JPH09310848A - Safety device of gas burning appliance - Google Patents

Abstract

PROBLEM TO BE SOLVED: To fix a solenoid valve on the closing operation side forcibly and thereby to further ensure the safety of a gas burning appliance by a system wherein a control means stops a periodic signal at the time of stoppage of operation of the appliance. SOLUTION: A second safety circuit 32 is added. In a state wherein a power switch SW is ON, a transistor Q4 is turned OFF forcibly and, therefore, an operation of a first safety circuit 31 is given priority. In a state wherein the power switch SW is OFF, the transistor Q4 is turned ON forcibly and, therefore, a transistor Q3 of the first safety circuit 31 is turned OFF forcibly irrespective of an output of an output port WDT of a microcomputer M1. In the state of the power switch SW being OFF, therefore, a solenoid valve drive circuit 30 is turned OFF and gas solenoid valves 11 and 12 are not electrified. Since the gas solenoid drive circuit is held in the OFF state and the circuit for driving the gas solenoid valves is inhibited from operating, in this way, the gas solenoid valves do not conduct opening operations even when a failure occurs in the gas solenoid valve drive circuit, and thus the safety and reliability of a gas burning appliance can be further improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas heater represented by a gas hot air heater such as a gas fan heater and a gas stove, and more particularly to safely driving a gas solenoid valve for supplying / stopping combustion gas. The present invention relates to a safety device for a gas combustor to be controlled.

[0002]

2. Description of the Related Art Generally, in a gas combustor of this type, two gas solenoid valves and one gas proportional valve are connected in series in a gas pipeline for guiding combustion gas from a gas plug to a main burner. First, the gas solenoid valve simply opens and closes the valve part to supply / stop the fuel gas, and the gas proportional valve changes the opening of the valve part by changing the current to supply the amount of gas supplied to the main burner. Adjust.

Originally, in the equipment accompanied with such combustion,
From the aspect of ensuring safety against fire accidents, etc., not only the gas proportional valve that adjusts the amount of gas that can be a factor but also the gas solenoid valve that controls the supply of fuel gas, the drive unit has a safety mechanism in the event of an abnormality. Is equipped with.

FIG. 6 shows an example of a circuit of a gas solenoid valve drive device for controlling the opening / closing of the gas solenoid valve. The drive device in FIG. 6 includes gas solenoid valves 11 and 12 and diodes D5 and D6.
And a switch circuit 30 as a solenoid valve drive circuit composed of transistors Q1 and Q2 and resistors R5 and R4 for independently driving these gas solenoid valves 11 and 12, and transistors Q1 and Q2 of the solenoid valve drive circuit 30. It is composed of a safety circuit 31 as a first safety circuit including a transistor Q3 to be collectively driven, and a control means M1 for controlling the switch circuit 30 and the safety circuit 31.

The drive signals DS1, DS2, DS3 for driving the respective transistors Q1, Q2, Q3 are described above for controlling the operation of the load (for example, the gas solenoid valves 11, 12 or a gas proportional valve and a blower not shown). The signals are output from the first signal generating section SV1, the second signal generating section SV2, and the third signal output section WDT, which are included in a microcomputer (hereinafter simply referred to as a microcomputer) M1 as a control means.

The drive output signals of the transistors Q1 and Q2 are input to a single input port AN of the microcomputer M1 as a single energization detection signal SNS by a single signal line.
Transistors Q1, Q2, Q3 and gas solenoid valves 11, 1
It is used for the operation check of item 2.

By the way, in the normal state, the drive signal DS3 for driving the safety circuit 31 is a periodic pulse generated at a predetermined cycle when the power switch for instructing the start and stop of the operation of the gas combustor is turned on. As long as the operation of the microcomputer M1 is normal, the signal is always output from the output port WDT, which is the third signal generator of the microcomputer M1, as proof that the microcomputer itself is normal. In an abnormal state (for example, the microcomputer has runaway and the program has stopped operating normally), this output port WDT
Output is fixed to high level H or low level L.

This pulse signal DS3 is output to the output port WDT.
It is differentiated by the capacitor C1 connected to the capacitor C1 and the differentiated voltage is charged in the capacitor C2 via the diode D2. When the charging voltage rises and the base potential of the transistor Q3 rises above the threshold level via the resistor R2, it is turned on. Therefore, the transistor Q3 is turned on by the pulse signal DS3 to make the transistors Q1 and Q2 connected to the collector side thereof operable even when the combustion device is not in operation until the pulse signal DS3 is stopped. The transistor Q3 remains on.

