JPH0232535B2 - - Google Patents

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to a combustion control circuit for a combustor.

(Prior Art) Conventionally, this type of combustion control circuit includes a changeover switch linked to a manually operated member that can be switched between a closed position, an open position, and an ignition position, and the changeover switch switches the burner by operating the member from the closed position. The solenoid of the electromagnetic safety valve interposed in the gas passage connected to the unit is switched from intervening in the capacitor charging circuit to intervening in the capacitor discharging circuit, and by operating the member to the ignition position, the safety valve is pressed open and the burner unit is activated. The igniter is activated, and the pressure opening of the safety valve is released by operating the member to the open position. A device is known in which the safety valve is kept open, but the time required for the safety valve to remain open due to the discharge of the capacitor is limited to the time when the air in the gas passage is removed and the burner unit is closed after the member is operated to the ignition position. Since it requires a relatively long setting time, which includes the time required for the thermocouple to ignite and the time required for heating the thermocouple described above, the user does not immediately confirm ignition after operating the member to the ignition position. When the safety valve is operated to the open position, the safety valve is forced to remain open for a long time even though the burner unit is not ignited, resulting in the inconvenience that raw gas is released. Therefore, in order to solve this inconvenience, for example,
As shown in the above publication, it is desirable to insert a switch into the discharge circuit of the capacitor and open the switch when the member is in the open position to cut off the discharge current and close the safety valve.

(Problem to be Solved by the Invention) However, with the above method, the burner unit is ignited by pressing the manually operated member to the ignition position, and then the member is turned off at a relatively early point before the end of the discharge of the capacitor. When operated in the open position, a charge remains in the capacitor.

Therefore, even if the solenoid of the electromagnetic safety valve is inserted into the capacitor charging circuit during such a fire extinguishing operation and a charging current of opposite polarity to the thermal electromotive current due to the residual heat of the thermocouple is passed through the solenoid, a sufficiently large charging current will 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 lightly to the extent that the ignition switch does not close within a short period of time after such extinguishing operation, the cutoff valve opens, causing the inconvenience that raw gas is released from the burner unit. .

An object of the present invention is to provide a combustion control circuit for a combustor that does not have such disadvantages.

(Means for Solving the Problems) The present invention includes a changeover switch linked to a manually operated member that can be switched between a closed position, an open position, and an ignition position, and the changeover switch is operable from the closed position of the member. The solenoid of the electromagnetic safety valve interposed in the gas passage connected to the burner unit is switched from intervening in the capacitor charging circuit to intervening in the capacitor discharging circuit, and when the member is operated to the ignition position, the safety valve is pressed open. The igniter of the burner unit is activated, and the safety valve is maintained in an open state by a discharge current of the capacitor and a thermoelectromotive current of a thermocouple provided in the burner unit that has reached a predetermined value, The present invention is characterized in that a sub-discharge circuit for the capacitor is formed via a switch that is linked to the member and is closed in the open position.

(Example) Embodiments of the invention will be described with reference to the drawings.

In Fig. 1, 1 indicates a burner unit;
The burner unit 1 consists of a main burner 1a and a pilot burner 1b.

Reference numeral 2 denotes a gas passage that supplies fuel gas to the burner unit 1, and the gas passage 2 has an electromagnetic safety valve 3 and a cutoff valve 4 interposed therebetween, and these valves 3 and 4 can be set in a closed position and an open position. The valve is opened by pressing a manual operating member 5 that can be switched between the ignition position and the ignition position.To explain this in detail, the operating member 5 is a push button 5a provided on the operating panel 6 on the front side of the combustor; It is composed of a valve rod 5c extending rearward on the same axis and inserted into the gas passage 2, and a lever 5b at the rear end, and the valve rod 5c supports the shutoff valve 4 and , an ignition valve 7 consisting of a small diameter portion formed on the valve rod 5c is provided, and when the operating rod 5b is pushed against the return spring 8 from the illustrated closed position, the shutoff valve 4 is opened. The valve is switched to the final ignition position in which the shutoff valve 4 and the ignition valve 7 are opened, and the safety valve 3 is pressed open via the lever 5d. When the push operation is released at the ignition position, the return operation of the operating rod 5b by the return spring 8 is stopped at the open position by the stopper 10 that engages with the protrusion 9 on the outer periphery of the operating rod 5b, and the push button 5a side is stopped. The stopper 10 is returned to the closed position when the stopper 10 is released from the projection 9 by pressing the fire extinguishing button 11 arranged side by side.

The present invention relates to a control circuit for the safety valve 3 interposed in the gas passage 2 of such a combustor.
FIG. 2 shows a circuit of one embodiment.

