JPH08145355A - Combustion control device - Google Patents

Abstract

PURPOSE: To perform reliable extinction of the flame of a burner in relation to even complex abnormal operation of a microcomputer and to prevent leakage of fuel through the stop of the feed of fuel. CONSTITUTION: A fuel feed passage is opened and closed by a solenoid valve, energization to the solenoid valve is controlled by means of relays 22, 23, and 24, and the relays 22, 23, and 24 are controlled by a microcomputer 19. A switch means operation permitting means 21 permits operation of the relays 22, 23, and 24 only when a pulse signal of a constant period is inputted. The microcomputer 19 outputs a pulse signal, of a constant period from a port 19d to the switch means operation permitting means 21 according to a prestored program.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a combustion control device using a microcomputer, which is used in various combustion equipment such as a water heater and a heater.

[0002]

2. Description of the Related Art As a conventional combustion control device using a microcomputer, as described in, for example, Japanese Patent Laid-Open No. 3-156210, a flame detecting element for detecting the flame of a burner is provided, and a fuel from the microcomputer is provided. It is known that the fuel supply is continued by a logical product signal of the continuation signal and the flame detection signal from the flame detection element.

[0003]

In the conventional combustion control device, the fuel supply can be stopped when the flame disappears, but the fuel supply is stopped when the operation of the microcomputer is abnormal. There is a problem that it may not be possible to secure a safe and reliable fire extinguishing in the event of an abnormality. Although a combustion control device that provides a safety measure against abnormal operation of a microcomputer has also been proposed, for safety reasons, even if the abnormal operation of a microcomputer is complicated, the fire must be extinguished reliably and the fuel must be removed. It is necessary to stop the supply.

The present invention has been proposed in view of the above points, and it is possible to reliably extinguish the burner and stop the fuel supply to prevent a fuel leak even in the case of a complex abnormal operation of the microcomputer. Its purpose is to prevent.

[0005]

In order to solve the above problems, the present invention takes the following technical means.

That is, the invention according to claim 1 of the present application comprises an electromagnetic valve for opening and closing the fuel supply path, a switch means for controlling energization of the electromagnetic valve, and a microcomputer for controlling the switch means. The combustion control device is provided with a switch means operation permitting means that enables the switch means to operate only when a pulse signal of a constant cycle is input, and based on a program stored in advance by the microcomputer. By outputting a pulse signal of a constant cycle to the switch operation permitting means by means of a solenoid valve, the fuel supply path can be opened by the solenoid valve only while the pulse signal of a constant cycle is being output. I am trying.

Further, the invention described in claim 2 of the present application is
A water amount sensor that detects the amount of water supplied to the heat exchanger, a solenoid valve that opens and closes the fuel supply path, switch means that controls energization of the solenoid valve, and a microcomputer that controls the switch means are provided. A combustion control device,
A switch means operation permitting means that enables the switch means to operate only when the amount of water detected by the water amount sensor is equal to or greater than a predetermined amount and a pulse signal of a constant cycle is input is provided and stored in advance by the microcomputer. By outputting a pulse signal of a constant cycle to the switch operation enabling means based on a program, the amount of water supplied to the heat exchanger is equal to or more than a predetermined amount, and the pulse signal of a constant cycle is output only. It is characterized in that the fuel supply passage can be opened by the solenoid valve.

The invention described in claim 3 of the present application is
A combustion control device including a flame detector for detecting a flame of a burner, a solenoid valve for opening and closing a fuel supply path, a switch means for controlling energization of the solenoid valve, and a microcomputer for controlling the switch means. There is a switch means operation that enables the switch means to operate only when the flame detector detects a flame and a pulse signal of a constant cycle is input except for a fixed time from the start of ignition. By providing a permitting means and outputting a pulse signal of a constant cycle to the switch means actuation permitting means on the basis of a program stored in advance by the microcomputer, the burner flame exists except for a fixed time from the start of ignition. Cage,
The fuel supply passage is opened by the solenoid valve only during the period when the pulse signal of a constant cycle is output.

[0009]

According to the first aspect of the invention, the solenoid valve opens and closes the fuel supply passage, the switch means controls energization of the solenoid valve, and the microcomputer controls the switch means. Further, the switch device operation permitting device enables the switch device to operate only when a pulse signal having a constant cycle is input. Then, the microcomputer outputs a pulse signal having a constant cycle to the switch operation permitting means based on a program stored in advance. Therefore, the fuel valve can be opened by the solenoid valve only while the microcomputer outputs the pulse signal of a constant cycle. As a result, regardless of whether the output is maintained at a high level or a low level due to abnormal operation of the microcomputer, the operation of the switch means is prohibited by the switch means operation permitting means, and the fuel by the solenoid valve is used. The cutoff state of the supply path is maintained.