On the other hand, the drive signals DS1 and DS2 of the transistors Q1 and Q2 are level signals output from the output ports SV1 and SV2 as the first signal generating section and the second signal generating section at the start of the combustion operation of the equipment, When the above-mentioned transistor Q3 is in the ON state, this drive signal DS1,
By turning on / off the transistors Q1 and Q2 corresponding to DS2, the corresponding gas solenoid valves 11 and 12 can be driven, that is, the opening and closing operations of the valves can be performed.

With such a circuit configuration, fuel gas supply /
Transistors Q1 and Q2 for individually driving the two gas solenoid valves 11 and 12 provided with a stop in series, and a transistor Q3 capable of driving these transistors Q1 and Q2
It is triple protected and safe.

[0011]

However, when the pulse signal DS3 is always output as described above, when the transistors Q1 and Q2 are illegally turned on for some reason, for example, a disturbance (noise) is generated. Signal), the gas solenoid valve 11, despite the fact that the operation is stopped during on / off operation control as a gas combustor, such as turning on the solenoid valve,
There was a possibility that 12 would remain open.

An object of the present invention is to solve the above problems and to forcibly fix the drive signal DS3 of the transistor Q3 to the safety side, that is, the closing operation side of the solenoid valve while the combustor is stopped.
It is an object of the present invention to provide a safety device for a gas combustor that makes the safety of the device more reliable.

[0013]

That is, according to the first aspect of the invention, a solenoid valve drive circuit for individually driving a plurality of gas solenoid valves, and a first operation control for the drive circuits collectively.
A safety circuit, a drive signal generator that controls the operation of the drive circuit based on the operating state of the power switch and the temperature detected in the heated chamber, and a cycle that controls the operation of the first safety circuit based on the operating state of the power switch. In a gas combustor provided with a control means having a signal generator, the control means,
A safety device for a gas combustor for stopping the periodic signal when the operation of the gas combustor is stopped.

Further, according to the invention of claim 2, an electromagnetic valve drive circuit for individually driving a plurality of gas solenoid valves, a first safety circuit for collectively controlling the operation of the drive circuits, and an operating state of a power switch. And a control means having a drive signal generator that controls the operation of the drive circuit based on the temperature detected in the heated chamber, and a periodic signal generator that controls the operation of the first safety circuit based on the operating state of the power switch. A gas combustor provided with a second safety circuit for forcibly stopping the drive circuit when the power switch is turned off.

Further, in the invention of claim 3, in addition to the configuration of claim 2, the control means has a switch signal determination section for inputting a switch signal corresponding to an on / off state of the power switch.

[0016]

1 is a front view showing the internal structure of a gas fan heater representing a gas warm air heater in a gas combustor to which the present invention is applied, and FIG. 2 is a side view thereof.
3 is a block diagram of a control device for controlling the operation of the gas fan heater, FIG. 4 is a flow chart showing an embodiment of a control means having a signal generator for generating a periodic pulse signal, and FIG. It is a circuit diagram which shows one Example of the safety device of a fan heater.

First, the structure of the gas fan heater will be described with reference to FIG. An outer case 1 is provided with an air inlet 3 having an air filter 2 and an air cleaner attached on the upper back side, and a warm air outlet 4 on the lower front side, and an operation panel 5 on the upper side. It is arranged. Further, a combustion chamber 8 having a spark plug 7 as an ignition device and a main burner 6 as a burner is provided above the outer case 1, and in the vicinity of a warm air outlet 4 further below, there is a convection for supplying combustion air. Sirocco fan 1 as a blower that also serves as a fan
9 are provided.

A gas injection nozzle 9 is disposed near the inlet of the main burner 6 with its tip facing.
The nozzle 9 is provided with a gas proportional valve 10 for adjusting the gas supply amount, and a gas solenoid valve 11 (which is arranged behind the gas solenoid valve 12 in the figure) 12 for supplying and stopping the fuel gas. It is connected to a gas plug 13 provided at the lower part of the back surface of the outer case 1 by a gas pipeline (not shown).

Further, an overheat prevention thermistor 14 for preventing overheating of the gas combustor, an overheat prevention temperature fuse 15, and a thermocouple 16 for detecting the state of flame and abnormal combustion, etc., are respectively provided in the outer case 1. A room temperature thermistor 1 for detecting room temperature, which is installed at a position to prevent abnormal overheating and abnormal combustion during combustion operation, and is also hard to be directly affected by hot air.
7 is attached. Further, on the right side surface, an electric component unit 18 having a control device for controlling the operation of the combustor is mounted.

