JPS63123923A - Safety control device for burner - Google Patents

Abstract

PURPOSE:To improve reliability, by a method wherein, in a title device employing a microcomputer, a plurality of check points are situated in a microcomputer program, an output signal from the check point is monitored by means of a monitoring circuit, and property of combustion is decided. CONSTITUTION:On-off signals from an operation switch 11 and a stop switch 12 are inputted to input ports 7-1 and 7-2 of a microcomputer 7, a signal from a reset circuit 9 to an input port 7-3, and a detecting signal from a flame detecting circuit 8 to an input port 7-4. The microcomputer 7 inputs a high or a low signal to a monitoring circuit 10 according to situation in relation to each of the input signals. The monitoring circuit 10 decides that a combustion state is normal when an inputting signal in a continuous pulse signal and it is abnormal when a discontinuous pulse signal. When abnormal, a reset signal is outputted to a reset terminal 7-3. This constitution enables improvement of reliability.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a safety control device for a combustor that uses a microcomputer to control fuel supply and check for runaway of the microcomputer. .

Conventional technology In a conventional combustor safety control system using a microcomputer, the microcomputer determines the presence or absence of a flame based on the signal from the flame detection circuit and controls the fuel supply. A checkpoint was installed inside the device, a pulse was generated at the checkpoint, the presence or absence of the pulse was determined by a visual circuit, and the microcomputer was reset.

Problems that the invention aims to solve Microcomputer programs have only one checkpoint, and when they pass a checkpoint (pass through a regular routine), they enter the cancer vision circuit.

It only outputs pulse output.

Therefore, the microcomputer may go out of control and output pulses to the visual circuit without going through the regular routine. At this time, the visual circuit receives pulse output from the microcomputer, so it determines that it is normal, and does not allow the microcomputer to continue operating, even if something is wrong with the combustor.

Measures to solve the problem If you set multiple checkpoints in the microcomputer program and execute the program that the microcomputer is likely to miss (
(if passed through regular routines).

When the checkpoint is passed, the control circuit outputs a negative or low level to the main circuit (instead of outputting a pulse output), and the control circuit does not output a pulse when the input is a continuous pulse, but outputs a continuous Outputs a reset pulse for the microcomputer at times other than normal.

If the operating microcomputer is passing through a regular routine, it outputs rHj and rLJ to the cancer parent circuit at each checkpoint. Therefore, the cancer parent circuit determines that the microcomputer is normal,
Allow the microcomputer to continue operating. The check output of the microcomputer is not a pulse, but rHj, rLJ (i.e.)
・Since it was at a low level, the checkpoint could not be passed due to the microcomputer going out of control.

Whether the check output is high or low.

The microcomputer's main circuit is determined to be abnormal and the microcomputer is reset.

Example· An embodiment of the present invention will be described below with reference to the drawings.

In Fig. 1, 1 is an AC power source, and 2 is an igniter.

3 is a blower motor (BM), 4 is a burner (not shown)
This is a solenoid valve (SV) that controls the supply and stop of fuel.

5 is a DC power supply that converts alternating current into direct current, and serves as a power source for a microcomputer, etc. 7 is a microcomputer, 8 is a flame detection circuit such as a flame rond method, and when it detects the presence of flame from input 8-1, output 8-2 is the level, and when there is no flame, it outputs 8-2. Outputs at a lower level. 9 outputs a high level from the output 9-2 when the DC power supply detects a voltage lower than the specified voltage from the input 9-1 when the power is turned on, and outputs a low level after a certain period of time has passed since the voltage reaches the specified voltage. This is a reset circuit that outputs. 10 is the main circuit of the microcomputer 7. When continuous pulses are input from the input 10-1, a low level is output from the output 10-2, and when the pulse is interrupted, the signal from the input 10-1 is high. Alternatively, in the case of a constant low-level input, output 10-2 outputs a Gino-I level. 11 is an operation switch, 12 is a stop switch, and a signal is input from the input port 1.7-2 of the microcomputer 7 through load resistors 13 and 14. Reference numeral 15 denotes an OR gate which receives the output 9-2 of the reset circuit 9 and the output 10-2 of the parent circuit 10, and receives a signal from the input port 5 (reset terminal) of the microcomputer 7. Microcomputer 7
The input port 4 is a port for inputting the output 8-2 of the flame detection circuit 8. Output port 5.7-6, 7-7
is the igniter 2. This is an output port that drives the coils of relays 16, 17, and 18 that control the blower motor 6 and the solenoid valve 4. The output port 8 is an output port that outputs continuous pulses when the microcomputer is operating through a normal routine. In order to correspond h with the flowchart, it is made to correspond with the symbol WT. The flowchart shown in FIG. 2 is added to the basic program of the microcomputer 7.

The present invention consists of the above configuration.

When the AC power is turned on first, the DC power starts up.

