JPH0552327A - Combustion safety control device - Google Patents

Abstract

PURPOSE:To perform a positive shielding of a fuel supplying passage in the case where a combustion flame is not detected when a reignition is carried out just after a burner is turned off. CONSTITUTION:A combustion safety control device is comprised of a changing- over control circuit 607 for changing-over an electrical energized control state between the first electrical energization control circuit 605 for electrically controlling a safety valve 41 under an output from a flame rod 619 and the second electrical energization control circuit 606 for electrically controlling a safety valve 41 under an electromotive force of a thermocouple 640. The changing-over control circuit 607 controls the safety valve 4 with the first electrical energization control circuit 605 for a predetermined time after igniting operation and the safety valve 41 is controlled by the second electrical energization control circuit 606 after the predetermined time elapses. Thus, it is possible to avoid a valve opened holding state of the safety valve 41 with the electromotive force of the thermocouple 640 when the reignition is carried out just after the combustion is stopped.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a combustion safety control device for controlling an electromagnetic safety valve according to the output of a frame rod arranged near a burner and the electromotive force of a thermocouple.

[0002]

2. Description of the Related Art Conventionally, for example, in a gas combustion apparatus (Japanese Utility Model Publication No. 57-66457), a thermocouple is connected to a coil of an electromagnetic safety valve, and the electromagnetic safety valve is opened by electromotive force of the thermocouple. The safety valve is opened with another power source while detecting the presence of combustion flame with the flame rod for a certain period of time until the electromotive force of the thermocouple reaches the desired electromotive force with which the safety valve can be held open. A combustion safety control device is described that assists in valve retention.

[0003]

However, in the conventional combustion safety control device, when the gas burner is reignited (hot start) immediately after the gas burner is extinguished,
Especially when the thermocouple does not cool enough and the electromotive force of the thermocouple is generated, if the combustion flame does not occur in the gas burner due to poor ignition, or if the combustion flame disappears immediately after it occurs, the flame rod Even if it is not outputting, the electromagnetic safety valve is kept open due to the electromotive force output by the thermocouple. Therefore, even if the gas burner does not combust, the gas supply passage is not cut off, and raw gas flows out, which is a concern for safety.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a combustion safety control device for surely shutting off a fuel supply passage when a combustion flame is not detected when the burner is re-ignited immediately after extinguishing the burner.

[0005]

According to the present invention, there is provided an electromagnetic safety valve which is interposed in a fuel supply passage for supplying fuel to a burner and which opens when energized, and a frame for detecting the presence or absence of combustion flame generated in the burner. A first energization control circuit that has a rod and that energizes and controls the safety valve according to the output of the frame rod; and a thermocouple that produces an electromotive force due to the combustion flame of the burner, depending on the electromotive force of the thermocouple. A second energization control circuit for controlling energization of the safety valve, and the safety valve is controlled only by the first energization control circuit until a predetermined time elapses after ignition operation, and the second valve is operated after the predetermined time elapses. A technical means including a switching circuit for controlling the safety valve only by the energization control circuit is adopted.

[0006]

When the burner is ignited by the ignition operation, the electromagnetic safety valve is controlled only by the first energization control circuit until a predetermined time elapses after the ignition operation by the switching circuit. Regardless of the electric power, energization and stop of energization of the safety valve are controlled according to the output of the frame rod. Then, when a predetermined time has elapsed after the ignition operation, the switching circuit controls the electromagnetic safety valve only by the second energization control circuit, so that regardless of the output of the frame rod, only the electromotive force of the thermocouple energizes the safety valve. The stop of energization is controlled. Further, when the re-ignition operation is performed immediately after the combustion is performed by the burner, that is, even when the thermocouple is not completely cooled and the electromotive force is still generated from the thermocouple,
As described above, the safety valve is controlled only by the first energization control circuit by the switching circuit until a predetermined time has elapsed after the ignition operation. For this reason, when combustion flame is not detected by the burner by the frame rod, energization of the safety valve is stopped regardless of the electromotive force of the thermocouple, so that the fuel supply path is reliably shut off.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A combustion safety control device of the present invention is shown in FIGS.
A description will be given based on an example shown in FIG. FIG. 1 is a block diagram showing a combustion control unit of a gas combustion type water heater, and FIG. 2 is an electric wiring diagram showing a combustion control unit of the gas combustion type water heater. As shown in FIG. 3, the gas-fired water heater 1 includes a hot-water supply pipe 2 for discharging hot water or water, a gas pipe 4 for supplying a fuel gas to a gas burner 3, and a gas-fired water heater 1. A control device 5 is provided.

