JPS6099930A - Combustion control device - Google Patents

Abstract

PURPOSE:To permit to protect the whole of a system from stopping into unsafe direction with respect to a partial defect except the perfect stop due to runaway of a microcomputer by a method wherein a final safety circuit, operating regardless of the operation of the microcomputer upon runaway of the microcomputer like as a hardware, is provided in the device. CONSTITUTION:When the microcomputer 24 is broken under a condition that P1 port is fixed at ''H'' by some reason such as static electricity or the like, the coil of a relay 18 is excited, a contact 18a is closed and a heater 7 is left conducted. When the temperature of an evaporating cylinder is increased abnormally to a temperature immediately before the melting of the cylinder, a burner thermystor 22 detects the abnormality and a loop is changed to the loop 44 by an abnormality detecting routine 43. Then, a processor 45 outputs a signal to make P1 port -P4 port ''L'' and, thereafter, the processor 46 makes the P0 port ''H''. When a signal wire 35 becomes ''H'', a transistor 37 is put ON, the potential of a connecting point between a capacitor 39 and a resistor 38 is fixed to Ov and F/v converting circuit 26 is stopped, therefore, the transistor 27 is also put OFF, the transistor 19 is also put OFF and the supply of electricity for a bus bar is stopped. Thereafter, conduction of the coil of the relay 18 is stopped even if the signal wire is kept in ''H'', therefore, the contact 18a is opened and the conduction of the heater is also stopped.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a combustion control device for oil hot air blowers and the like.

Conventional configurations and their problems Due to the nature of the products, combustion equipment such as oil hot air blowers require sufficient attention to prevent fires, oil leaks, and other abnormalities.In particular, the combustion control circuit that controls and manages combustion is Care must be taken to avoid abnormal operations such as malfunctions and runaway operations. Recent advances in combustion technology have led to the adoption of microcomputers (hereinafter referred to as "microcomputers") for control circuits in many cases in response to complex combustion control methods that satisfy the requirements of variable combustion, -reduction of carbon oxides, etc. . Microcontrollers operate on weak signals,
Even if sufficient noise countermeasures are taken in the peripheral circuits, there will be no malfunction or runaway.Furthermore, static electricity may cause partial damage to the icon, so in the unlikely event that malfunction or runaway occurs. It is difficult to predict what the output state will be when the microcomputer loses its control ability. Therefore, fire,
There is a risk of oil leakage, etc. Conventionally, in order to prevent unsafe operations when a microcomputer runs out of control, a system has been created in which the microcomputer's program goes into an infinite loop and stops the product on the safe side when the microcomputer's program goes into an infinite loop and does not take the normal steps. Ta.

FIG. 1 is an illustration of a conventional example, and shows a control circuit for an oil hot air fan using a microcomputer. FIG. 1A shows a high-voltage circuit, and FIG. 1B shows a low-voltage circuit, and 1 is a power plug connected to a commercial power source. 2 current fuses, 3
is a 1 degree limit switch that opens when the internal temperature of the oil hot air fan becomes abnormally high, and supplies power to the power transformer 4, burner motor 5, pump circuit 6, and carburetor heater 7 necessary for maintaining combustion. By shutting off the fuel, combustion is stopped. On the other hand, the relay contact 8a is connected to the current fuse 2K on the primary side, the burner motor 5 on the secondary side, one end of the blower motor 9, and the normally open contact side of the relay contact 10a, and when the relay contact 8a is forced to close,
The burner motor 5 supplies combustion air, and the combustion heat is heated in a temperature order (
The blower motor 9 starts to send the air into the room. On the common terminal side of the relay 10a, that is, on the load side, there is an igniter 11 that operates for a certain period of time after energization and ignites the petroleum vapor gas.
A solenoid 12 that changes the amount of combustion air sent from the pernamoke 5 at the time of combustion switching is connected after being full-wave rectified by a diode bridge 14 via a normally closed contact of a relay 13a. Further, a pump circuit 6 for driving a pump 15 that supplies kerosene as fuel is also connected to the common terminal side of the relay 1a.

