause the combustion device in a normal state to stop combustion.

Moreover, FIG. 2 is a schematic configuration diagram of a water heater having the above-mentioned control circuit. In the figure, 392 is the hot water supply port, 3
93 is a water supply port, 394 is a hot water storage tank, 395 is a first circulation pipe, 396 is a heat exchanger, 397 is a second
It is a circulation pipe, and the first and second circulation pipes 39
5,397, heat exchanger 396, hot water storage tank 394
A circulation route X is constructed. A thermovalve 398 is installed in the second circulation pipe 397 on the downstream side of the heat exchanger 396, and operates so that when the temperature of the hot water increases, the opening area increases, and when the temperature of the hot water decreases, the opening area narrows. 399 is a liquid fuel combustion device, 40
0 is the exhaust port.

The hot water temperature regulating thermostat 367 and the hot water temperature detecting thermistor 372 described above are arranged on the side wall of the hot water storage tank 394, and a heat exchanger 396 is also installed between the heat exchanger 396 and the thermovalve 398. Thermistor 3 is installed near the outlet to prevent abnormal overheating.
83 are provided.

To explain the operation of a water heater having a control circuit having such a configuration, when the power switch 351 is turned on, the combustion device 399 starts combustion under sequence control. This combustion heats the water in the heat exchanger 396 to reduce its specific gravity, and the hot water is stored in the upper part of the hot water storage tank 394 through the second circulation pipe 397. On the other hand, the water at the bottom of the hot water storage tank 394 is transferred to the first circulation pipe 39.
5 and enters the heat exchanger 396 and is heated.
In this way, the hot water storage tank 3
Hot water at a predetermined temperature is stored in the chamber 94. The thermovalve 398 is controlled so that the opening area increases as the water temperature increases and decreases as the water temperature decreases, so that hot water at a substantially constant temperature can be supplied to the upper part of the hot water storage tank 394.

Hot water is stored from the top of the tank 394, and when it passes the hot water temperature regulating thermostat 367, the thermostat 367 is turned off, but the hot water temperature detecting thermistor 372 causes the hot water temperature at the inlet of the heat exchanger 396 to exceed a predetermined value. Until this is detected, the relay contact 349 continues to energize the vaporization heater 366 and continue combustion.

As described above, since the natural circulation force is utilized, the amount of circulation decreases, and the amount of combustion may become larger than the amount of heat exchange, increasing the temperature of the hot water flowing into the heat exchanger 396. When this temperature is detected by hot water temperature detection thermistor 372 and exceeds a predetermined value, relay contact 349 is turned OFF by the output of comparator 379, fuel supply by electromagnetic pump 57 is stopped, and combustion in combustion device 399 is stopped. Thereafter, when the hot water temperature in the hot water storage tank 394 decreases due to hot water supply from the hot water supply port 392, it is detected by the hot water temperature regulating thermostat 367, and the combustion device 399 starts combustion.

In the combustion device control circuit of this hot water heater, if combustion does not stop due to a failure of the thermistor 372 mentioned above and heating continues in the heat exchanger 396, the area near the outlet of the heat exchanger 396 A thermistor 383 is provided to prevent abnormal overheating, and this thermistor 383 detects abnormal overheating of the hot water flowing out from the heat exchanger 396, and this detection signal is input to the timing signal output circuit by the comparator 390 to stop combustion. At the same time, the indicator lamp 3
The power supply to 60 is cut off and the light goes out, and the relay 363 is demagnetized and its contact 256 is opened, the transistor 254 is turned on, and the light emitting diode 266 is turned on to indicate an abnormality. This allows the heat exchanger 396
Abnormal overheating such as boiling inside can be quickly detected,
The life of the heat exchanger 396 can be significantly extended. Note that the abnormal overheating prevention signal by the thermistor 383 is reset by turning the switch 351 ON and OFF.

As described above, according to the present invention, a thermistor is provided near the outlet side of the heat exchanger to detect abnormally overheated water temperature, and an alarm device is provided to notify when an abnormality is detected by the thermistor. Compared to the conventional method, the reliability of detecting abnormal overheating is significantly improved, and abnormal conditions can be quickly notified, and the life of heat exchangers and the like can be significantly extended.

In addition, the heating capacity can be increased by increasing the combustor capacity, and a natural circulation water heater that is safe and has excellent boiling performance can be provided.

[Brief explanation of the drawing]

FIG. 1 is an overall circuit diagram showing one embodiment of a combustion device control circuit for a water heater according to the present invention, and FIG. 2 is a schematic configuration diagram of the same water heater. 266...Light emitting diode, 360...Neon lamp, 372...Thermistor for water temperature detection, 38
3... Thermistor for preventing abnormal overheating, 394... Hot water storage tank, 395... First circulation pipe, 396...
...Heat exchanger, 397...Second circulation pipe, 399
...Combustion device.

Claims (1)

[Scope of Claims] 1 A circulation pipe is connected to a hot water storage tank, and hot water heated by a heat exchanger installed in the pipe is circulated and supplied to the upper part of the hot water storage tank for storage, while the hot water is stored in the hot water storage tank. In a water heater equipped with a hot water temperature detection element that detects the temperature of incoming water and outputs a signal to stop combustion of a liquid fuel combustion device, which is a heating source of a heat exchanger, when the temperature reaches a predetermined value, the heat exchanger of the circulation pipe The sensor has an abnormal overheating prevention sensor installed on the downstream side of the heat exchanger, which detects the temperature of the hot water flowing into the heat exchanger and outputs a combustion stop signal when the temperature reaches a predetermined value, regardless of the output of the hot water temperature detection element. 1. A combustion device control circuit for a water heater, comprising: an abnormality alarm device that is activated when the signal is output from the combustor. 2. The abnormality alarm device is a neon lamp for indicating normal operation of the combustion device and a light emitting diode for indicating abnormality, and when the abnormal overheating prevention sensor outputs a combustion stop signal, the neon lamp turns off and the light emitting diode turns on. A combustion device control circuit for a water heater according to claim 1, which is configured to perform the following.