According to the invention described in claim 2, the amount of water supplied to the heat exchanger is detected by the water amount sensor,
The solenoid valve opens and closes the fuel supply path, the switch means controls energization of the solenoid valve, and the microcomputer controls the switch means. Further, the switch means operation permitting means enables the switch means to operate only when the amount of water detected by the water amount sensor is equal to or more than a predetermined amount and a pulse signal having a constant cycle is input. Then, the microcomputer outputs a pulse signal having a constant cycle to the switch operation permitting means based on a program stored in advance. Therefore, only when the amount of water supplied to the heat exchanger is equal to or greater than a predetermined amount and the pulse signal of a constant cycle is output from the microcomputer,
It is possible to open the fuel supply path by the solenoid valve. As a result, whether the output is maintained at a high level or a low level due to an abnormal operation of the microcomputer or the amount of water supplied to the heat exchanger is less than a predetermined amount, in any case. The operation of the switch means is prohibited by the switch means operation permitting means, and the shutoff state of the fuel supply path by the solenoid valve is maintained.

According to the third aspect of the present invention, the flame detector detects the flame of the burner, the solenoid valve opens and closes the fuel supply path, and the switch means controls the energization of the solenoid valve. Controls the switch means. In addition, the switch means operation permitting means,
The switch means can be operated only when the flame detector detects a flame and a pulse signal of a constant cycle is input for a certain period of time from the start of ignition. Then, the microcomputer outputs a pulse signal of a constant cycle to the switch means operation permitting means based on a program stored in advance. Therefore, the burner flame is present for a certain period of time from the start of ignition, and the fuel valve can be opened by the solenoid valve only during the period when the microcomputer outputs a pulse signal of a certain cycle. . As a result, even if the output is maintained at high level or low level due to abnormal operation of the microcomputer, or even if the burner flame does not exist except for a certain time from the start of ignition, However, the operation of the switch means is prohibited by the switch means operation permitting means, and the shutoff state of the fuel supply path by the solenoid valve is maintained.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The preferred embodiments of the present invention will be described below.
A specific description will be given with reference to the drawings.

(Embodiment 1) FIG. 2 shows Embodiment 1 of the present invention.
FIG. 2 is a schematic configuration diagram of a water heater including the combustion control device according to the first embodiment, in which a burner 2 for generating a flame is provided inside a casing 1.
A fuel supply path 3 for supplying a fuel such as gas or oil to the burner 2, a heat exchanger 4 for giving heat from combustion of the fuel to water to turn it into hot water, and water passing through the heat exchanger 4. Waterway 5
Are installed, and the fuel supply path 3 has solenoid valves 6,
7, 8 are interposed. In the vicinity of the burner 2,
A flame detector 9 for detecting the flame of the burner 2 is installed. A fan motor 12 that drives a sirocco fan for supplying secondary air to the inside of the casing 1 is installed inside a fan case 11 that is continuous with the lower end of the casing 1. An igniter 13 for igniting the burner 2 is installed outside the casing 1, and a water amount sensor 14 for detecting the amount of water flowing through the water passage 5 is provided in the water passage 5.
And a thermistor 15 for detecting the incoming water temperature. Further, detection signals are input to the outside of the casing 1 from the flame detector 9, the water amount sensor 14, and the thermistor 15, and the controller 16 for controlling the solenoid valves 6, 7, 8 and the fan motor 12, the igniter 13, and the remote operation. And a remote controller 17 for are installed.

FIG. 1 is an electric circuit diagram of a main part of the controller 16. Inside the controller 16, detection signals from the flame detector 9, the water amount sensor 14, the thermistor 15 and the like are input, and the solenoid valves 6 and 6. Microcomputer 19 for outputting signals for controlling 7, 8 and fan motor 12, igniter 13 and the like, and a constant voltage circuit 2 with a reset function for supplying the microcomputer 19 with power of a predetermined voltage.
0, switch means operation permitting means 21 for enabling a relay, which will be described later, which constitutes the switch means, to operate only when a pulse signal of a constant cycle is inputted from the microcomputer 19, and the solenoid valves 6, 7. Relays 22, 23, 2 forming switch means for controlling energization to
4, the diodes 26, 27, 28 and the transistor 2
9, 30, 31 and resistors 32, 33, 34 are installed. The switch means operation permitting means 21 includes transistors Q1 and Q2, capacitors C1 and C2, a diode D1, and resistors R1 to R6.

