JPH09243066A - Gas valve driver for gas combustor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a gas valve driver having a protecting mechanism for ensuring to obtain the safety of an apparatus by forcibly fixing the drive signal of a transistor included in a driving circuit during stopping of a combustor. SOLUTION: This gas valve driver for a gas combustor comprises transistors Q1 , Q2 for driving gas solenoid valves 11, 12, a driving circuit 31 having a transistor Q3 which operates when a pulse signal DS3 is inputted to make it possible to operate the transistors Q1 , Q2 , and a microcomputer M1 for generating the signal DS3 . The pulse DS3 is stopped at the time of stopping an apparatus. With such a constitution, since the circuit 31 maintains OFF during stopping to make the transistors Q1 , Q2 impossible to operate, even if a fault occurs in the circuit during the stopping, the openings of the valves 11, 12 are prevented to ensure the safety of the apparatus.

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 or a gas stove, and more particularly to drive control of a gas solenoid valve for supplying / stopping combustion gas. It is a thing.

[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. 4 shows an example of a circuit of a gas valve drive device for controlling the opening and closing of the gas solenoid valve.

The drive unit in FIG. 4 is a gas solenoid valve 11,
12 and transistors Q1 and Q2 for independently driving the gas solenoid valves 11 and 12, diodes D5 and D6,
A switch circuit 30 composed of resistors R5 and R4, and a drive circuit 31 for collectively driving these transistors Q1 and Q2 with a transistor Q3 are provided.
The drive signals DS1, DS2, DS3 of Q2, Q3 are output from a microcomputer (hereinafter simply referred to as a microcomputer) M1 as a control device for controlling the operation of loads (for example, the gas solenoid valves 11, 12). Also, each transistor Q
The drive output signals of 1 and Q2 are input to a single input port AN of the microcomputer M1 as a single energization sense signal SNS through one signal line, and the operation of the transistors Q1, Q2 and Q3 and the gas solenoid valves 11 and 12 is performed. It is used for checking.

By the way, the drive signal DS3 is a pulse signal of a predetermined cycle, and as long as the operation of the microcomputer M1 is normal, it is always output from the output port WDT of the microcomputer M1 as proof that it is normal.

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 of the transistor Q3 operable even when the combustion equipment is stopped, and the pulse signal DS3 is stopped ( For example, the transistor Q3 remains on until the microcomputer runs away and the program does not operate normally and the output of the output port WDT is fixed.

On the other hand, the drive signals DS1 and DS2 of the transistors Q1 and Q2 are level signals output to the output ports SV1 and SV2 at the start of the combustion operation of the equipment, and when the transistor Q3 is in the ON state, the drive signals D
By turning on / off the transistors Q1 and Q2 corresponding to S1 and 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.

[0010]

However, with the configuration in which the pulse signal DS3 is always output as described above, when the transistors Q1 and Q2 are illegally turned on for some reason, the operation is stopped. Despite this, the gas solenoid valves 11 and 12 may open.

An object of the present invention is to solve the above problems and to provide a gas valve drive device which further secures the safety of the equipment by forcibly fixing the drive signal DS3 of the transistor Q3 while the combustor is stopped. Is to provide.

[0012]

That is, according to the present invention, a circuit for driving a gas solenoid valve, and a drive circuit that operates when a periodic pulse signal is input to enable the circuit to operate,
In a gas valve drive device of a gas combustor including a microcomputer having a signal generating unit for generating the pulse signal, the microcomputer stops the pulse signal when the gas combustor is stopped. Characterize.

[0013]

1 is a diagram showing an internal structure of a gas fan heater as a representative of a gas warm air heater to which the present invention is applied, in which (a) is a front view and (b) is a side view. is there. Further, FIG. 2 is a block configuration diagram thereof.

First, the structure of the gas fan heater will be described with reference to FIG. 1. Reference numeral 1 is an outer case, and an air inlet 3 having an air filter 2 and an air cleaner attached to the upper rear portion, and a front portion. A warm air outlet 4 is provided in the lower portion, and an operation panel 5 is provided in the upper surface portion. Further, a combustion chamber 8 provided with an ignition plug 7 as an ignition device and a main burner 6 as a burner is provided above the inside of the outer case 1 and for combustion air supply and convection in the vicinity of a warm air outlet 4 further below. Sirocco fan 1 as a blower that doubles as a fan
9 are provided.

A gas injection nozzle 9 whose front end is faced is arranged near the inlet of the member 6 and a proportional gas valve 10 for adjusting the gas supply amount and the supply and stop of the fuel gas are provided by the nozzle 9. A gas solenoid valve 11 (which is disposed on the back side of the gas solenoid valve 12 in the figure) for performing the gas provided in the lower rear portion of the outer case 1 by a gas pipeline (not shown) in which 12 is connected. It is connected to the plug 13.

Further, an overheat prevention thermistor 14 for preventing overheating of the gas combustor, an overheat prevention temperature fuse 15, a thermocouple 16 for detecting a flame state 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, an 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 member 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 as a combustion gas in the combustion chamber 8 where it is warmed up. The air in the combustion chamber 8 becomes hot air and is blown out of the equipment from the hot air outlet 4 by the fan 19.

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.
A drive device for a gas solenoid valve mounted on the electrical component unit 18, the circuit configuration of which is the same as that of FIG. 4 already described,
The generation timing of the pulse signal DS3 output from the output port WDT of the microcomputer M1 for controlling the operation of the load (for example, the gas solenoid valves 11 and 12, the fan 19 and the like) is different from the conventional timing.

That is, in the past, the pulse signal DS3 was always generated while the operation of the equipment was stopped as long as the microcomputer M1 was operating normally. However, in the case of the present invention, the pulse signal DS3 is generated only during the combustion operation. It is something that is generated.

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 equipment 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 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 the operation start mode is determined by the determination in step 22, 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 having 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 In addition, when this program processing is in an unexecutable state due to a runaway of the microcomputer M1 or when it is on during combustion.
The same applies when the OFF operation is OFF.

As described above, if the generation of the pulse signal DS3 is stopped while the operation of the equipment is stopped, even if the transistors Q1 and Q2 are illegally turned on due to a failure of the drive circuit or the like during that time, the pulse signal DS3 is already turned on. Since the transistor Q3 for driving these is off, there is no concern that the gas solenoid valves 11 and 12 will be energized.

[0029]

As described above, according to the present invention,
Since the input pulse signal to the drive circuit is stopped when the operation of the gas combustor is stopped, the drive circuit maintains the OFF state during this period to disable the circuit for driving the gas solenoid valve. Even if a failure occurs, the gas solenoid valve does not open, which further improves the safety and reliability of the gas combustor.

[Brief description of drawings]

FIG. 1 is a diagram showing an internal structure of a gas fan heater as a gas combustor to which the present invention is applied, in which (a) is a front perspective view,
(b) is a side perspective view.

FIG. 2 is a block diagram of a gas fan heater as a gas combustor.

FIG. 3 is a flowchart of the operation of the gas valve drive device of the same.

FIG. 4 is a circuit diagram of a gas valve driving device of a gas fan heater.

[Explanation of symbols]

 11, 12 Gas solenoid valve 30 Circuit for driving gas solenoid valve 31 Drive circuit DS3 pulse signal M1 microcomputer

Claims (1)

[Claims] 1. A circuit for driving a gas solenoid valve, a drive circuit that operates when a periodic pulse signal is input and enables the circuit, and a signal generator for generating the pulse signal. A gas valve driving device for a gas combustor, comprising: a microcomputer provided with the microcomputer, wherein the microcomputer stops the pulse signal when the operation of the gas combustor is stopped.