JPH0361091B2 - - 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) Conventionally, as shown in FIG. 7, a changeover switch a is provided which is linked to manual opening of an electromagnetic safety valve interposed in the gas passages of the main burner and the sub-burner. Solenoid b is connected to the charging circuit of capacitor c.
In this type of device, the safety valve is maintained in an open state using the discharge current of the capacitor c and the thermoelectromotive current reaching a predetermined value of the thermocouple facing the sub-burner. In the combustion control circuit shown in FIG. There is a known device that prevents a large amount of raw gas from being released from the main burner for a relatively long time when the main gas passage connected to the main burner is opened when ignition is not performed (for example, Utility Model No. 57-105529
Publication No.).

(Problems to be Solved by the Invention) In the above-mentioned conventional technology, following the ignition of the sub-burner by the ignition operation, the water flow operation is performed relatively quickly and the normally closed switch is opened before the discharge of the capacitor is completed. A charge remains in the capacitor. Therefore, it is sufficient to insert the solenoid of the electromagnetic safety valve into the charging circuit of the capacitor during extinguishing operation after such a relatively quick water flow operation, and to flow a charging current of the opposite polarity to the thermoelectromotive current caused by the residual heat of the thermocouple in the solenoid. Large charging current does not flow. Thus, the safety valve does not close immediately, but closes when the thermoelectromotive current of the thermocouple drops to a predetermined value due to natural cooling. Therefore, when the ignition push button is pressed shallowly to the extent that the ignition switch does not close during a short period of time after the extinguishing operation after the relatively quick water flow operation following the ignition operation, the electromagnetic safety valve opens. If this condition remains, gas leaks from the auxiliary burner because the shutoff valve opens, and gas is also released from the main burner when, for example, a water faucet is opened, causing an inconvenience. .

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 includes a changeover switch that operates in conjunction with manual opening of an electromagnetic safety valve interposed in the gas passages of the main burner and the sub-burner, and the changeover switch causes the solenoid of the safety valve to be connected to the capacitor. Switching from intervention in the charging circuit of the capacitor to intervention in the discharging circuit of the capacitor, the safety valve is opened by the discharge current of the capacitor and the electromotive current that reaches a predetermined value in the thermocouple facing the sub-burner. The apparatus is characterized in that a sub-discharge circuit for the capacitor is formed via a switch that is closed in conjunction with the opening operation of the main gas passage connected to the main burner.

(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 an auxiliary burner, and 3 is a gas passage that supplies combustion 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. The shutoff valve 5 and the electromagnetic safety valve 4 are pressed open by a manual operation member 8. To explain this in detail, the operation member 8 includes 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.
The operating rod 10 is provided with the shutoff valve 5, and the return spring 8b from the starting end position of the push button 8a is
According to the pressing operation against the pressure, the shutoff valve 5 is pressed open at the intermediate position of the pressing operation, and the electromagnetic safety valve 4 is pressed open via the lever 12 at the terminal position. The auxiliary burner 2 is composed of a pilot burner 2b and a constant flame burner 2a, and combustion 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 a 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
The combustion 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 the ignition switch 16a, which is closed at the pressed position past the intermediate position of the push button 8a. Operate.

The present invention relates to a circuit for controlling the safety valve 4 interposed in the gas supply path 3 of such a combustor.

FIG. 2 shows a circuit of this embodiment.

In the same figure, the solenoid 4a of the electromagnetic safety valve 4
In this case, the capacitor 17 is connected to the charging circuit 20 of the capacitor 17, which is connected to the power supply 19 through the movable contact 18c and the fixed contact 18a of the changeover switch 18, which are opened when the combustor is extinguished, and the charge charged in the capacitor 17 is charged. A movable contact 18c of the changeover switch 18 that is closed when the push button 8a is pressed.
The discharge circuit 21 is connected to a discharge circuit 21 that discharges electricity through the fixed contact 18b, and the discharge circuit 21 includes a fixed contact that constitutes a normally closed switch of a changeover switch 22 that operates in conjunction with the opening operation of the automatic valve 7. 22a and the movable contact 22c are interposed, and a resistor 23 is connected in parallel with the normally closed switch, and the fixed contact 22 constituting the normally open switch of the changeover switch 22
b and in series with the movable contact 22c, the capacitor 17
A resistor 26 is connected to one end of the capacitor 17, thereby forming a sub-discharge circuit 25 for the capacitor 17.

Next, its operation will be explained.