Next, the outline of the operation of combustion control and hot air generation will be described based on the block diagram of FIG. First, the operation panel 5
When the combustion operation of the equipment is started by operating, the gas solenoid valve 11 and the gas solenoid valve 12 are opened, and the fuel gas is supplied through the gas plug 13. The fuel gas that has passed through each of the gas solenoid valves is adjusted in gas supply amount by the gas proportional valve 10, and is injected from the tip portion of the nozzle 9 to the main burner 6. The injected fuel gas is mixed with the combustion air flowing in from the air suction port 3 to form a mixed gas, which is ignited by the ignition plug 7 and rises in the combustion chamber 8 as a combustion gas.
The air in the combustion chamber 8 heated here becomes hot air and is blown out of the device by the fan 19 from the hot air outlet 4.

At this time, based on the room temperature detected by the room temperature thermistor 17 and the set temperature set by the operation panel 5, the opening of the gas proportional valve 10 and the rotation speed of the fan 19 are adjusted by the microcomputer M1 to be described later. The combustion amount (that is, the gas amount and the air amount) is controlled to maintain the temperature at the set temperature. During the combustion operation, the overheat prevention thermistor 14, the overheat prevention temperature fuse 15, the thermocouple 16, etc. ensure the closing operation of the gas solenoid valves 11 and 12 even when abnormal overheat and abnormal combustion occur, thus ensuring the safety of the equipment. Has been planned.

The features of the present invention are as follows.
This is a safety device for the gas solenoid valve mounted on the electrical unit 18. The circuit configuration is the same as that shown in FIG. 6 described in the related art, but a microcomputer (hereinafter simply referred to as a microcomputer) as a control means for controlling the operation of the load (for example, the gas solenoid valves 11, 12 and the fan 19). The generation timing of the pulse signal DS3 output from the output port WDT as the third signal generation unit of M1 is different from the conventional timing.

That is, conventionally, if the pulse signal DS3 is applied to the power source as long as the microcomputer M1 is normally operating, the device is always stopped (that is, stopped in the on / off operation control). However, in the case of the present invention, the pulse signal DS3 is generated only during the combustion operation.

Explaining the concrete structure, the second structure in FIG.
The safety circuit 32 is added. Second safety circuit 32
Is a transistor Q4 whose collector is connected to the base (see connection point S2) of the transistor Q3 of the first safety circuit 31, resistors R6 and R7 connected in series between the DC power supply VDD and the base of the transistor Q4, and both resistors. Connection point S1
And a lock-type power switch SW connected to.
One end of the power switch SW is installed. Further, at the connection point S1, the operating state of the power switch SW (that is, on / off)
The switch signal determination unit AN2 of the microcomputer M1 for inputting the switch signal corresponding to is connected.

According to the second safety circuit 32 of FIG. 5, the transistor Q4 is forcibly turned off when the power switch SW is on, that is, when the connection point S1 is grounded. Is prioritized. Also,
Since the transistor Q4 is forcibly turned on when the power switch SW is off, that is, when the potential of the connection point S1 is the division potential, the transistor Q4 of the first safety circuit 31 is turned on.
3 forcibly turns off regardless of the output of the output port WDT of the microcomputer M1. Therefore, the power switch SW
The solenoid valve drive circuit 30 is turned off during the OFF period of the above, and the gas solenoid valves 11 and 12 are not energized.

In any case, since the microcomputer M1 is monitoring the on / off state of the power switch SW through the switch signal judging section AN2, the microcomputer M1 is utilized for controlling the operation of the microcomputer such as the following flow charts.

On the other hand, an embodiment of the microcomputer M1 for generating the pulse signal DS3 will be described below with reference to the flowchart of FIG.

First, in step 20, an abnormality of the device is checked, and if it is in an abnormal state, no program processing is executed. In the present embodiment, it is assumed that a program configuration is adopted in which the abnormality detection of the device is performed by another program process and the abnormality flag set at that time is checked by this process.

If the equipment is judged to be normal by the above-mentioned abnormality check in step 20, step 21 is executed to check the operation of the operation switch (for example, the tact switch of the operation panel 5). At this time, if the operation switch is turned on, the operation start mode is checked in step 22, and if it is not the operation start mode, the operation is started, and in the next steps 23 and 24, the operation start mode and the pulse output mode are changed. It is set, and then step 27 is executed.

On the other hand, if it is determined in step 22 that the mode is the operation start mode, the operation start mode and the pulse output mode are reset, and then step 27 is executed.

In step 27, the pulse output mode is checked, and if the device is in the pulse output mode, step 2
At 8, the port output (WDT output port) is inverted, and this processing ends.

On the other hand, if the pulse output mode is reset in the determination at step 27, the port output operation is not executed and the processing directly ends. The series of processes is configured to occur periodically by an interval timer or the like.