The input terminal of the constant voltage circuit 20 is a DC power source Vcc.
The output terminal of the constant voltage circuit 20 is connected to the power supply port 19a of the microcomputer 19. The reset end of the constant voltage circuit 20 is connected to the reset port 19b of the microcomputer 19, and the ground port 19c of the microcomputer 19 is grounded. The port 19d of the microcomputer 19 is connected to the base of the transistor Q1 via the resistor R1, and the emitter of the transistor Q1 is grounded.
One end of the resistor R2 is connected to the base of the transistor Q1 and the other end of the resistor R2 is connected to the emitter of the transistor Q1. The collector of the transistor Q1 is connected to the base of the transistor Q2 via the resistor R3, the capacitor C1 and the resistor R5. The emitter of the transistor Q2, one end of the resistor R6, the capacitor C2
, A cathode of the diode D1, and one end of the resistor R4 are connected to the DC power source Vcc, respectively.
The other end of 6 is connected to the connection point between the base of the transistor Q2 and the resistor R5. The other end of the capacitor C2 and the anode of the diode D1 are connected to the resistor R5 and the capacitor C1.
And the other end of the resistor R4 is connected to the connection point between the capacitor C1 and the resistor R3.
The collectors of the transistor Q2 are relays 22, 23, 2
One end of the coil of No. 4 and the cathodes of the diodes 26, 27, 28 are connected, and the diodes 26, 27, 2 are connected.
The anode of 8 is connected to the other ends of the coils of the relays 22, 23, 24. The other ends of the coils of the relays 22, 23, 24 are connected to the collectors of the transistors 29, 30, 31 and the emitters of the transistors 29, 30, 31 are grounded via the resistors 32, 33, 34. The bases of the transistors 29, 30, 31 are connected to the ports 19e, 19f, 19g of the microcomputer 19. The capacitor C1 constitutes a part of the differentiating circuit, and the capacitor C2 constitutes a part of the integrating circuit.

FIG. 3 is an electric circuit diagram of a main part of a water heater equipped with the combustion control device according to the first embodiment of the present invention. Inside the controller 16, an AC power supply 36 and a relay (not shown) are provided. The normally open contact 37, the rectifier 38, and the power supply circuit 39 that generates the DC power supply Vcc are installed.
Series circuit of igniter 13 and normally open contact 37 and rectifier 3
The parallel circuit of 8 and the power supply circuit 39 is connected to the AC power supply 36, and one end on the output side of the rectifier 38 is connected to one end of the normally open contact 22a of the relay 22. The other end of the normally open contact 22a of the relay 22 is connected to one end of the solenoid 6a of the solenoid valve 6, one end of the normally open contact 23a of the relay 23, and one end of the normally open contact 24a of the relay 24. The other end of the normally open contact 23a of the relay 23 is connected to one end of the solenoid 7a of the solenoid valve 7, and the other end of the normally open contact 24a of the relay 24 is connected to one end of the solenoid 8a of the solenoid valve 8. The other ends of the solenoids 6a, 7a, 8a of the solenoid valves 6, 7, 8 are connected to the other end on the output side of the rectifier 38.

Next, the operation will be described. The operation command from the remote controller 17 is input to the controller 16,
When a detection signal indicating that a predetermined amount or more of water is detected is input from the water amount sensor 14 to the microcomputer 19, the microcomputer 19 starts the processing of the main routine, and the microcomputer 19 stores it in advance. Based on the program, the port 19d outputs a pulse signal having a constant cycle as shown in FIG. For example, at the start of processing of the main routine, port 1
9d goes high, the port 19d goes low at the end of the main routine processing, and when the timer by the software that starts the timing operation from the start of the processing of the main routine times out, the main routine again starts. The operation that the port 19d becomes high level at the same time when the processing is started is repeated. When the pulse signal from the port 19d of the microcomputer 19 becomes high level, the transistor Q1 is turned on and a current flows through the capacitors C2 and C1, as shown in FIG. 4B,
The current flowing through the capacitor C1 sharply decreases with time as shown in FIG. 4C, and the voltage across the capacitor C2 gradually increases with time as shown in FIG. 4D. As a result, the voltage between the base and the emitter of the transistor Q2 exceeds a predetermined level, and the transistor Q2 is turned on as shown in (e) of FIG. As a result, the DC power supply Vcc is applied to one ends of the coils of the relays 22, 23, 24. When the pulse signal output from the port 19d of the microcomputer 19 becomes low level, the transistor Q1 is turned off, the charge of the capacitor C1 is discharged through the diode D1 and the resistor R4, and the charge of the capacitor C2 is changed. Transistor Q
Discharge through the emitter-base of 2 and the resistor R5. Therefore, the discharge state of the capacitor C2 keeps the transistor Q2 on, and the pulse signal is inverted to a high level before the transistor Q2 is turned off. As a result, the transistor Q2 always maintains the ON state while the pulse signal is repeatedly turned on and off at a constant cycle.