On the other hand, in FIG. 1B, a diode bridge 16 and a smoothing capacitor 17 rectify and smooth the alternating current power and convert it into a direct current. A is a single DC line that is tangent to the positive electrode side of the five diode bridges 16. →, Relay 8.13,
It is connected to one end of the PNP transistor 19, the emitter terminal side of the PNP transistor 19, and the input side of the stabilized power supply 2o. 21
The room temperature thermistor 22 detects the room temperature, and the burner thermistor detects the temperature of the vaporizer cylinder that changes the temperature to a state suitable for heating to vaporize kerosene.23 is the flame rod that detects the combustion state. The beliefs obtained from the thermistor 21, burner thermistor 22, and arene rod 23 are processed as combustion information within the microcomputer 24. 2
5 is a luck 1 translation switch. Reference numeral 26 denotes an F/V conversion circuit for converting the frequency into one voltage, the input of which is connected to the microcomputer 24, and the output of which is connected via a transistor 27 to the base of one transistor. A relay 10 and one end of a coil of a relay 18 that performs ○N10FF of the heater 7 that heats the vaporization cylinder are connected to a bus bar port connected to the collector of the transistor 19. Memo Relay 8.13.10.
In addition to 18 coils + QIi Mari Rehoku! l jino circuit 28
It is connected to the output terminal of the microcomputer 24 via.

At normal times, relay contact 8a118a is used at Hokugi Rokuji.

10a is open and combustion has stopped. The microcomputer 24 detects that the operation swing 25 is closed (i
) The f-sign wire 29 is set to W', the coil of the relay 18 is energized 17, and the relay contact 143a is closed. Then, energization is started to the heater of the vaporization cylinder, and the temperature of the vaporization cylinder rises when the burner thermistor 22 detects that the temperature has reached the appropriate temperature. ■When the temperature of the vaporizer cylinder reaches the appropriate value, the contact 18a opens, and instead the signal line 30 becomes H and the contact 8a closes.
Burner motor 5 operates. ■After a certain period of time after the contact 8a closes, the signal line 31 also becomes ゝゝa', the contact 10a closes, and at the same time as the igniter 11 starts operating, the pump circuit 6 is also energized and combustion starts. . ■It is monitored by the flame rod 23 that combustion is being maintained reliably, and if it is normal, the combustion state will continue to be maintained.

Items ① to ① above are combustion processing routines, which correspond to 32 in the flowchart shown in FIG. In FIG. 2, the pulse output 34 is a routine for outputting a pulse signal of about synchronization 2 to i 0 nl S from the signal line 33.
This is a routine that always goes through as long as the microcomputer 24 is operating normally, regardless of 0FF. When a predetermined pulse signal is output to the signal line 33, the pulse frequency is converted to voltage in the F/V converter circuit 26, turning on the transistor 27, and eventually the transistor 19 connects the DC fjJ line A power source to the ONX bus bar port. Supplied.

In the conventional example described above, a countermeasure against runaway or malfunction of the microcomputer 24 is taken by providing an F/V conversion circuit 26, but if the microcomputer 24 is partially destroyed due to static electricity or the like, for example, the signal line 29 or 31 is short-circuited. If an accident occurs and the signal is always ``V'', there is a risk that combustion may not be stopped or the carburetor cylinder may melt, resulting in an unsafe situation, and even if the microcomputer 24 can detect an abnormality, it cannot take any action. The problem was that there was no.

Purpose of the Invention The present invention was developed in view of the above-mentioned problems, and aims to prevent the microcomputer from becoming unsafe even when it is partially destroyed, malfunctioning, or running out of control due to static electricity, etc. .

In order to achieve the above object, the present invention uses a terminal that outputs an "H" or L signal when the microcomputer 24 detects an abnormality, and an abnormality processing routine. ', Record V
The pulse signal supplied to the input of the /F converter circuit 26 is
' or 'L'.

Description of examples An example of this will be described below with reference to FIG.

In FIG. 3, parts and symbols with the same number have the same name and function.Pl is the signal line 29, P2 is the signal line 31, P3 is the signal line 34 that drives the relay 13, and P4 signal line. This is the name of the output port of the microcomputer 24 connected to each of the cables 30. The PO outputs a "■" signal when the microcomputer 24 detects some abnormal condition 1k, such as the temperature of the carburetor cylinder becoming abnormally high or an ignition signal being input from the flame rod 23 even though it is not the sequence in which combustion should occur. The port that outputs to the signal line 35 is connected to the base of the transistor 37 via the resistor 36.On the other hand, in the present embodiment, the signal line 33 is connected to the resistor 38 inside the F/V converter circuit 26. The other end of the resistor 38 is connected to the capacitor 39 and the transistor 3.
7 collector.

