JPH0730911B2 - Water heater control device - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for a gas instantaneous water heater used in a kitchen or the like.

2. Description of the Related Art In recent years, safety has been emphasized in small gas instantaneous water heaters by incorporating a device for preventing incomplete combustion during oxygen deficiency and fin clogging of a heat exchanger.

An example of the conventional small-sized gas instantaneous water heater described above will be described below with reference to the drawings.

FIG. 3 shows an overall configuration diagram of a conventional small-sized gas instantaneous water heater.

In FIG. 3, 1 is a water stopcock arranged in the water supply channel, 2 is a water governor, and 3 is a heat exchanger. Reference numeral 4 is a solenoid valve provided in the gas supply passage, 5 is a gas governor, and 6 is a hydraulically responsive gas valve that responds to the pressure of water flowing through the water supply passage. 7 is an ignition device, 8 is a main burner, 9 is a pilot burner, 10
Is a main thermocouple for detecting ignition of the pilot burner 9, 11 is a reverse thermocouple for detecting fin clogging of the heat exchanger 3, and the main thermocouple 10
Is connected so that a back electromotive force is applied. Reference numeral 12 is a control circuit for controlling the entire device.

The operation of the small gas instant water heater configured as described above will be described below.

First, when the ignition button is pressed, the solenoid valve 4 is opened, gas flows to the pilot burner 9, and the ignition device 7 ignites. When the pilot burner 9 is ignited, the main thermocouple 10 for detecting the pilot burner ignition is heated and an electromotive force is generated. The solenoid valve 4 is forcibly kept open by the control circuit 12 for a certain period after ignition operation (hereinafter referred to as forced adsorption time). At the same time, the water stopcock 1 is opened, the water governor 2 adjusts the water volume to a constant amount, and the water flows into the heat exchanger 3. The hydraulically actuated gas valve 6 is opened by this flow of water, and the gas whose gas amount has been adjusted to a constant amount by the gas governor 5 flows to the main burner 8 and is ignited by the pilot burner 9 to burn. The heat exchanger 3 is heated by this combustion gas to warm the water and obtain hot water.

Here, the electromotive force generated from the main thermocouple 10 and the inverse thermocouple 11 and the operation of the solenoid valve 4 will be described with reference to the drawings. FIG. 4 is a diagram showing the relationship between the generation of each electromotive force of the main thermocouple 10 and the reverse thermocouple 11 at the time of ignition and the time (note that the electromotive force of the reverse thermocouple 11 is shown as a positive value by reversing a negative value). The same applies to the following figures). Figure 5 shows oxygen concentration and main thermocouple 1
FIG. 3 is a diagram showing 0 / each electromotive force of the reverse thermocouple 11 and CO / CO ₂ . Fig. 6 shows the fin blocking rate of the heat exchanger 3 and the main thermocouple 1
FIG. 3 is a diagram showing each electromotive force of 0 and the inverse thermocouple 11 and CO / CO ₂ .
As shown in FIG. 4, after the ignition operation of the main burner 8, the electromotive force of each of the main thermocouple 10 heated by the pilot burner 9 and the reverse thermocouple 11 heated by the combustion gas of the main burner 8 increased with time. To go. Here, if the composite electromotive force (the sum of the electromotive forces of the main thermocouple 10 and the reverse thermocouple 11) is higher than the cutoff voltage of the solenoid valve 4 after the forced adsorption, the solenoid valve 4 is kept open by the composite electromotive force. Flapping combustion continues. When the composite electromotive force is lower than the cutoff voltage of the solenoid valve 4, the solenoid valve 4 is cut off and the gas supply is stopped. Therefore, if the gas instantaneous water heater is used for a long time and the oxygen concentration in the air in the room in which the gas instantaneous water heater is installed decreases as shown in FIG. 5, combustion of the pilot burner 9 becomes unstable and the main thermocouple
The electromotive force of 10 is reduced, and the composite electromotive force is reduced. When this composite electromotive force falls below the cutoff voltage of the solenoid valve 4, the solenoid valve 4 is shut off and the gas supply is stopped to prevent an oxygen deficiency accident.

Further, as shown in FIG. 6, if the fin blocking rate of the heat exchanger 3 increases due to some accident, the electromotive force of the inverse thermocouple 11 increases, and as a result, the composite electromotive force decreases. When the combined electromotive force falls below the cutoff voltage of the solenoid valve 4, the solenoid valve 4 is cut off, the gas supply is stopped, and the incomplete combustion of the main burner 8 is prevented. FIG. 7 is a diagram showing the fin blocking rate of the heat exchanger 3, the electromotive force of each of the main thermocouple 10 and the inverse thermocouple 11, and CO / CO ₂ when the gas combustion amount is reduced.

Problems to be Solved by the Invention However, in the above-described configuration, as shown in FIG. 7, when the gas combustion amount is small, even if the fin blockage rate of the heat exchanger 3 becomes high, the heat is generated from the reverse thermocouple 11. The resulting electromotive force is slow to increase, and as a result, the composite electromotive force is slow to decrease. Therefore, the blocking rate when shutting off the solenoid valve 4 becomes high, and the CO
The value of / CO ₂ becomes large and it becomes unsafe. Therefore, if the cutoff voltage of the solenoid valve 4 is increased, it will be on the safe side at the time of oxygen deficiency and fin closing, but if the combined electromotive force after the initial ignition forced adsorption is lower than the cutoff voltage of the solenoid valve 4,
There was a problem that the equipment could not be used because it was cut off. Further, if the forced adsorption time is extended, a large amount of the forced adsorption current is required for that time, and the dry battery serving as the power source of the solenoid valve 4 is quickly consumed. Further, if the forced adsorption time is extended, if the ignition spark does not fly, raw gas will be emitted for a long time, which is a safety problem.