When the port 19e of the microcomputer 19 goes high as shown in FIG. 4 (f), the transistor 29 is turned on and the coil of the relay 22 is energized. As a result, the normally-open contact 22a of the relay 22 is closed, and the solenoid 6a of the solenoid valve 6 is energized.
The solenoid valve 6 is opened as shown in FIG. When the ports 19f and 19g of the microcomputer 19 become high level, the transistors 30 and 31 are turned on, the coils of the relays 23 and 24 are energized, and the normally open contacts 23a and 24a of the relays 23 and 24 are closed. The solenoids 7a and 8a of the solenoid valves 7 and 8 are energized to open the solenoid valves 7 and 8. Therefore, the fuel passes through the fuel supply passage 3 and the burner 2
Is supplied to. In this state, the microcomputer 19 controls a relay (not shown) to close the normally open contact 37, energize the igniter 13 and ignite the burner 2. As a result, the water in the water channel 5 is heated while passing through the heat exchanger 4, and is supplied to a predetermined place. Of course, only one of the solenoid valves 7 and 8 can be opened by setting only one of the ports 19f and 19g of the microcomputer 19 to a high level according to the amount of hot water supplied and the temperature of hot water supplied.

If an abnormality occurs in the operation of the microcomputer 19 and the ports 19e, 19f, 19g, etc. remain at the high level and the port 19d remains at the low level, the discharge of the capacitor C2 is completed. Also, since the transistor Q1 does not turn on, the transistor Q2 turns off, and the coil of the relays 22, 23, 24 receives the DC power supply V
cc is no longer applied. This allows relays 22 and 2
3, 24 normally open contacts 22a, 23a, 24a are opened,
The energization of the solenoids 6a, 7a, 8a of the solenoid valves 6, 7, 8 is cut off, and the solenoid valves 6, 7, 8 are closed. vice versa,
If the port 19d of the microcomputer 19 maintains a high level state, the potential at the connection point between the capacitor C1 and the resistor R5 rises as the capacitor C1 is charged, and the potential difference between the base and the emitter of the transistor Q2 increases. It gets smaller and finally transistor Q2 turns off,
DC power supply Vcc is not applied to the coils of relays 22, 23, 24. As a result, the normally open contacts 22a, 23a, 24a of the relays 22, 23, 24 are opened, and the solenoid valves 6,
The energization of the solenoids 6a, 7a, 8a of 7, 8 is cut off, and the solenoid valves 6, 7, 8 are closed. Even if the transistor Q1 is short-circuited, the microcomputer 1
The solenoid valves 6, 7 and 8 are closed by the same operation as when the port 19d of 9 maintains a high level state.

As described above, due to the abnormal operation of the microcomputer 19, whether the output of the port 19d is maintained at the high level or the low level while the ports 19e, 19f and 19g are maintained at the high level, Also in this case, since the transistor Q2 is turned off, the solenoid valves 6, 7, 8 can be surely closed. Therefore, the fire can be surely extinguished, and the leakage of the fuel from the burner 2 can be surely prevented.

In the first embodiment, the supply of the DC power supply Vcc to the relays 22, 23, 24 was controlled by the switch operation permitting means 21, but instead of this, an ON signal is output from the port 19e of the microcomputer 19. It is also possible to output a pulse signal of a constant cycle, connect the switch means operation permitting means 21 to the port 19e, and directly drive the relay 22 by the switch means operation permitting means 21. Further, two switching means operation permitting means 21 may be provided, and the control of the supply of the DC power supply Vcc to the relays 22, 23, 24 and the control of the relay 22 may be used together. Further, the relays 23 and 24 may also be configured to be controlled by the switch operation permitting means 21.