The hot water supply pipe line 2 comprises a water supply pipe 21, a heat absorption pipe 22 and a hot water discharge pipe 23. In the water supply pipe 21,
A water shutoff valve 24, a water governor valve 25, and a water amount adjusting valve 26 are provided. The water shutoff valve 24 opens when energized (ON) and closes when energized (OFF). The water governor valve 25 keeps the amount of water constant.
The water amount adjusting valve 26 controls the opening degree of the water supply pipe 21 by rotating a temperature adjusting button (not shown) to change the water amount. The heat absorbing tube 22 is disposed above the gas burner 3 and heats the water by exchanging heat between the water flowing inside and the combustion heat generated in the gas burner 3. The hot water discharge pipe 23 is formed of a flexible pipe and discharges hot water or water from the discharge port. A shower head 27 is fitted around the discharge port of the hot water discharge pipe 23. The shower head 27 switches the discharge flow discharged from the discharge port of the hot water discharge pipe 23 between the shower-like discharge flow and the straight-like discharge flow by switching a changeover switch (not visible in FIG. 3).

The gas line 4 is the fuel supply line of the present invention and comprises an electromagnetic safety valve 41, a water pressure responsive valve 42, a gas governor valve 43 and a gas amount adjusting valve 44. Safety valve 41
When the solenoid coil 410 is energized, the valve is opened to open the gas pipeline 4, and when the solenoid coil 410 is de-energized, the valve is closed to close the gas pipeline 4. Water pressure responsive valve 42
Is formed integrally with the water governor valve 25 and opens in conjunction with detection of a water flow. The gas governor valve 43 keeps the gas pressure on the secondary side constant. The gas amount adjusting valve 44 is connected to the temperature adjusting button, and controls the opening degree of the gas pipeline 4 by rotating the temperature adjusting button to change the gas amount.

As shown in FIG. 4, the control device 5 includes a combustion control unit 6, a water shutoff valve control unit 7, a power circuit 8,
A switching circuit 9, a changeover switch 10 and a water flow switch 11 are provided. The combustion control unit 6 is the combustion safety control device of the present invention, and incorporates a safety valve drive circuit 601, an ignition control circuit 602, and a combustion state detection circuit 603.

The safety valve drive circuit 601 has switching circuits 611 and 612, for example. Switching circuit 6
Reference numeral 11 denotes a circuit for supplying electric power to the safety valve 41, which is composed of, for example, a transistor 613 and resistors 614 and 615. This switching circuit 611 electrically connects the power supply circuit 8 and the solenoid coil 410 of the safety valve 41 when the input is at a low level (hereinafter referred to as L level), and supplies electric power to the solenoid coil 410. Further, the switching circuit 611 stops the supply of electric power to the solenoid coil 410 of the safety valve 41 when the input is at high level (hereinafter referred to as H level). The switching circuit 612 is
A circuit that determines the input level of the switching circuit 611.
For example, it is composed of a transistor 616 and resistors 617 and 618. When the input is at H level, the output is at L level, and when the input is at L level, the output is at H level. The ignition control circuit 602 controls ON / OFF of the sparker 604. The sparker 604 is for igniting a mixture of fuel gas and combustion air flowing out from the gas burner 3.