In Fig. 2, the solenoid 3 of the electromagnetic safety valve 3
a is a movable contact 14c of the changeover switch 14, which is closed when the capacitor 13 is in the closed position of the manual operation member 5;
and a changeover switch which is connected to the charging circuit 16 of the capacitor 13 connected to the power source 15 via the fixed contact 14a, and which is closed when the manual operation member 5 is pressed from the closed position. 14 movable contacts 14c and fixed contacts 14
intervened in the discharge circuit 17 which is discharged via b;
The discharge circuit 17 includes a fixed contact 18a and a movable contact that constitute a normally open switch of a changeover switch 18 that is linked to the pressing operation of the manual operation member 5 and is closed when the manual operation member 5 is pressed to the ignition position. Contact 1
8c is intervened, and a resistor 19 is connected in parallel with the normally open switch, and the fixed contact 18b and the movable A resistor 23 connected to one end of the capacitor 13 is connected in series with the contact 18c to form a sub-discharge circuit 22 of the capacitor 13.

1 and 2, 12 is a thermocouple facing the burner unit 1, 20 is an igniter facing the pilot burner 1b, and 21 is a manual operation member 5.
This is an ignition switch that closes when pressed to the ignition position.

Next, its operation will be explained.

When the manual operating member 5 is pressed from the starting end position, the closed position, to the ending position, the ignition position, the changeover switch 14 is first switched from the charging circuit 16 side to the discharging circuit 17 side, and then the shutoff valve 4 is opened at the open position. At the ignition position, the ignition switch 21 is closed to operate the igniter 20, and at the same time as the electromagnetic safety valve 3 is pushed open, the normally open switch of the changeover switch 18 that intervenes in the discharge circuit 17 is closed. Therefore, the charge stored in the capacitor 13 is discharged through the normally open switch of the discharge circuit 17, and the solenoid 3a is excited by the discharged charge and keeps the safety valve 3 open. Therefore, burner unit 1
Fuel gas is supplied to the igniter 20, and is ignited by a spark generated by the igniter 20. Thereafter, when the pressing operation on the manual operation member 5 is released to return it to the open position, the normally closed switch of the changeover switch 18 is closed. Therefore, the electric charge of the capacitor 13 is discharged in the discharge circuit 17 via the resistor 19 and also in the sub-discharge circuit 22, so the current value decreases rapidly, and the withdrawal current value causes the electromagnetic safety valve 3 to close in a short time. reach.

Therefore, if the burner unit 1 is switched to the open position without ignition, the electromagnetic safety valve 3
The valve closes relatively quickly.

If the manual operation member 5 is returned to the open position when the burner unit 1 is ignited but the thermoelectromotive current of the thermocouple 12 has not reached a predetermined value, the discharge current value of the capacitor 13 will suddenly change as described above. However, when the thermoelectromotive current of the thermocouple 12 is added to the discharge current and the current can be maintained at or above the withdrawal current value of the electromagnetic safety valve 3, the electromagnetic safety valve 3 is kept open.

When the fire extinguishing push button 11 is pressed to extinguish the fire, the stopper 10 is disengaged from the protrusion 9, and the manual operating member 5 is automatically returned by the spring 8. During this operation, the shutoff valve 4 is closed and the burner unit is closed. Cut off the fuel gas supply to 1. When the manual operation member 5 returns to the closed position, the changeover switch 14 is switched to the side that closes the charging circuit 16, and a charging current flows through the solenoid 3a to cancel the thermoelectromotive current of the opposite polarity due to the residual heat of the thermocouple 12. , the electromagnetic safety valve 3 immediately closes.

Next, the manual operating member 5 is pressed to the ignition position to open the gas passage 2, and then the pressing operation is released at a relatively early stage before the discharge of the capacitor 13 ends to return to the open position, and then the gas passage 2 is returned to the open position. A case will be described in which the fire extinguishing push button 11 is pressed after a predetermined period of time has elapsed, and then the ignition push button 5a is pressed by a small amount to the extent that the igniter 20 is not activated within a short period of time.

Even when the manual operation member 5 is returned to the open position and the normally open switch of the changeover switch 18 is opened, the charge remaining in the capacitor 13 continues to be discharged through the resistor 19 and the changeover switch 1 is then closed.
Since the capacitor 13 is discharged through the normally closed switch 8 and no charge remains in the capacitor 13 during extinguishing operation, a sufficiently large charging current flows from the power source 15 to the solenoid 3a.

Therefore, this charging current is caused by the residual heat and the electromagnetic safety valve 3
As a result, the electromagnetic safety valve 3 immediately closes as a result of canceling out the thermoelectromotive current of the thermocouple 12 flowing through the solenoid 3a and reducing the current flowing through the solenoid 3a below the withdrawal current. Therefore, even if the ignition push button 5a is pressed to an extent that does not close the ignition switch 21 within a short time after the extinguishing operation and the manual operation member 5 is held in the open position, gas will still be released from the burner unit 1. Never.

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 13 is 3.3F, the resistor 19 is 2.5Ω, and the resistor 23 is 3.3F.
has a value of 0.3Ω, and this is when a resistor of 1.3Ω is further inserted in the charging/discharging circuit of the capacitor 13 (not shown).

In Figure 3, A(-x-) is solenoid 3.
The charging/discharging current of the capacitor 13 flowing through a, B(-
o-) indicates the thermoelectromotive current of the thermocouple 12 flowing to the solenoid 3a, C(-) indicates the combined current of A and B flowing to the solenoid 3a, and the current value shown below the zero line indicates the current value above the diagram in the solenoid 3a. Indicates the polarity current value flowing downward from .