In view of the above problem, the present invention provides a safer solenoid valve 4 while the CO / CO ₂ value when fins are closed is low, regardless of the gas combustion amount.
The present invention provides a safer and more convenient gas instantaneous water heater by shutting off the gas and stopping the supply of gas and eliminating the fire extinguishing due to insufficient electromotive force of the thermocouple in the initial stage of ignition.

Means for Solving the Problems In order to solve the above problems, a gas instantaneous water heater of the present invention is a main thermocouple that generates an electromotive force heated by a pilot burner and a main thermocouple attached to a heat exchanger. And a reverse thermocouple for detecting fin blockage that generates an electromotive force of the opposite polarity, a solenoid valve provided in a part of the gas passage for controlling the fuel supply of the main burner and pilot burner, the main thermocouple and the reverse thermocouple. The combined electromotive force generated from the pair is below a certain level defined in accordance with the allowable incomplete combustion standard, or the electromotive force generated from the reverse thermocouple corresponds to the allowable fin clogging degree of the heat exchanger. When it exceeds a certain level defined by
And a pilot safety circuit configured to close the solenoid valve.

Action The present invention has the above-described configuration to shut off the solenoid valve when the reverse polarity electromotive force generated from the reverse thermocouple exceeds a certain level, so that heat exchange is performed even when the gas combustion amount is small. The solenoid valve can be shut off even when the obstruction rate of the vessel is low and the CO / CO ₂ value is low, thus improving safety.

Embodiment A gas instantaneous water heater according to an embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is an overall configuration diagram of a gas instantaneous water heater according to an embodiment of the present invention. The same parts as those of the prior art are designated by the same reference numerals, detailed description thereof will be omitted, and different parts will be mainly described. 13 is a main thermocouple that generates electromotive force heated by the pilot burner 9, 14 is a heat exchanger 3 that is attached to the heat exchanger 3, and a reverse thermocouple for detecting fin clogging that generates an electromotive force having a polarity opposite to that of the main thermocouple 13; Reference numeral 15 is a solenoid valve, and 16 is a pilot safety circuit connected to the series circuit of the main thermocouple 13 and the inverse thermocouple 14 and connected to the solenoid valve 15. FIG. 2 shows an embodiment of the pilot safety circuit. When the composite electromotive force, which is the sum of electromotive forces generated by the main thermocouple 13 and the inverse thermocouple 14 in the first operational amplifier 17, falls below a certain level, the _Lo signal is output. Out the second operational amplifier
At 18, when the electromotive force generated from the inverse thermocouple 14 exceeds a certain level, the _Lo signal is output. 19 is an AND logic element, the first operational amplifier 17 is _Lo or the second operational amplifier 18 is _Lo , or
When the operational amplifier 17 and the second operational amplifier 18 are both _Lo , it outputs the _Lo signal. To shut off the solenoid valve 15 by the L _o signal. That is, in addition to the determination of the sum of electromotive forces of the main thermocouple 13 and the inverse thermocouple 14, the main burner 8 due to the soot clogging of the fins and the like as compared with the conventional case.
Incomplete combustion occurs and the rise in electromotive force of the inverse thermocouple 14 is slow due to the small amount of gas combustion. At the end of the forced adsorption time of the valve 4, the circuit that shuts off the solenoid valve 15 when the level exceeds a certain level higher than the electromotive force when the fin clogging degree is small is added, providing a safer gas instantaneous water heater. it can.

As described above, according to the present invention, the fins of the heat exchanger are clogged to the allowable level, and when the gas combustion amount exceeds a certain level set under the combustion condition, the electromagnetic valve is generated by the reverse polarity electromotive force generated from the reverse thermocouple. Since the gas is cut off, it is possible to reduce the amount of incomplete combustion gas that is dangerous to the human body and improve the safety of use.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram of a gas instantaneous water heater in an embodiment of the present invention, FIG. 2 is a pilot safety circuit diagram thereof, FIG. 3 is an overall configuration diagram of a conventional gas instantaneous water heater, and FIG. The conventional electromotive force characteristic diagram, FIG. 5 is the electromotive force characteristic diagram when the same oxygen deficiency, 6
FIG. 7 is a characteristic diagram of electromotive force when fins are closed at the same gas combustion amount, and FIG. 7 is a characteristic diagram of electromotive force when fins are closed at the same gas combustion amount. 13 …… Main thermocouple, 14 …… Inverse thermocouple, 15 …… Solenoid valve, 16…
… Pilot safety circuit.

Claims (1)

[Claims] 1. A pilot burner, a main thermocouple which is heated by the pilot burner to generate an electromotive force, a main burner, a heat exchanger which is heated by the main burner, and between the heat exchanger and the main burner. A reverse thermocouple for detecting fin blockage that is heated by the combustion gas and that generates an electromotive force of the opposite polarity to the main thermocouple, and a part of the gas passage that controls the fuel supply to the main burner and pilot burner. The composite electromotive force generated from the solenoid valve, the main thermocouple and the reverse thermocouple becomes equal to or lower than a certain level determined corresponding to the allowable incomplete combustion standard, or the reverse polarity generated from the reverse thermocouple. Control device for a water heater comprising: a pilot safety circuit configured to close the solenoid valve when the electromotive force of the above-mentioned becomes equal to or higher than another fixed level determined corresponding to the allowable fin clogging degree of the heat exchanger.