A signal is input to the input 9-1 of the reset circuit 9 and the voltage reaches a specified level, and after a certain period of time, a pulse is output from the output 9-2. This signal passes through the OR gate 15 and enters the reset terminal 7-6 of the microcomputer.

By resetting the microcomputer 7, it enters the reset state and starts operation. Note that the output is turned off during reset. Microcomputer 7 is connected to input port 1.7-2 and operation switch 1.
1. Looking at the stop switch 12, if there is no signal, the stop switch 12 is not on, so w'r=H, that is, the output port 8 becomes high level. Next, process 2 (combustor general control means) is performed. Next, look at the output 8-2 from the input port 4, and check the input 8-1 of the flame detection circuit 8.
If there is no flame, the output 8-2 is at a low level, so the microcomputer determines that there is no flame and turns off 5V (18, 4).

That is, the output port 7 of the microcomputer 7 is off, no current flows through the relay coil 18, its contact 18 is open, the solenoid valve 4 is open, and the fuel is cut off. When the operation switch 11 is pressed here, a high level signal is input to the input port 2 of the microcomputer 7, so the output port 5.7-6°7-7 of the microcomputer 7 is turned on, and the relay coil 16, 17, 18 is turned on. Contacts that carry current are closed 1. Igniter 2. The blower motor 3 and solenoid valve 4 are turned on and 2 ignition starts. Yes - After a certain period of time, the output port of microcomputer 7 is
is off.

No current flows through the relay coil 16, the contacts are opened, the two igniters 2 are turned off, and steady combustion occurs.

Next, the flowchart shown in FIG. 2 will be explained.

During steady combustion, the stop switch 12 is not turned on, so a loop of 0 occurs, and w'r=H, that is, the output port 8 becomes a high level. Next, process 2 is performed. Next, when looking at the output 8-2 from the input port 4, there is a flame at the input 8-1 of the flame detection circuit 8, so the output 8-2 is at a high level, and the microcomputer determines that there is a flame and 5V (18,4 ) is turned on■.

That is, the output port 7 of the microcomputer is turned on, current continues to flow through the relay coil 18, and the relay contact 18-2 remains closed.

The solenoid valve 4 is closed and combustion continues.

At this point, the microcomputer 7 went out of control due to noise etc.

If only the routine ■ in the flowchart passed,
WT=H, that is, since only a high level signal is output from the output port 8, the input 10-IK of the main circuit 10 receives only a high level signal, so the output 10-2 becomes high level, and the OR gate 15, a high level signal is input to the reset terminal 7-3, and the microcomputer 7
will be reset.

At that point, the output is turned off, so the relay coil 16°17
, 18, no current flows and the contacts are open.

Igniter 2. Combustion blower motor 3. The solenoid valve 4 is turned off and stops operating, the fuel is cut off, and the operation is performed on the safe side.

Next, a case will be explained in which the microcomputer goes out of control and only the flow chart (■) is passed. In this case, WT=L
That is, since only a low level signal is output from the output port 8, only a low level signal comes to the input 10-1 of the main circuit 10, so the output 10-2 becomes high level.

Then, the microcomputer 7 is reset and the fuel is cut off.

If the microcomputer goes out of control and neither 0 nor ■ in the flowchart passes, WT=L or H.

The input 10-1 of the main circuit 10 receives only low or high level signals, and the output 10-2 becomes high level.

The microcomputer 7 is reset and fuel is cut off.

Effects of the Invention As described above, the present invention provides a plurality of checkpoints in a microcomputer program, outputs a high or low level each time the checkpoint is passed, and causes the signal to be viewed by a parent circuit.

If the signal to the main circuit is a continuous pulse signal, the main circuit determines that it is normal, and if it is not, it sends a reset signal to the microcontroller as an abnormality.

There is an advantage that the reliability of the device is higher than that of the conventional device.

[Brief explanation of the drawing]

FIG. 1 is a wiring diagram showing a safety control device for a combustor according to an embodiment of the present invention, and FIG. 2 is a flowchart of a program of the microcomputer. 7... Microcomputer, 10... Main circuit 7-3...
Reset terminal.

Claims (1)

[Claims] In the combustor safety control system, which controls the solenoid valve that supplies fuel to the burner with the output of the microcomputer and checks for runaway of the microcomputer via the visual circuit, multiple check points are set in the program of the microcomputer (7). In addition, a means for outputting a high or low signal is provided for each check point, and a viewing circuit (10) which receives the signal as input is provided, and the output of the viewing circuit (10) is sent to the microcomputer (7). Connect to the reset terminal (7-3), and if the input to the vision circuit (10) is a continuous pulse, the reset pulse of the microcomputer will not be output, and if the input to the vision circuit (10) is a continuous pulse, it will not be output. In this case, the reset terminal (7-) of the microcontroller (7)
3) A combustor safety control device characterized by outputting a reset pulse to.