When the manual operation 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 opens by pushing the electromagnetic safety valve 4 at the terminal position. At the same time, the ignition switch 16a is closed. Therefore, the charge stored in the capacitor 17 begins to be discharged via the normally closed switch of the changeover switch 22 which intervenes in the discharge circuit 21, and the solenoid 4a is excited by this discharged 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 manual operation 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 release current value of the electromagnetic safety valve after a predetermined period of time has elapsed, but when combustion occurs normally in the sub-burner 2, a thermoelectromotive force is generated in the thermocouple 15. Therefore, 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 or a little later than the ignition operation without the auxiliary burner 2 ignited, the changeover switch 22 will open in conjunction with the opening of the automatic valve 7.
Since the normally closed switch is opened, and the normally open switch is closed, the charge in the capacitor 17 is transferred to the discharge circuit 21 in which the resistor 23 is interposed, and the resistor 26.
is discharged via the interposed sub-discharge circuit 25, the discharge current value of the capacitor 17 rapidly decreases.

As a result, the withdrawal current value that closes the electromagnetic safety valve 4 is quickly reached. Therefore, when the auxiliary burner 2 is not ignited, the electromagnetic safety valve 4 opens quickly, and the release of raw gas can be suppressed as much as possible.

On the other hand, if the sub-burner 2 is ignited but the thermocouple 15 is not generating a predetermined electromotive force and the water faucet is opened and the gas passage 3 to the main burner 1 is opened, the discharge current Since the composite current of the current and the thermoelectromotive current of the thermocouple 15 can be kept at or above the withdrawal current value of the electromagnetic safety valve 4, the electromagnetic safety valve 4 is maintained in an open state and does not close.

To extinguish the fire, press the fire extinguishing push button 24, the lock device 30 will be unlocked, the manual operating member 8 will be automatically returned by the return spring 8b, and this action will close the cutoff valve 5 and open both burners 1 and 2. The supply of fuel gas is cut off to extinguish the fire, and the return operation of the operating member 8 causes the changeover switch 18 to switch to the side that closes the charging circuit 20.

Next, for example, following the ignition of the auxiliary burner 2, water is supplied relatively quickly, then the water is stopped after a predetermined period of time, the extinguishing push button 24 is then pressed to extinguish the fire, and then for a short period of time. The operation when the ignition push button 8a is pressed and the pressing operation is particularly performed with a small amount of pressing will be described.

When the water flow operation is performed after the ignition operation and before the discharge of the capacitor 17 is completed, the residual charge in the capacitor 17 continues to be discharged by the discharge circuit 21 via the resistor 23 and also by the sub-discharge circuit 25 via the resistor 26. When the fire extinguishing push button 24 is pressed, a sufficiently large charging current flows from the power source 19, and the thermocouple 15 flows into the solenoid 4a due to residual heat.
The electromagnetic safety valve 4 immediately closes because the thermal electromotive current is canceled out.

In this way, even when the ignition push button 8a is repeatedly pressed within a short period of time after the fire extinguishing push button 24 is pressed to an extent that does not close the ignition switch 16a, there is no gas leakage from the sub-burner 2, and furthermore, the state is maintained. Gas is not released from the main burner 1 even when the person opens the faucet.

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 is 3.3F, the resistor 23 is 2.5Ω, and the resistor 2
6 has a value of 0.3Ω, and further not shown,
This is when a 1.3Ω resistor is inserted into the charging/discharging circuit of the capacitor 17.

In Figure 3, A(-x-) is solenoid 4
The charging/discharging current of the capacitor 17 flowing through a, B(-
o-) indicates the thermoelectromotive current of the thermocouple 15 flowing to the solenoid 4a, C(-) indicates the combined current of A and B flowing to the solenoid 4a, and the current value shown below the zero line is the thermoelectromotive current of the thermocouple 15 flowing to the solenoid 4a. and B, and the current value below the zero line indicates the polar current value flowing through the solenoid 4a from top to bottom in the figure.

According to FIG. 3, if water is supplied after 2 seconds after ignition when the capacitor 17 is not sufficiently discharged, then the 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 the solenoid 4a is 1.156, and the charging current flowing through it is 445 mA. . On the other hand, since the thermal electromotive current of the thermocouple 15 due to residual heat at the time of extinguishing the fire is 400 mA, the combined current is 45 mA, and the electromagnetic safety valve 4
The disconnection current value (100mA) or less when closing. . Therefore, the electromagnetic safety valve 4 closes almost simultaneously with the extinguishing operation.