(Second Embodiment) FIG. 5 shows a second embodiment of the present invention.
FIG. 2 is an electric circuit diagram of a main part of a controller provided in the combustion control device according to the first embodiment, and is different from the circuit of the first embodiment shown in FIG. . That is, the transistor Q2
Collector and port 19h of microcomputer 19
, And a parallel circuit of a relay 41 and a diode 42 is connected between them, and one ends of coils of the relays 22, 23, 24 and cathodes of the diodes 26, 27, 28 are connected to a DC power supply Vcc. The other end of the coil of the relay 41 is connected to the collector of the transistor 43, and the base of the transistor 43 is connected to the port 19h of the microcomputer 19. The emitter of the transistor 43 is grounded via the resistor 40.

FIG. 6 is an electric circuit diagram of a main part of a water heater equipped with a combustion control device according to a second embodiment of the present invention. The difference from the circuit of the first embodiment shown in FIG. The point is that the normally open contact 41 a of the relay 41 is connected between the 36 and the normally open contact 37.

In the second embodiment, the transistor Q2 is turned on by the same operation as in the first embodiment, as shown in FIG.
When the port 19h of the microcomputer 19 becomes high level as shown in (f), the coil of the relay 41 is energized and the normally open contact 41a of the relay 41 is closed. As a result, when the rectifier 38 is connected to the AC power supply 36 and the normally open contacts 22a, 23a, 24a of the relays 22, 23, 24 are closed, the solenoid valves 6, 7, 8 of the solenoid valves 6a, 7a, 7a, 7a, 7a are closed.
The solenoid valves 6, 7 and 8 are opened by energizing a and 8a. Here, if an abnormality occurs in the operation of the microcomputer 19 and the transistor Q2 is turned off by the same operation as in the first embodiment, the coil of the relay 41 is no longer energized as shown in (g) of FIG. The normally open contact 41a is opened. Therefore, the connection between the AC power supply 36 and the rectifier 38 is cut off, and the solenoids 6a, 7 of the solenoid valves 6, 7, 8 are
The solenoid valves 6, 7 and 8 are closed because the a and 8a are not energized. Note that FIG. 7A shows the microcomputer 1
9 shows the voltage waveform of the port 19d, FIG. 7 (b) shows the on / off state of the transistor Q1, and FIG. 7 (c) shows the capacitor C1.
7D, the waveform of the voltage across the capacitor C2 is shown in FIG. 7D, and the on / off state of the transistor Q2 is shown in FIG. 7E.

As described above, regardless of whether the output of the port 19d is maintained at the high level or the low level due to an abnormal operation of the microcomputer 19, the transistor Q2 is turned off in any case, so that the solenoid valve can be reliably operated. 6,
The valves 7 and 8 can be closed. Therefore, the fire can be surely extinguished, and the leakage of the fuel from the burner 2 can be surely prevented. Further, since the energization of the igniter 13 is also blocked, sparks for ignition do not occur.
Further, the switch 41 actuation enabling means 21 causes the relay 41
Since the normally open contact 41a of the relay 22 is opened,
Even when the normally open contacts 3 and 24 are stuck and closed, the solenoid valves 6, 7 and 8 can be reliably closed.

In the second embodiment, the relay 41 is controlled by the switch operation permitting means 21.
1 is not provided, and the port 19 of the microcomputer 19 is provided.
A pulse signal having a constant cycle is output as an ON signal from e, and the switch means operation permitting means 21 is output to this port 19e.
May be connected to drive the relay 22 directly by the switch operation permitting means 21. Also, two systems of switch means operation permitting means 21 are provided, and the relay 4
The control of No. 1 and the control of the relay 22 may be used together. Further, the relays 23 and 24 may also be configured to be controlled by the switch operation permitting means 21.

Although the normally open contact 41a of the relay 41 is provided on the input side of the rectifier 38 in the second embodiment, the normally open contact 41a may be provided on the output side of the rectifier 38.

(Third Embodiment) FIG. 8 shows a third embodiment of the present invention.
FIG. 6 is an electric circuit diagram of a main part of a controller provided in the combustion control device according to the first embodiment, which is different from the circuit of the second embodiment shown in FIG. The point is that Q3 and resistors R7 and R8 are added. That is, the output end of the water amount sensor 14 is connected to the input end of the F / V conversion circuit 44 and the port 19i of the microcomputer 19, and the output end of the F / V conversion circuit 44 is connected to the transistor Q3 via the resistor R7. Connected to the base of. The collector of the transistor Q3 is connected to the connection point between the resistor R1 and the base of the transistor Q1, and the emitter of the transistor Q3 is grounded. The connection point between the output terminal of the F / V conversion circuit 44 and the resistor R7 is grounded via the resistor R8.

