JPH0235209B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a combustion control circuit for a combustor equipped with an electromagnetic safety valve.

(Prior art) An electromagnetic safety valve interposed in the gas supply path is opened manually, and the safety valve is opened by the discharge current flowing through the discharge circuit of the capacitor and the electromotive force that reaches a predetermined value from the thermocouple facing the sub-burner. In the combustion control circuit that maintains the valve in an open state, the safety valve is forcibly opened by the discharge current, so if the auxiliary burner is not ignited due to an ignition error, the main gas passage connected to the main burner is opened. However, there is a disadvantage that a large amount of raw gas is released from the main burner for a relatively long period of time.

In order to solve this problem, for example, as disclosed in Japanese Utility Model Application No. 57-105529,
It has been proposed to interpose a normally closed switch in the discharge circuit of the capacitor, which opens in conjunction with the opening of the main gas passage connected to the main burner, thereby cutting off the discharge current and closing the safety valve.

(Problems to be Solved by the Invention) This proposed circuit uses the normally closed switch in the discharge circuit of the capacitor, so that, for example, when water is turned on relatively quickly after ignition of the sub-burner, Second, if the normally closed switch is opened before the capacitor has finished discharging, a charge remains in the capacitor. Since this charge can only be dissipated by natural discharge, it takes a long time for the charge to disappear completely. Therefore, even if the solenoid of the safety valve is inserted into the capacitor's charging circuit again during a fire extinguishing operation and a charging current of opposite polarity is applied to the thermoelectromotive current caused by the residual heat of the thermocouple, a charge remains in the capacitor. A sufficiently large charging current does not flow. Therefore, the thermoelectromotive current due to the residual heat of the thermocouple heated by the ignition of the auxiliary burner overcomes the charging current, so the safety valve is not closed immediately, but when the electromotive force of the thermocouple falls to a predetermined value due to natural cooling. Close the valve. Therefore, immediately after pressing the fire extinguishing button, the safety valve is held in the open state, and at this point, when the ignition push button is pressed, especially when the amount of pressure is small, the shutoff valve opens, but the igniter does not operate. This results in gas leaking from the auxiliary burner, and furthermore, raw gas is released from the main burner when, for example, a faucet is opened. An object of the present invention is to provide a combustion control circuit free from such disadvantages.

(Means for Solving the Problems) The present invention provides gas passages for the main burner and the sub burner.
Interposes an electromagnetic safety valve that is manually pressed open,
A changeover switch is provided that is linked to the press opening of the safety valve, and the changeover switch switches the solenoid of the safety valve from intervention in the capacitor charging circuit to intervention in the capacitor discharge circuit, and changes the discharge current of the capacitor to a predetermined value. The safety valve is held open by the electromotive force of the thermocouple facing the sub-burner, and the discharge circuit of the capacitor is opened in conjunction with the opening of the main gas passage connected to the main burner. In cases where a normally closed switch is used,
It is characterized in that a resistor is connected in parallel with the normally closed switch.

(Example) An example of the present invention will be described with reference to a water heater shown in the drawings.

In FIG. 1, 1 is a main burner, 2 is a sub-burner, and 3 is a gas passage that supplies fuel gas to the main burner 1. The gas passage 3 includes an electromagnetic safety valve 4, a cutoff valve 5, and a hydraulic response member 6. The cutoff valve 5 and the electromagnetic safety valve 4 are interposed with an automatic valve 7 that responds to the
is pressed open by the manual operation member 8. To explain this in detail, the operation member 8 is composed of an ignition push button 8a that passes through the operation panel 9 on the front side of the water heater, and an operation rod 10 that is inserted into the gas passage 3 on the front side of the ignition push button 8a. , when the operating rod 10 is provided with the shutoff valve 5, and the push button 8a is pressed against the return spring 8b from the starting end position, the shutoff valve 5 is pressed open at the intermediate position of the pressing operation. At the end position, the electromagnetic safety valve 4 is pressed open via the lever 12. The auxiliary burner 2 is composed of a pilot burner 2b and a constant flame burner 2a, and fuel gas is supplied to the constant flame burner 2a through a gas passage 11 located between the cutoff valve 5 and the automatic valve 7. , the pilot burner 2b is connected to the gas passage 3 via an ignition valve 13 formed between the side wall of the gas passage 3 and a narrow diameter portion 10a provided on the operating rod 10.
A gas passage 1 connected between a shutoff valve 5 and an automatic valve 7
Fuel gas was supplied through 4. The ignition valve 13 is configured to open when the ignition push button 8a is pressed to the final position. Reference numeral 15 indicates a thermocouple facing the auxiliary burner 2, and 16 indicates an igniter also facing the auxiliary burner 2. The igniter 16 is activated by a switch 16a that closes at a pressed position past the intermediate position of the push button 8a. do.