Figure 6 shows the circuit disclosed in the above-mentioned Japanese Utility Model Publication No. 57-105529, with the same conditions as the circuit shown in Figure 2, and ignition, water flow, water shutoff, and extinguishing under the same conditions. The diagram shows the operating characteristics when

In the same figure, A', B', and C' are A, B, and C' in Figure 3.
Each corresponds to C. As is clear from this figure, according to the circuit disclosed in the publication, the combined current flowing through the solenoid of the electromagnetic safety valve at the time of extinguishing the fire is 110 mA, which is greater 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.

FIG. 4 shows a circuit diagram of another embodiment of the invention.
This circuit is a modification of the circuit shown in the second figure.
The resistor 26 of the illustrated circuit is connected to the resistor 23 in series with and via the normally closed contact of the changeover switch 22.
It is connected in parallel with. Since the resistor 26 suppresses the value of the discharge current flowing into the discharge circuit 21 via the normally closed contact of the changeover switch 22, there is an advantage that wear and tear associated with opening and closing of the contact can be reduced.

Other operations are similar to those shown in the second figure.
FIG. 5 shows yet another embodiment of the invention. This embodiment circuit does not require a normally closed switch that operates in conjunction with the opening operation of the automatic valve 7 as in the circuits shown in FIGS. 2 and 4 to operate the sub-discharge circuit 21.
A normally open switch 22A, which is closed in conjunction with the opening operation of the automatic valve 7, is inserted only in the valve 5. .

According to this circuit, unlike the circuits shown in FIGS. 2 and 4, the resistor 23 is not inserted into the discharge circuit 21, so that the charge in the capacitor 17 is more quickly discharged than in the circuits shown in FIGS. 2 and 4. Since the discharge occurs, the object of the present invention can be achieved more reliably than in the embodiments described above.

Note that since the above embodiment is applied to a water heater, the opening operation of the gas passage is 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.

In this way, according to the present invention, a changeover switch is provided that is linked to manual opening of the electromagnetic safety valve,
The changeover switch switches the solenoid of the safety valve from intervening in the capacitor charging circuit to intervening in the capacitor discharging circuit, and the discharging current of the capacitor and the heat generation of the thermocouple facing the sub-burner that has reached a predetermined value are switched. In the device in which the safety valve is held in an open state by electric current, a sub-discharge circuit for the capacitor is provided which is formed via a switch that is closed in conjunction with the opening operation of the main gas passage connected to the main burner. Therefore, after the ignition operation, for example, following the ignition of the auxiliary burner and before the discharge of the capacitor, the main gas passage is opened by, for example, water flow, and then after a predetermined time, the water is turned off, and then the fire extinguishing push button is pressed. Even if the ignition push button is pressed lightly to the extent that the ignition switch does not close during a short period of time before the electromotive force due to the residual heat of the thermocouple falls to a predetermined value, the electromagnetic safety valve will not close the ignition switch during extinguishing operation. The thermal electromotive current flowing through the solenoid is canceled by the capacitor's charging current and the valve closes, so there is no gas leakage from the auxiliary burner, and gas is also released from the main burner even when the water faucet is opened, for example. It has no effect.

[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.
4 is a circuit diagram of another embodiment of the present invention, FIG. 5 is a circuit diagram of still another embodiment of the present invention, and FIG. 6 is a diagram of a conventional circuit. The operating characteristic diagram, FIG. 7, shows a combustion control circuit of a conventional combustor. 1...Main burner, 2...Sub-burner, 3...Gas passage,
4... Solenoid safety valve, 4a... Solenoid of electromagnetic safety valve, 15... Thermocouple, 16... Igniter, 17... Capacitor, 16... Selector switch, 19... Power supply, 20...
Charging circuit, 21... Discharging circuit, 22... Changeover switch, 22A... Normally open switch, 24... Fire extinguishing push button,
23...Resistor, 25...Sub discharge circuit.

Claims (1)

[Claims] 1. A changeover switch is provided that is linked to manual opening of an electromagnetic safety valve interposed in the gas passages of the main burner and sub-burner, and the changeover switch switches the solenoid of the safety valve from intervention in the capacitor charging circuit to the capacitor discharge circuit. The safety valve is maintained in an open state by the discharge current of the capacitor and the electromotive current reaching a predetermined value of the thermocouple facing the secondary burner. A combustion control circuit for a combustor, characterized in that a sub-discharge circuit for the capacitor is formed via a switch that is closed in conjunction with an opening operation of a gas passage.