FIG. 9 is an electric circuit diagram of a main part of a water heater provided with a combustion control device according to the third embodiment of the present invention, and has the same configuration as the circuit of the second embodiment shown in FIG.

In the third embodiment, the water amount sensor 14
Is converted into a voltage by the F / V conversion circuit 44 and supplied to the base of the transistor Q3. That is, the water amount sensor 14 outputs a pulse signal having a frequency corresponding to the amount of water in the water channel 5, and the F / V conversion circuit 44 outputs a voltage inversely proportional to the frequency of the pulse signal from the water amount sensor 14. When the amount of water in the water channel 5 decreases, the frequency of the pulse signal from the water amount sensor 14 decreases, so that the output voltage of the F / V conversion circuit 44 increases, and the amount of water in the water channel 5 becomes a predetermined value as shown in (h) of FIG. When it becomes less than the value, the transistor Q3 is turned on. This lowers the base potential of the transistor Q1 and turns off the transistor Q1, so that the transistor Q2 is turned off by the same operation as that of the second embodiment, and the coil of the relay 41 is energized as shown in (g) of FIG. Then, the normally open contact 41a of the relay 41 is opened. Therefore, the connection between the AC power supply 36 and the rectifier 38 is cut off, the solenoids 6a, 7a, 8a of the solenoid valves 6, 7, 8 are no longer energized, and the solenoid valves 6, 7, 8 are closed. 10A shows the port 19 of the microcomputer 19.
voltage waveform of d, FIG. 10 (b) is on / off of the transistor Q1, FIG. 10 (c) is a current waveform flowing through the capacitor C1, and FIG. 10 (d) is a voltage waveform across the capacitor C2. 10E shows the on / off state of the transistor Q2, and FIG. 10F shows the voltage waveform of the port 19h of the microcomputer 19.

As described above, the transistor Q2 is turned off even when the amount of water in the water channel 5 drops below a predetermined value.
The solenoid valves 6, 7, 8 can be surely closed. Therefore, the fire can be reliably extinguished to prevent an abnormal supply of high-temperature water and damage to the heat exchanger 4, and the burner 2
It is possible to reliably prevent fuel leakage from the. Further, since the energization of the igniter 13 is also blocked, sparks for ignition do not occur. In addition, the switch means operation permitting means 21
Since the normally open contact 41a of the relay 41 is opened by
Even when the normally open contacts of the relays 22, 23, 24 are stuck and closed, the solenoid valves 6, 7, 8 can be reliably closed.

In the third embodiment, the relay 41 is controlled by the switch operation permitting means 21.
1 is not provided, and the port 19 of the microcomputer 19 is provided.
A pulse signal having a constant cycle is output from the e instead of the ON signal, and the switching means operation permitting means 2 is output to this port 19e.
1 may be connected and the relay 22 may be directly driven by the switch operation permitting means 21. Also,
It is also possible to provide two systems of the switch operation permitting means 21 and to use the control of the relay 41 and the control of the relay 22 together. Further, the relays 23 and 24 may also be configured to be controlled by the switch operation permitting means 21.

In the third embodiment, the normally open contact 41a of the relay 41 is provided on the input side of the rectifier 38, but the normally open contact 41a may be provided on the output side of the rectifier 38.

In the third embodiment, the transistor Q3 is turned on when the amount of water detected by the water amount sensor 14 becomes less than the predetermined value. However, a timer circuit is provided so that the amount of water detected by the water amount sensor 14 becomes a predetermined value. The transistor Q3 may be turned on when the state below is continued for a predetermined time or more.

(Embodiment 4) FIG. 11 is an electric circuit diagram of a main part of a controller provided in a combustion control apparatus according to Embodiment 4 of the present invention, which is different from the circuit of Embodiment 3 shown in FIG. The point is F in the switch means operation permitting means 21.
In place of the / V conversion circuit 44, a flame detection circuit 46 that detects a flame by a signal from the flame detector 9 and a flame detection circuit 46 that is activated by a signal from the port 19e of the microcomputer 19 and is timed up. The point is that a timer circuit 47 for supplying a signal to the base of the transistor Q3 is provided. That is, the output end of the flame detector 9 is connected to the input end of the flame detection circuit 46, and the output end of the flame detection circuit 46 is connected to the input end of the timer circuit 47 and the port 19j of the microcomputer 19. . The output terminal of the timer circuit 47 is connected to the transistor Q via the resistor R7.
The start control terminal of the timer circuit 47 is connected to the connection point between the port 19e of the microcomputer 19 and the base of the transistor 29.