The combustion state detection circuit 603, as shown in FIG. 1, has a first energization control circuit 605 and a second energization control circuit 6.
06 and a switching control circuit 607. The first energization control circuit 605 includes a frame rod 619 and an oscillation circuit 62.
0, a flame detection circuit 621 and a switching circuit 622. The frame rod 619 is made of a heat-resistant metal, and is directly inserted into the combustion flame to detect the presence or absence of the combustion flame by the rectifying action of the combustion flame. The oscillator circuit 620 includes, for example, coils 623 and 624, a resistor 625, a diode 626.
And a transistor 627. When power is supplied, the output repeats H level and L level. The flame detection circuit 621 includes, for example, a coil 628, a Zener diode 629, capacitors 630 and 631, and resistors 632 and 6.
33, 634 and FET 635.
This flame detection circuit 621 is an FET when a combustion flame is formed and a current flows from the frame rod 619 to the gas burner 3 side.
The potential of the drain of 635 becomes L level, and the potential of the drain becomes H level if combustion flame does not occur. The coil 628 is combined with the coils 623 and 624 of the oscillation circuit 620 to form a transformer, and boosts an alternating current of 150 to 200V. The switching circuit 622 includes, for example, an inverter 636, a transistor 637 and a resistor 638,
639, the potential of the collector of the transistor 637 becomes H level when the input is L level, and the input is H level.
At the level, it becomes the L level.

The second energization control circuit 606 includes a thermocouple 640.
And, for example, a comparator 641 and resistors 642, 64
3, 644. The thermocouple 640 is a thermocouple composed of different kinds of metal wires, and detects thermoelectromotive force by the combustion flame to detect whether the gas burner 3 is in an abnormal combustion state such as an oxygen deficiency state of the combustion flame. Comparator 64
1 indicates that when the output voltage of the thermocouple 640 is lower than the set value (for example, 5 mV to 7 mV) determined by the resistors 642 and 643, the output becomes L level, and the output voltage of the thermocouple 640 rises above the set value. When it does, the output becomes H level. The output voltage of the thermocouple 640 generally takes 3 to 5 seconds to rise to the set value after the ignition operation.

The switching control circuit 607 is the switching circuit of the present invention, and is, for example, a timer circuit 645, a switching circuit 646, an electrolytic capacitor 647 and a diode 64.
It is composed of 8,649. The timer circuit 645 is
The output becomes L level until a predetermined time (for example, 20 seconds) elapses after the ignition operation is performed, and the output becomes H level after the predetermined time elapses. Switching circuit 646
Is a circuit for supplying power to the first energization control circuit 605,
For example, it is composed of a transistor 650 and resistors 651 and 652. The switching circuit 646 supplies power to the first energization control circuit 605 when the input is at L level. Further, the switching circuit 646 stops the supply of power to the first energization control circuit 605 when the input is at the H level. That is, the first energization control circuit 605 operates only for a predetermined time after the ignition operation is performed, and consumes electric power. The electrolytic capacitor 647 stabilizes the input voltage of the first energization control circuit 605.

The water shutoff valve control unit 7 holds an output of the infrared sensor 71, which is a reflection type photoelectric switch, and a water shutoff valve which controls the water shutoff valve 24 according to the output of the output hold circuit 72. It incorporates a valve drive circuit 73. The infrared sensor 71 includes a light emitting element 74 such as a photodiode that emits infrared rays, and a light receiving element 75 such as a phototransistor that detects infrared rays reflected by an object to be detected such as a user's hand. Output holding circuit 72
The output becomes high level (H level) when the light receiving element 75 detects infrared ray, and becomes low level (L level) when the light receiving element 75 detects infrared ray again. The water stop valve drive circuit 73 turns on and opens the water stop valve 24 when the input is at the H level, and turns off and closes the water stop valve 24 when the input is at the L level.

The power supply circuit 8 uses, for example, a 3V dry battery, and a water flow switch 11 for indicating that water is flowing later.
Is detected and the hot water mode is selected and the changeover switch 10 is turned on, the electromagnetic safety valve 41, the safety valve drive circuit 601, the first energization control circuit 605, the second energization control circuit 6
06 and the switching control circuit 607 can be supplied with electric power. The switching circuit 9 is composed of one transistor and is connected in series between the combustion control unit 6 and the power supply circuit 8. The switching circuit 9 turns on when the input is at the H level and turns off when the input is at the L level. The changeover switch 10 is a switch that switches between the hot water mode and the water mode, and is connected in series between the combustion control unit 6 and the switching circuit 9. The changeover switch 10 is turned on (contact is closed) when the user selects the hot water mode, and is turned off (contact is opened) when the water mode is selected. The water flow switch 11 is connected in series between the combustion control unit 6 and the changeover switch 10. The water flow switch 11 is a switch that is turned on when the water pressure responsive valve 42 detects a water flow and opens, and is turned off when it is closed.