As described above, since the port output periodically generated by the microcomputer M1 is repeatedly inverted, the pulse signal DS3 of a predetermined cycle is output from the output port WDT of the microcomputer M1 during the operation of the equipment. Further, if the operation switch is operated again and the operation is stopped, the inversion processing of the port output is not executed and the pulse signal DS3 is maintained at either the "H" level or the "L" level. It Also, when this program processing becomes inexecutable due to runaway of the microcomputer M1 or when it is burning
-OFF The same is true during OFF of the operation.

As described above, since the generation of the pulse signal DS3 is stopped while the operation of the equipment is stopped, the transistors Q1 and Q2 are illegally operated during that time due to the failure of the gas solenoid valve drive circuit 30 or the like. Even if it is turned on, the transistor Q3 for collectively driving and controlling them is turned off, so that there is no concern that the gas solenoid valves 11 and 12 are energized.

Further, according to the second safety circuit 32, when the power switch SW is on, the transistor Q4 is forcibly turned off. Therefore, the operation of the first safety circuit 31 is prioritized and the power switch SW is off. In the state, since the transistor Q4 is forcibly turned on, the first safety circuit 31
Transistor Q3 is output port WDT of microcomputer M1
Is forcibly turned off regardless of the output of. Therefore, while the power switch SW is off, the solenoid valve drive circuit 30 is off and the gas solenoid valves 11 and 12 are not energized. This is the same when the program processing becomes inexecutable due to a runaway of the microcomputer M1 or when the ON-OFF operation during combustion is OFF.

[0036]

As described above, according to the invention of claim 1, the periodic pulse signal to the gas solenoid valve drive circuit is stopped when the operation of the gas combustor is stopped.
During this period, the gas solenoid valve drive circuit is maintained in the off state, and the circuit that drives the gas solenoid valve becomes inoperable, so even if this gas solenoid valve drive circuit fails, the gas solenoid valve does not open, Therefore, the safety and reliability of the gas combustor is further improved.

According to the second aspect of the present invention, when the power switch is on, the second safety circuit is forcibly turned off to give priority to the operation of the first safety circuit, and when the power switch is off. , Is forcibly turned on and the first safety circuit is forcibly turned off regardless of the output of the signal generator of the control means. Therefore, while the power switch is off, the gas solenoid valve drive circuit is turned off, the gas solenoid valve is not energized, and the safety of the gas combustor is further enhanced. This is the same when the program processing is in an unexecutable state due to a runaway of the control means or when the on / off operation during combustion is off.

Further, according to the third aspect of the invention, since the on / off state of the power switch is constantly monitored by the switch signal judging section, the switch signal can be utilized in another program, and the failure of the switch can be detected.

[Brief description of drawings]

FIG. 1 is a front perspective view showing an internal structure of a gas fan heater as a gas combustor to which the present invention is applied.

FIG. 2 is a side perspective view of the same gas fan heater.

FIG. 3 is a block diagram of a control device for the gas fan heater.

FIG. 4 is an operation flowchart of the control device for the gas fan heater.

FIG. 5 is a circuit diagram showing an example of a safety device for the gas fan heater.

FIG. 6 is a circuit diagram showing a conventional technique of a gas valve driving device of a gas fan heater.

[Explanation of symbols]

 11, 12 Gas solenoid valve 30 Gas solenoid valve drive circuit 31 First safety circuit 32 Second safety circuit DS3 Periodic pulse signal M1 Control means (microcomputer) SW power switch

Claims (3)

[Claims] 1. A solenoid valve drive circuit for independently driving a plurality of gas solenoid valves, a first safety circuit for collectively controlling the operation of the drive circuits, an operating state of a power switch, and a detected temperature of a heated chamber. A drive signal generator that controls the operation of the drive circuit based on the above, and a control unit that has a periodic signal generator that controls the operation of the first safety circuit based on the operating state of a power switch, The safety device for a gas combustor, wherein the control means stops the periodic signal when the operation of the gas combustor is stopped. 2. A solenoid valve drive circuit for independently driving a plurality of gas solenoid valves, a first safety circuit for collectively controlling the operation of the drive circuits, an operating state of a power switch, and a detected temperature of a heated chamber. A drive signal generator that controls the operation of the drive circuit based on the above, and a control unit that has a periodic signal generator that controls the operation of the first safety circuit based on the operating state of a power switch, A safety device for a gas combustor, comprising a second safety circuit for forcibly stopping the drive circuit when the power switch is turned off. 3. The safety device for a gas combustor according to claim 2, wherein the control unit has a switch signal determination unit for inputting a switch signal corresponding to an on / off state of the power switch.