JPS6136136B2 - - 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 at the bottom of the hot water storage tank or low-temperature water is heated via a heat exchanger and circulated as high-temperature hot water to the top of the hot water storage tank, and hot water at a constant temperature is gradually stored from the top of the tank. . This is due to the natural circulation force generated by the head pressure difference and temperature difference between the inlet and outlet of the heat exchanger.

Further, the circulation pipe on the downstream side of the heat exchanger is equipped with a thermovalve whose opening area increases or decreases depending on the high-temperature hot water passing through it, and when the hot water temperature rises, the opening area increases and the flow rate increases, and when the water temperature becomes low, the By reducing the area and reducing the flow rate, hot water at a substantially constant temperature is supplied to the upper part of the tank.
For this reason, when the amount of hot water in the tank decreases during hot water supply and the combustion device starts heating, high-temperature hot water is supplied to the top of the tank, so the actual amount of hot water stored is significantly larger than that of conventional hot water storage, and it can be stored without expanding the space. You can increase the amount.

However, in conventional hot water storage type water heaters, the hot water temperature is controlled by turning the combustion device on and off using a thermostat.
It was done as follows. In the case of this thermostat, the response speed is slow, and if the heating capacity of the combustion device is increased, it will have a negative effect on the heat exchanger, etc., so the heating capacity must be kept small, which results in a longer boiling time. There were flaws. In addition, since the combustion device is constantly controlled on and off even when hot water is not being supplied, the combustion device is used frequently and is prone to failure, which has a negative impact on its lifespan.

The present invention was made in view of the above circumstances, and
A first hot water temperature sensing element that turns on the combustion device, and a second hot water temperature sensing element with a fast response speed that turns off the device.
An object of the present invention is to provide a combustion device control circuit for a water heater that eliminates the conventional drawbacks by providing a hot water temperature detection element.

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, sequence timer G
and a 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 resistors 7 and 8 are a pull-up resistor and a feedback resistor, respectively, 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. The diodes 90 and 92 are for input protection of the operation amplifier 95, the resistor 96 and capacitors 94 and 97 are for preventing oscillation of the operation amplifier 95, the capacitors 76 and 103 are for noise absorption, and the diode 2
05, 206 and resistors 109, 204 are used to prevent latch-up due to a negative voltage being applied to the input of the comparator 208 and the comparator 6 in the evaporative heater protection circuit A, and the capacitor 203
is for preventing chattering, resistor 210 is for pull-up, and resistors 93, 107, and 204 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, 304
is PUT, 111 is burner section, 247 is flame current detection electrode, 10, 15, 20, 32, 33, 37 is capacitor, 27, 38, 39 is transistor,
40a is a primary coil of the pulse transformer 40. In addition, capacitors 10, 33, 37, and 113 are for noise absorption, capacitor 15 is for flame current detection,
The resistor 30 is a resistor for allowing the peak current of the PUT 34 to flow.

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 resistors 217 and 219 are for feedback and pull-up, respectively.

In the electromagnetic pump drive pulse width control circuit E, 42, 46, 47, 59, 66, 71, 72
are capacitors, 43, 44, 50, 51, 52,
54, 55, 60, 65, 67, 68, 73 are fixed resistors, 48 are variable resistors, 45, 69, 70 are transistors, 58 is PUT, 62 is a constant voltage diode, 56, 61, 63, 64 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 capacitors 47 and 72 are for smoothing, the variable resistor 48 is for pulse width adjustment, the diodes 61 and 56 are for temperature compensation and the flywheel of the pump 57, respectively, and the resistor 73 is for inrush current. For limitation, 40b is a secondary coil of the pulse 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 each 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 and 280 are capacitors, 265 and 263 are diodes, 254 is a transistor, 266 is a light emitting diode, and 256 is a contact point of the relou 363. In addition, resistor 296, capacitor 298, resistor 2
79 and capacitor 280, resistor 285 and capacitor 286 are for time constant setting, resistor 257,
282, 284, and 297 are for CMOS protection.

In the above sequence timer G, 311 is an inverter, 310 and 320 are transistors, and 11
5 is a short circuit pin for time saving, 317 is RUT, 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. Further, 302 and 303 in the power supply circuit of the reset circuit H are bypass capacitors.

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 neo lamp that lights up when the above four items are normal to indicate normal operation; 352 is a contact point 350;
366 is a vaporization heater, 365 is a temperature adjustment contact for the vaporization heater 366, and 367 is a water temperature as a first water temperature detection element that detects the water temperature inside the can. Adjustment thermostat, 368 is ignition transformer,
369 is a contact point for operating the ignition transformer 368 only during ignition.