FIG. 12 is an electric circuit diagram of a main part of a water heater equipped with a combustion control device according to a fourth embodiment of the present invention.
It has the same configuration as the circuit of the second embodiment shown in FIG. 6 and the circuit of the third embodiment shown in FIG.

In the fourth embodiment, the flame detection circuit 46 is used.
Outputs to the timer circuit 47 and the port 19j of the microcomputer 19 a signal according to the presence or absence of flame in the burner 2 based on the detection signal from the flame detector 9, and the timer circuit 47 causes the port of the microcomputer 19 to operate. The timing operation is started when the signal from 19e becomes high level, and after the time is up, the signal from the flame detection circuit 46 is supplied to the base of the transistor Q3. That is, when the burner 2 does not ignite or the flame of the burner 2 disappears, the detection signal output from the flame detector 9 becomes low level as shown in FIG. 13 (h), which causes the flame detection circuit 46. Output becomes high level. On the other hand, the timer circuit 47 starts a timing operation for a predetermined time from when the signal from the port 19e of the microcomputer 19 becomes high level, and outputs the output of the flame detection circuit 46 after the time is up. This is because there is no flame before the burner 2 is ignited, so that fuel can be supplied even during ignition. When the output of the timer circuit 47 becomes high level,
The transistor Q3 turns on. As a result, the base potential of the transistor Q1 drops and the transistor Q1 turns off.
Is turned off, the coil of the relay 41 is no longer energized as shown in FIG.
a opens. Therefore, the connection between the AC power supply 36 and the rectifier 38 is cut off, and the solenoid 6 of the solenoid valves 6, 7, 8 is
a, 7a, 8a are no longer energized, the solenoid valves 6, 7,
8 closes. 13A is a voltage waveform of the port 19d of the microcomputer 19, and FIG.
Is the on / off state of the transistor Q1, FIG. 13 (c) is the current waveform flowing through the capacitor C1, FIG. 13 (d) is the voltage waveform across the capacitor C2, and FIG. 13 (e) is the on / off state of the transistor Q2. Off, FIG. 13 (f) shows the voltage waveform of the port 19h of the microcomputer 19, respectively.

As described above, the transistor Q2 is turned off even if the burner 2 does not ignite or the flame once ignited disappears, so that the solenoid valves 6, 7, 8 can be surely closed. it can. Therefore, the fire can be surely extinguished, and the leakage of the fuel from the burner 2 can be surely prevented. Further, since the energization of the igniter 13 is also blocked, sparks for ignition do not occur. In addition, since the normally-open contact 41a of the relay 41 is opened by the switch-operation enabling means 21, even when the normally-open contacts of the relays 22, 23, and 24 are fixed in the closed state, the solenoid valve 6, is surely opened. The valves 7 and 8 can be closed.

Although the relay 41 is controlled by the switch operation permitting means 21 in the fourth embodiment, the relay 4
1 is not provided, and the port 19 of the microcomputer 19 is provided.
A pulse signal having a constant cycle is output as an ON signal from e, and the switch means operation permitting means 21 is output to this port 19e.
May be connected to drive the relay 22 directly by the switch operation permitting means 21. Further, two switching means operation permitting means 21 may be provided, and the control of the relay 41 and the control of the relay 22 may be used together. Further, the relays 23 and 24 may also be configured to be controlled by the switch operation permitting means 21.

In the fourth embodiment, the normally open contact 41a of the relay 41 is provided on the input side of the rectifier 38, but the normally open contact 41a may be provided on the output side of the rectifier 38.

[0041]

As described above, according to the invention of claim 1, the fuel valve can be opened by the solenoid valve only during the period when the pulse signal of a constant cycle is output from the microcomputer. Whether the output is held at a high level or a low level due to an abnormal operation of the microcomputer, the solenoid valve shuts off the fuel supply path in either case. However, it is possible to reliably extinguish the burner and stop the fuel supply to prevent fuel leakage.

According to the second aspect of the present invention, the fuel supply passage by the solenoid valve is provided only when the amount of water supplied to the heat exchanger is equal to or more than a predetermined amount and the pulse signal of a constant cycle is output from the microcomputer. Since it becomes possible to open
In addition to the effect of the invention of claim 1, since the burner can be surely extinguished even when the amount of water supplied to the heat exchanger does not reach the predetermined amount, the supply of high-temperature water and the overheating of the heat exchanger are excellent. Can be prevented.