The present invention relates to a circuit for controlling the safety valve 4 interposed in the gas supply path 3 of the combustor, and FIG. 2 shows an embodiment of the circuit. In the circuit shown in the same figure, the solenoid 4 of the electromagnetic safety valve 4
a indicates a movable contact 18c and a fixed contact 18 of the changeover switch 18, which are closed when the capacitor 17 is extinguished.
capacitor 17 connected to power supply 19 via a
is inserted into the charging circuit 20 of the capacitor 1.
7 is inserted into a discharge circuit 21 which is discharged through the movable contact 18c and the fixed contact 18b of the changeover switch 18, which are closed when the push button 8a is pressed. A normally closed switch 22 that is opened in conjunction with the valve opening operation of 7.
is intervened, and a resistor 2 is connected in parallel with the normally closed switch 22.
3 are connected.

When the operating member 8 is pressed by the ignition push button 8a, the switch 18 is first switched to the side that closes the discharge circuit 21, and then the shutoff valve 5 opens at the intermediate position and the electromagnetic safety valve 4 is pushed at the terminal position. At the same time as opening, the ignition switch 16a is closed. Therefore, the electric charge stored in the capacitor 17 begins to be discharged via the normally closed switch 22 which intervenes in the discharge circuit 21, and the solenoid 4a is excited by this discharged electric charge and holds the electromagnetic safety valve 4 open.

Therefore, even if the push button 8a is released, the electromagnetic safety valve 4 remains open. During this operation, the operating member 8 is locked by the locking device 30 at an intermediate position that keeps the shutoff valve 5 open when the pressing operation is released.

The charge in the capacitor 17 decreases over time and reaches the detachment current value after a predetermined period of time has elapsed, but when combustion is normally occurring in the secondary burner 2, an electromotive force is generated in the thermocouple 15. The electromagnetic safety valve 4 continues to be held open.

However, if the water faucet is opened at the same time as the ignition operation when the sub-burner 2 is not lit, or a little later than this, the intermediate position 22 is opened in conjunction with the opening of the automatic valve 7, so the electric charge in the capacitor 17 is The discharge circuit 2
1, the voltage is discharged through the resistor 23 intervening in the voltage 1. As a result, the discharge current value of the capacitor 17 rapidly decreases, thereby quickly reaching the withdrawal current value that closes the electromagnetic safety valve 4. Therefore, when the sub-burner 2 is not ignited, the electromagnetic safety valve 4 closes immediately.
The release of raw gas can be suppressed as much as possible.

On the other hand, when the sub-burner 2 is ignited but the thermocouple 15 is not generating a predetermined electromotive force, when the faucet is opened and the gas passage 3 is opened, the discharge current is caused by the intervention of the resistor 23. Even if the value drops rapidly, the discharge will occur gradually, and the remaining current will
Since the current due to the electromotive force of the thermocouple 15 is added, it is possible to keep the current above the withdrawal current value, and once the auxiliary burner 2 is ignited, the electromagnetic safety valve 4 will not be closed.

To extinguish the fire, press the fire extinguishing push button 24, the locking device 30 will be unlocked, and the operating member 8 will release the spring 8.
b automatically returns, and this action closes the shutoff valve 5 to cut off the supply of fuel gas to both burners 1 and 2 to extinguish the fire, and the return action of the operating member 8 causes the changeover switch 18 to close the charging circuit 20. Then, a charging current of the opposite polarity flows through the solenoid 4a to cancel the thermal electromotive current due to the residual heat of the thermocouple 15, and the electromagnetic safety valve 4 immediately closes.

Next, for example, following the ignition of the auxiliary burner 2, water is supplied relatively quickly, the water is stopped after a predetermined period of time, the extinguishing push button 34 is pressed, and the extinguishing operation is performed. The operation when the ignition push button 8a is pressed, especially when the pressing operation is performed with a small amount of pressing, will be explained.

When the normally closed switch 22 is opened after the water flow operation, a charge remains in the capacitor 17, but this charge continues to be discharged through the resistor 23, so when the fire extinguishing push button 24 is pressed, the power is turned off. 19
A sufficiently large charging current flows into the charging circuit 20 from
Thermocouple 1 flowing into solenoid 4a due to residual heat
Since the thermal electromotive current of 5 is canceled out, the electromagnetic safety valve 4 immediately closes.

In this way, even when the ignition push button 8a is repeatedly pressed within a short period of time after the ignition push button 24 is pressed to an extent that does not close the ignition switch 16a, there is no leakage from the auxiliary burner 2, and even in that state. Raw gas is not released from the main burner 1 even when the water faucet is opened.