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 fixed resistor, 226, 231, 237, 240, 242 is a transistor, 227, 232, 234, 23
8,243 is a relay, 223,228,233,
239, 245, and 246 are diodes, 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 resistors 389 and 391 are for feedback and pull-up, respectively. When abnormal overheating is detected by the thermistor 383, the change in resistance causes the comparator 390 to
The output is then input to the timing signal output circuit F, and combustion stop operation begins. This signal is self-held in flip-flop 260 and is configured not to burn until it is reset. Moreover, at this time, the neon lamp 360 goes out and the light emitting diode 26
6 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 second water temperature detection element, 376, 377 are capacitors, 379 is a comparator, and the operation is the same as boiling detection circuit J. However, it outputs a signal to cause the sequence circuit to output a signal to stop combustion in the combustion device when it is operating under normal conditions.

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. 398 is a thermovalve installed in the second circulation pipe 397 on the downstream side of the heat exchanger 396. When the water temperature rises, the opening area expands and the flow rate increases, and when the water temperature falls, the area narrows and the flow rate increases. It works to decrease. 3
99 is a liquid fuel combustion device, and 400 is an exhaust port.

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

To explain the operation of a water heater having such an abnormal control circuit, 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 and its specific gravity becomes lighter, which causes the second circulation pipe 397 to
The hot water rises and is supplied to the upper part of the hot water storage tank 394. On the other hand, the water at the bottom of the hot water storage tank 394 is transferred to the first circulation pipe 3.
It flows into the heat exchanger 396 via 95 and is heated. In this way, hot water at a predetermined temperature is stored in the hot water storage tank 394 by utilizing the natural circulation force due to the water head pressure and temperature difference between the inlet and outlet of the heat exchanger 396. The thermovalve 398 increases its opening area when the hot water temperature becomes high, and decreases when the hot water temperature decreases to adjust the flow rate so that hot water at a substantially constant temperature can be supplied to the upper part of the hot water storage tank 394 under a constant combustion amount. It's in control.

During the above-mentioned hot water storage, the water temperature is measured by the thermistor 37.
When the set value of the thermostat 367, which is lower than the set value of 2, is reached, the thermostat 367 is turned off, but the output of the comparator 379 makes the transistor 240 conductive, and the relay 238 remains energized and its contact 349 remains closed. Energization to vaporization heater 366 and combustion continue. Thereafter, when the water temperature rises and reaches the set value of the thermistor 372, the output of the comparator 379 turns off the transistor 240, demagnetizes the relay 238, and opens the relay contact 349, causing the vaporization heater 36
6 is cut off, combustion operation is also stopped, and hot water is stored. Since the hot water temperature at this time is considerably higher than the set value of the thermostat 367, repeated combustion is unlikely to occur during hot water storage. Furthermore, since the combustion stop signal is output by the thermistor 372, its response speed is faster than in the past and combustion can be stopped instantaneously, making it possible to prevent damage to the heat exchanger 396 even when a combustion device with a large heating capacity is used. ,
Moreover, the heating time is shortened.

On the other hand, during hot water supply, water is supplied from the water supply port 393 into the hot water storage tank 394 as hot water is supplied from the hot water supply port 392 . The inflowing water reaches the thermostat 36
When it reaches position 7, thermostat 367 turns on.
Then, energization to the vaporization heater 366 is started, and the combustion operation is also started by a signal from the sequence circuit, and hot water is supplied to the upper part of the hot water storage tank 394.
In this case, since the heating capacity of the combustion device is large, the supply of hot water will not be interrupted.

For safety, a thermistor 383 for preventing abnormal overheating is provided downstream of the heat exchanger 396 to monitor the temperature of hot water flowing out from the heat exchanger 396, and when the temperature exceeds a predetermined temperature, a timing signal input circuit is sent from the comparator 390. A signal is output to stop combustion and prevent boiling within the heat exchanger 396. When the signal is output, the neon lamp 360 is turned off and the light emitting diode 2 for abnormality indication is turned off.
66 lights up to indicate an abnormality. In place of the thermistor 372, a positor, thermocouple, etc. may be used.

As described above, according to the present invention, the combustion device
Since ON and OFF are controlled using separate temperature detection elements, and a thermistor with a fast response speed is used for the OFF signal, a combustion device with large heating capacity can be used, heating time can be shortened, and the control circuit It is also possible to shorten the energization time. In addition, the combustion device is used less frequently, and the life of the water heater can be significantly extended.

[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. 367... Thermostat (first hot water temperature detection element), 372... Thermistor (second hot water temperature detection element), 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 the 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 through the pipe to store hot water, and the hot water inside the hot water storage tank is In a water heater that detects the water temperature with a water temperature detection element and controls ON/OFF of the liquid fuel combustion device that is the heat source of the heat exchanger, when the water temperature in the hot water storage tank is detected and falls below the set value. a first hot water temperature sensing element that outputs an ON signal for the combustion device; and a first hot water temperature sensing element that detects the hot water temperature in the hot water storage tank and has a faster hot water temperature detection response speed than the first hot water temperature sensing element. A combustion device control circuit for a water heater, characterized in that a second hot water temperature detection element outputs an OFF signal for the combustion device when the temperature reaches a high set value. 2. The combustion device control circuit for a water heater according to claim 1, wherein the second hot water temperature sensing element is a thermistor.