FIG. 4 shows a schematic flowchart of a program processed inside the microcomputer 24 in this embodiment, and is a routine that normally checks the opening and closing of the operation switch 25 to determine whether or not combustion is to be performed. Operation switch ONJ
Based on the judgment at 40, the closed loop of 41 is set to the same size during OFF' operation, and the ('I] loop of 42 is set to the same size during operation.

The routine "abnormality detection" 43 for detecting an abnormality in the system is incorporated into a closed loop that is processed before the operation switch ONJ 40, and when an abnormality is detected, it branches to a loop 44 and processes 45 and 46. Execute.

At the time of writing, under normal conditions, the P port outputs "L", and the P1 boat to P4 boat are in the output state in a series of sequences, and the transmission line 33 is in the output state. A constant pulse is being output. Now, if the microcomputer 24 is partially destroyed while the Pl boat is fixed at "H" due to some reason such as static electricity, the coil of the relay 18 is energized and the contact 18a is closed, and the heater 7 is no longer energized.

When the temperature of the vaporizing cylinder rises abnormally and becomes on the verge of melting, the burner thermistor 22 detects an abnormality, and the "abnormality detection" routine 43 changes to a loop 44.

Then, in process 45, a signal is issued to set the P1 boat to P4 boat to "Y" without switching, and then, in process 46, the PO abort is set to 'Y'. When the signal line 35 becomes 'N', the transistor 37 is turned on. , the potential at the connection point between the capacitor 39 and the resistor 38 is fixed at OvK, and the F/V conversion circuit 26 is stopped +h, so the transistor 27 is also turned off, and the transistor 19 is turned off, and the power supply to the JlJ line is stopped. After that, no matter how true the signal line 29 is, the current to the coil of the relay 18 is stopped, so contact 1
8a is open! 1! The power supply to the heater 7 is also stopped.

In the embodiment described in -1-, the minimum necessary relays 10 and 18 are connected to the m-line port, but all relay loads may be connected. Also, when an abnormality is detected, p□
The port is set to d' and the F/V converter circuit 26 is stopped via the transistor 37, but it is also possible to use a logic gate element, and the F/V converter circuit 26 can also be controlled by the microcomputer 2.
Any device that has the function of a node-like final safety circuit that operates independently of the operation of the microcomputer 24 when the microcomputer 24 runs out of control can be used.

As described above, according to the present invention, the system can be maintained so that the entire system does not stop in an unsafe direction even in the event of a partial failure other than a complete stop due to a runaway microcomputer. In addition, by configuring the F/V conversion circuit, which is the final safety circuit in the event of a runaway microcomputer, to always stop even when a simple abnormality is detected, F/V conversion circuits can be prevented without intentionally causing the microcomputer to run out of control during circuit inspection. It also has the effect of confirming the V-transformation circuit work.

[Brief explanation of drawings]

Figures 1A and B are a circuit diagram of a conventional example, a second control circuit diagram, and Figure 4 is a program flowchart showing the operation of the same microcomputer. 10a... Pump relay contact, 18a...・Heater relay contact, 19...Transistor, 24.Microcomputer, 25...Operation switch, 26...F/Vi
fi times [B, 34 ・Pulse output routine, 43...
...Abnormality detection Luzhin, PO~P4...Microcomputer output boat.

Claims (2)

[Claims] (1) A microcomputer equipped with a combustion control routine or a safety processing routine, and a final safety circuit that shuts off peripheral circuits in the event of a runaway or malfunction of the microcomputer; and a terminal for outputting a signal at the time of the abnormality, so as to cause the final safety circuit to be created at the time of the abnormality,
4, 8, a combustion control device that is in contact with 4, 8 and 8. (2) An F/V conversion circuit is used as the final safety circuit, and the pulse output terminal is output from one output terminal of the microcomputer, and the logic of the signal output from the other terminal of the microcomputer when an abnormality is detected. 2. The combustion control device according to claim 1, wherein the sum or logical product is used as an input signal to the F/V conversion circuit.