FIG. 3 shows an operational characteristic diagram of a specific circuit in such a case.

This characteristic is that in the circuit shown in FIG. 2, the capacitor 17 has a value of 3.3F and the resistor 23 has a value of 2.5Ω.
Furthermore, although not shown, this is the case when a 1.3Ω resistor is inserted into the charging/discharging circuit of the capacitor 17.
In Figure 3, A(-x-) is the solenoid 4a
The charging/discharging current of the capacitor 17 flowing to B(-o
-) is the thermoelectromotive current of the thermocouple 15 flowing to the solenoid 4a, C(-) is A and B flowing to the solenoid 4a
The resultant current is shown below the zero line. The current value indicates a polar current value flowing through the solenoid 4a from top to bottom in the figure.

According to FIG. 3, after ignition, water is supplied after 2 seconds when the capacitor 17 is not sufficiently discharged, water is stopped after a predetermined period of time, for example, 7 seconds, and then the fire is extinguished after a short period of time, for example, 1 second. The voltage applied to solenoid 4a is 1.074V, and the charging current flowing is 413mA. On the other hand, since the thermoelectromotive current of the thermocouple 15 due to residual heat at the time of extinguishing the fire is 400 mA, the combined current is 13 mA, which is less than the withdrawal current value that closes the electromagnetic safety valve 4. Therefore, the electromagnetic safety valve 4 closes almost simultaneously with the extinguishing operation.

FIG. 4 shows the circuit disclosed in the above-mentioned Japanese Utility Model Publication No. 57-105529, under the same conditions as the circuit shown in FIG.
The operating characteristics diagram when water is stopped and fire extinguished is shown. In the same figure, A', B', and C' are A', B', and C' in Figure 3.
They correspond to B and C, respectively. As is clear from this figure, according to the circuit in the publication, the combined current flowing through the solenoid of the electromagnetic safety valve at the time of extinguishing the fire is
110mA is more than the withdrawal current. Therefore, the electromagnetic safety valve 4 does not close at the same time as the fire extinguishing operation, but remains open until the thermocouple is naturally cooled.

Note that since the above-mentioned embodiment was applied to a water heater, the opening operation of the gas passage was performed by an automatic valve 7 that responds to water pressure. However, the circuit of the present invention can be applied to a bath control circuit, etc. In this case, the gas passage is opened and closed using a manual valve that is opened and closed manually.

(Effects of the Invention) According to the present invention, the solenoid of the safety valve is switched from intervening in the capacitor charging circuit to intervening in the capacitor discharging circuit by a changeover switch that is linked to manual opening of the electromagnetic safety valve. The safety valve is held in an open state by the discharge current of the discharge current and the electromotive force of the thermocouple, and a normally closed switch that opens in conjunction with the opening operation of the main gas passage connected to the main burner is inserted in the discharge circuit of the capacitor. In this case, a resistor is connected in parallel with the normally closed switch, so that the normally closed switch can be opened by opening the main gas passage at a relatively early stage, for example, after the auxiliary burner has ignited and before the capacitor has finished discharging. If the ignition button is opened, after a predetermined period of time has elapsed since the opening operation, the main gas passage must be closed and the fire extinguished, and the ignition push button must be pressed again before the electromotive force of the thermocouple falls to the predetermined value. Gas does not leak from the auxiliary burner even when the amount is small, and raw gas is not released from the main burner when the main gas passage is opened.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a water heater applied to the implementation of the present invention, FIG. 2 is a circuit diagram of an embodiment of the present invention, and FIG.
The figure shows its operating characteristic diagram, and FIG. 4 shows the operating characteristic diagram of the conventional circuit. 1...Main burner, 2...Sub burner, 3...Gas passage, 4...Solenoid safety valve, 4a...Solenoid of the electromagnetic safety valve, 15...Thermocouple, 16...Igniter,
17... Capacitor, 18... Selector switch, 1
9... Power source, 20... Charging circuit, 21... Discharging circuit, 22... Normally closed switch, 23... Resistor, 24
...Push button for extinguishing fire.

Claims (1)

[Claims] 1. An electromagnetic safety valve that is manually pressed and opened is interposed in the gas passages of the main burner and the auxiliary burner, and a changeover switch that is linked to the pressure opening of the safety valve is provided, and the changeover switch connects the solenoid of the safety valve to the capacitor charging circuit. The safety valve is maintained in an open state by the discharge current of the capacitor and the electromotive force of the thermocouple facing the sub-burner that has reached a predetermined value. and a normally closed switch that opens in conjunction with the opening operation of the main gas passage connected to the main burner is inserted in the discharge circuit of the capacitor, characterized in that a resistor is connected in parallel with the normally closed switch. combustion control circuit.