The operation of the combustion control unit 6 of the gas combustion type water heater will be described with reference to FIGS. 1 to 5. When the water flow switch 11 is turned on and the changeover switches 10 are both turned on (hot water mode selection), the safety valve 41 is forcibly held open for a short time. Therefore, the fuel gas is supplied to the gas burner 3 through the gas pipe 4 and ignited, and
As shown in (a)), combustion is started in the gas burner 3.

When combustion is started in the gas burner 3, the output of the timer circuit 645 of the switching control circuit 607 becomes L level until a predetermined time t1 (for example, 20 seconds) elapses, as shown in (a) of FIG. Become. Thus, when the output of the timer circuit 645 is at the L level, the switching circuit 6
Since the input of the 46th transistor 650 becomes L level, the transistor 650 is turned on. Therefore, the power supply circuit 8
Since electric power is supplied to the first energization control circuit 605 from the first energization control circuit 605, the first energization control circuit 605 starts operating simultaneously with the start of combustion. Here, the gas burner 3 is connected by the frame rod 619.
When the combustion flame generated in
A current flows from 9 toward the combustion flame, and the gate of the FET 635 has a negative potential. That is, it is determined that the flame rod 619 has detected the combustion flame in the flame detection circuit 621. Then, when the gate of the FET 635 becomes a negative potential,
Since the drain potential of the FET 635 becomes H level,
The input of the inverter 636 becomes H level, and the inverter 636 outputs L level output. Therefore, the base potential of the transistor 637 of the switching circuit 622 becomes L level, so that the transistor 637 is turned on.

Therefore, since the output of the switching circuit 622 becomes the H level, the transistor 616 of the switching circuit 612 of the safety valve drive circuit 601 is turned on and the transistor 613 of the switching circuit 611 is turned on. For this reason, electric power is supplied from the power supply circuit 8 to the solenoid coil 410 of the safety valve 41, so that the solenoid coil 410 of the safety valve 41 is turned on and the safety valve 41 is held open as shown in FIG. Therefore, since the gas pipeline 4 is opened, the supply of the fuel gas to the gas burner 3 is continued, so that the combustion of the gas burner 3 is continued.

On the other hand, since the second energization control circuit 606 is constantly supplied with electric power from the power supply circuit 8, if the gas burner 3 is in normal combustion some time after the ignition operation, the operation shown in FIG. As shown in, the output voltage of the thermocouple 640 rises above the set value. Then, the comparator 64
1 becomes H level, but the output of the timer circuit 645 is L level, that is, until a predetermined time elapses after the ignition operation, the H level output of the comparator 641 passes through the diode 648 and passes the timer. The circuit 645 is sucked. Therefore, the output of the second energization control circuit 606 is the safety valve 41 until a predetermined time has elapsed after the ignition operation.
Therefore, the opening and closing of the safety valve 41 is controlled only according to the output of the frame rod 619. When a predetermined time has elapsed after the ignition operation, the output of the timer circuit 645 becomes H level, as shown in (a) of FIG. Therefore, the transistor 650 of the switching circuit 646 is
Since the electric potential of the base of the transistor becomes H level, the transistor 65
0 turns off. Therefore, the supply of power from the power supply circuit 8 to the first energization control circuit 605 is stopped, so that the first energization control circuit 605 stops operating. That is, as shown in (c) of FIG. 5, the frame rod 619 is forcibly turned off, and the power consumption of the first energization control circuit 605 including the frame rod 619 is eliminated. Therefore, when the thermocouple 640 detects the normal combustion of the gas burner 3, the H level output of the comparator 641 is sent to the safety valve drive circuit 601 through the diode 649. Therefore, after the predetermined time has elapsed, the first energization control circuit 6
Since electric power is not supplied to 05, the opening and closing of the safety valve 41 is controlled only according to the electromotive force of the thermocouple 640.