According to FIG. 3, the manual operation member 5 is pressed to the ignition position, and after 2 seconds have elapsed since the capacitor 13 has not discharged much after ignition, it is turned to the open position, and then, after a predetermined period of time, for example, 5 seconds, the extinguishing push button 11 is pressed. When the member 5 is returned to the closed position, the voltage applied to the solenoid 3a at the time of extinguishing the fire is 0.98V, and the flowing charging current is 377mA. On the other hand, at the time of extinguishing the fire, the thermoelectromotive current of thermocouple 12 due to residual heat is 345 mA.
Therefore, the combined current is -32 mA, which is less than the withdrawal current value (100 mA) that closes the electromagnetic safety valve 3. Therefore, the electromagnetic safety valve 3 closes almost simultaneously with the extinguishing operation.

Figure 5 shows a conventional circuit in which a switch that is opened when the manual operating member is in the open position intervenes in the discharge circuit, with the common parts of the circuit shown in Figure 2 being the same, and the manual operating member being opened under the same conditions. The operating characteristic diagram when operated to the closed position and the closed position is shown. In the figure, A', B', and C' correspond to A, B, and C in FIG. 3, respectively.

As is clear from the figure, according to the conventional circuit,
The composite current C' flowing through the solenoid of the electromagnetic safety valve at the time of extinguishing the fire is 130 mA, which is greater than the withdrawal current.
Therefore, the electromagnetic safety valve 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 FIG. 2, in which the resistor 23 of the circuit shown in FIG. 2 is connected in series with the normally open switch 18 and in parallel with the resistor 19 via the normally open switch. be. Since the resistor 23 suppresses the value of the discharge current flowing to the discharge circuit 17 via the normally open switch of the circuit switch 18, there is an advantage that wear and tear associated with opening and closing of the normally open switch can be reduced.

Other operations are the same as those shown in the second figure.
In the above embodiment, the burner unit 1 is of a type equipped with the main burner 1a and the pilot burner 1b, but it can also be of a type equipped with a pilot burner for constant flame in addition to these burners. ,
Further, in the above embodiment, an ignition circuit is used as the igniter to ignite the vehicle, but a piezoelectric igniter may also be used for ignition. Furthermore, although the above embodiment is applied to a device having the cutoff valve 4 shown in the first diagram, since the electromagnetic safety valve 3 closes quickly when extinguishing a fire, the cutoff valve 4 can be omitted in some cases. There are advantages.

(Effects of the Invention) As described above, the present invention includes a changeover switch linked to a manually operated member that can be switched between a closed position, an open position, and an ignition position, and the changeover switch is operable from the closed position of the said member. The solenoid of the electromagnetic safety valve interposed in the gas passage connected to the burner unit is switched from intervening in the capacitor charging circuit to intervening in the capacitor discharging circuit, and when the member is operated to the ignition position, the safety valve is pressed open. In the safety valve, the safety valve is maintained in an open state by operating an igniter of the burner unit and using a discharge current of the capacitor and a thermoelectromotive current of a thermocouple provided in the burner unit that reaches a predetermined value. A sub-discharge circuit for the capacitor is provided, which is formed via a switch that is linked to the member and is closed in the open position, so that following the operation of the manually operated member to the ignition position, the discharge of the capacitor is completed before the discharge of the capacitor ends. Set the member to the open position at a relatively early point in time, then press the extinguishing push button after a predetermined time has elapsed, and further press the ignition push button before the thermoelectromotive current due to residual heat of the thermocouple falls to a predetermined value. This has the effect that raw gas is not released from the gas burner unit even when the amount of pressure is small.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a combustor 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 an operating characteristic diagram of a specific circuit, FIG. 4 shows a circuit diagram of another embodiment of the present invention, and FIG. 5 shows an operating characteristic diagram of a conventional circuit. DESCRIPTION OF SYMBOLS 1... Burner unit, 2... Gas passage, 3... Electromagnetic safety valve, 5... Manual operation member, 11... Fire extinguishing push button,
12... Thermocouple, 13... Capacitor, 14... Selector switch, 15... Power supply, 16... Charging circuit, 17... Discharging circuit, 18... Selecting switch, 22... Sub discharge circuit.

Claims (1)

[Claims] 1. Equipped with a changeover switch linked to a manually operated member that can be freely switched between a closed position, an open position, and an ignition position, and the changeover switch is operated from the closed position of the said member to open an electromagnetic safety valve interposed in a gas passage connected to the burner unit. Switch the solenoid from intervening in the capacitor charging circuit to intervening in the capacitor discharging circuit,
By operating the member to the ignition position, the safety valve is pressed open and the igniter of the burner unit is activated, and the discharge current of the capacitor and the thermoelectromotive current of the thermocouple provided in the burner unit that have reached a predetermined value are The safety valve is maintained in an open state, and is characterized in that a sub-discharge circuit for the capacitor is formed via a switch that is interlocked with the member and is closed in the open position. Combustion control circuit of combustor.