According to the third aspect of the invention, the solenoid valve is present only during the period when the flame of the burner is present and the microcomputer outputs a pulse signal of a constant cycle except for a fixed time from the start of ignition. Since the fuel supply passage can be opened by means of the above, in addition to the effect of the invention of claim 1, the solenoid valve can surely shut off the fuel supply passage even if the ignition does not occur or the flame disappears after the ignition. Therefore, the fuel leakage can be effectively prevented.

[Brief description of drawings]

FIG. 1 is an electric circuit diagram of a main part of a controller included in a combustion control device according to a first embodiment of the present invention.

FIG. 2 is a schematic configuration diagram of a water heater including the combustion control device according to the first embodiment of the present invention.

FIG. 3 is an electric circuit diagram of a main part of a water heater including the combustion control device according to the first embodiment of the present invention.

FIG. 4 is a signal waveform diagram of each part of the controller provided in the combustion control device according to the first embodiment of the present invention.

FIG. 5 is an electric circuit diagram of a main part of a controller provided in a combustion control device according to a second embodiment of the present invention.

FIG. 6 is an electric circuit diagram of a main part of a water heater equipped with a combustion control device according to a second embodiment of the present invention.

FIG. 7 is a signal waveform diagram of each part of the controller provided in the combustion control device according to the second embodiment of the present invention.

FIG. 8 is an electric circuit diagram of a main part of a controller included in a combustion control device according to a third embodiment of the present invention.

FIG. 9 is an electric circuit diagram of a main part of a water heater provided with a combustion control device according to a third embodiment of the present invention.

FIG. 10 is a signal waveform diagram of each part of the controller provided in the combustion control device according to the third embodiment of the present invention.

FIG. 11 is an electric circuit diagram of a main part of a controller included in a combustion control device according to a fourth embodiment of the present invention.

FIG. 12 is an electric circuit diagram of a main part of a water heater including a combustion control device according to a fourth embodiment of the present invention.

FIG. 13 is a signal waveform diagram of each part of the controller provided in the combustion control device according to the fourth embodiment of the present invention.

[Explanation of symbols]

 2 burner 3 fuel supply path 6 solenoid valve 7 solenoid valve 8 solenoid valve 9 flame detector 14 water amount sensor 19 microcomputer 21 switch means operation permission means 22 relay 23 relay 24 relay 41 relay

Claims (3)

[Claims] 1. A combustion control device comprising: a solenoid valve for opening and closing a fuel supply passage; a switch means for controlling energization of the solenoid valve; and a microcomputer for controlling the switch means. Switch means operation permitting means for enabling the switch means to operate only when a pulse signal is input is provided, and the pulse signal of the constant cycle is based on a program stored in advance by the microcomputer. The combustion is characterized in that the fuel supply passage can be opened by the solenoid valve only during a period in which the pulse signal of the constant cycle is output by outputting the pulse signal to the switch means operation permission means. Control device. 2. A water amount sensor for detecting the amount of water supplied to a heat exchanger, a solenoid valve for opening and closing a fuel supply path, a switch means for controlling energization of this solenoid valve, and a micro controller for controlling this switch means. A switch for enabling the switch means to operate only when a water amount detected by the water amount sensor is a predetermined amount or more and a pulse signal of a constant cycle is input, the combustion control device including a computer. Means for permitting operation of the means, and outputting the pulse signal of the constant period to the means for permitting operation of the switch based on a program stored in advance by the microcomputer, whereby the amount of water supplied to the heat exchanger is determined. It is possible to open the fuel supply path by the solenoid valve only during a period when the pulse signal having a fixed period or more is output, which is equal to or more than the fixed amount. A combustion control device having a configuration. 3. A flame detector for detecting a flame of a burner, a solenoid valve for opening and closing a fuel supply passage, a switch means for controlling energization of the solenoid valve, and a microcomputer for controlling the switch means. A combustion control device,
Switch means operation permission that enables the switch means to operate only when the flame detector detects a flame and a pulse signal of a constant cycle is input except for a fixed time from the start of ignition. Means for outputting the pulse signal of the constant cycle to the switch means operation permitting means based on a program stored in advance by the microcomputer, so that the flame of the burner is extinguished except for a fixed time from the start of ignition. A combustion control device, characterized in that the fuel supply passage can be opened by the solenoid valve only during a period in which the pulse signal is present and the constant-cycle pulse signal is being output.