Further, as shown in (a) of FIG. 5, when the re-ignition operation is performed immediately after the combustion by the gas burner 3 (for example, after t2 = 10 seconds), the thermocouple 640 does not cool down and the comparator 641 is still available. The output of may be H level.
Even in such a case, the output of the timer circuit 645 is at the L level until a predetermined time elapses after the ignition operation, as shown in (a) of FIG. Therefore, as described above, the output of the comparator 641 is sucked by the timer circuit 645, so that the output of the second energization control circuit 606 is not sent to the safety valve 41. Therefore, when the combustion burner is not detected by the gas burner 3 due to poor ignition, the flame detection circuit 6 does not have a rectifying function of the combustion flame by the frame rod 619.
The drain potential of the FET 635 of No. 21 becomes an L level output. Therefore, the transistor 637 is turned off, the input of the transistor 616 becomes L level, and both the transistors 613 and 616 are turned off. Therefore, the supply of power from the power supply circuit 8 to the solenoid coil 410 of the safety valve 41 is stopped, and the safety valve 41 is closed.
As a result, the gas pipeline 4 is reliably shut off, so that no raw gas is released from the gas burner 3.

As described above, the combustion control unit 6 of the gas-fired water heater 1 operates the gas pipe 4 regardless of the output of the thermocouple 640 when the gas burner 3 is reignited immediately after the fire is extinguished. It can shut off surely. As a result, the safety can be improved, so that the combustion control unit 6 of the gas-fired water heater 1 having high reliability can be provided. Further, since ignition is detected by the frame rod 619 until a predetermined time has elapsed after the ignition operation, the ignition can be detected earlier than when only the thermocouple 640 is attached. Therefore, the time during which the safety valve 41 is forcibly opened and held can be shortened, and the raw gas will not be released from the gas burner 3 when the ignition error occurs. Since the supply of electric power to the first energization control circuit 605 is stopped after a lapse of a predetermined time after the ignition operation, the consumption of the battery can be reduced when a battery is used in the power supply circuit 8, for example. .. Further, after a predetermined time has passed from the ignition operation, the thermocouple 640
Since the safety valve 41 is energized and controlled in accordance with the output of, the abnormal combustion such as oxygen deficiency can be detected.

(Modification) The first energization control circuit, the second energization control circuit and the switching circuit may be composed of one or more microcomputers. Further, the switching circuit may be composed of a timer circuit and a relay switch. Further, the first energization control circuit, the second energization control circuit or the switching circuit can be variously modified without departing from the scope of the present invention. In this embodiment, the infrared sensor 71 is provided as a device that outputs a valve opening signal to the water shutoff valve 24, but another output device such as a touch switch may be provided. The present invention may be used in a combustion safety control device for a combustion device such as a water heater, a heater or a stove that burns liquid fuel.

[0024]

According to the present invention, when the flame is not detected by the flame rod when the burner is re-ignited immediately after the burner is extinguished, the fuel supply passage can be reliably shut off regardless of the electromotive force of the thermocouple. Therefore, since safety can be improved, a highly reliable combustion safety control device can be provided.

[Brief description of drawings]

FIG. 1 is a block diagram showing a combustion control unit of a gas combustion type water heater.

FIG. 2 is an electrical wiring diagram showing a combustion control unit of a gas combustion type water heater.

FIG. 3 is a schematic view showing a gas combustion type water heater.

FIG. 4 is a block diagram showing a control device for a gas combustion type water heater.

FIG. 5 is a time chart of a frame rod, a thermocouple, and the like.

[Explanation of symbols]

 3 Gas Burner 4 Gas Pipe Line (Fuel Supply Line) 6 Combustion Control Unit (Combustion Safety Control Device) 41 Electromagnetic Safety Valve 605 First Energization Control Circuit 606 Second Energization Control Circuit 607 Switching Control Circuit (Switching Circuit) 619 Frame Rod 640 Thermoelectric versus

Claims (1)

[Claims] 1. An electromagnetic safety valve interposed between a fuel supply passage for supplying fuel to a burner and opened when energized, and (b) a flame rod for detecting the presence or absence of a combustion flame generated in the burner. And a first energization control circuit that energizes and controls the safety valve according to the output of the frame rod; and (c) a thermocouple that produces an electromotive force due to the combustion flame of the burner. A second energization control circuit for controlling energization of the safety valve in accordance therewith; (d) the safety valve is controlled only by the first energization control circuit until a predetermined time elapses after ignition operation, and after the predetermined time elapses Is a combustion safety control device including a switching circuit that controls the safety valve only by the second energization control circuit.