JPH01111135A - Combustion control circuit - Google Patents

Abstract

PURPOSE:To provide a positive termination of combustion if a discharging pipe is disconnected and then provide a prevention of leakage of discharging gas by a method wherein a pulse generating circuit is connected to the discharging pipe through a switching element, a discharging pipe comparing and discriminating circuit is connected and a signal from the comparing and discriminating circuit is inputted to a microcomputer. CONSTITUTION:A pulse generating circuit 36 is connected to a discharging pipe 23 through switching elements 14 and 16 for applying an electric current to the discharging pipe 23 only when a pulse outputted by the pulse generating circuit 36 is set at a predetermined level. A comparing and discriminating circuit 37 discriminating whether an electric current is lowed in the discharging pipe 23 or not is connected to the discharging pipe 23. An output side of the comparing and discriminating circuit 37 is connected to an input side of the microcomputer 32 for terminating operation in case that an electric current is not flowed in the discharging pipe 23. The pulse generating circuit 36 may flow an electric current to the discharging pipe 23 only when a generated pulse is at a predetermined level of 'H' or 'L'. The comparing and discriminating circuit 37 connected to the discharging pipe and the microcomputer 32 receiving a signal from the comparing and discriminating circuit may receive the signal and if the electrical current flows in the discharging pipe 23, the system judges that the discharging pipe is normal and if the electric current does not flow, it is judged that the discharging pipe is disconnected and then the combustion is terminated.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a combustion control circuit for a forced air supply/exhaust hot air heater using an exhaust pipe.

Conventional technology The conventional technology is to attach the exhaust pipe and air supply pipe of the supply and exhaust pipe to the exhaust pipe P installed on the back of the vessel body and the air supply pipe installation port, respectively, and connect the exhaust pipe and air supply pipe to the vessel body. It has an actuator near the main body, which operates a safety switch such as a microswitch installed on the back of the main body, and connects it to the combustion control circuit of the main body. This safety switch consists of the combustion control circuit of the vessel, a stainless steel exhaust pipe connected to this, a stainless steel supply and exhaust pipe integrally connected to this exhaust pipe, and a synthetic valve connected to this supply and exhaust pipe. It has a closed circuit consisting of a coiled metal wire of a resin-coated and combustible air supply pipe. (For example, Jikko Sho 58-2
7255 Publication) Problems to be Solved by the Invention In the conventional combustion control circuit described above, it is difficult to prevent the exhaust pipe from detaching for some reason and the combustion exhaust gas from being discharged into the chamber (23) and polluting the indoor air. Although it is effective, the exhaust pipe, air supply/exhaust pipe, and air supply pipe must be integrated to ensure airtightness and conductivity, resulting in poor workability and high cost. In addition, since current is continuously passed through the exhaust pipe, moisture in the combustion exhaust gas and SO
There is a risk that the condensation of 2 gases, etc. will accelerate electrolytic corrosion and cause holes in the exhaust pipe, causing combustion exhaust gas to leak into the chamber (23).

Means for Solving the Problems The present invention has been made in order to eliminate the above-mentioned drawbacks.The present invention has been made in order to eliminate the above-mentioned drawbacks. A comparison circuit is connected to the exhaust pipe through a switching element that allows current to flow through the exhaust pipe only when the current is at the level of The end is connected to the input side of a microcomputer that stops operation when no current is flowing through the exhaust pipe.

Operation With the above configuration, the pulse generation circuit connected to the exhaust pipe via the switching element supplies current to the exhaust pipe only when the generated pulse is at a predetermined level of "H" or "L" (for example, "H"). A comparison judgment circuit connected to the exhaust pipe and a microcomputer that receives the signal from this comparison judgment circuit determine that the exhaust pipe is installed normally if current is flowing through the exhaust pipe. If the current is not flowing, it is determined that the exhaust pipe is disconnected and control is performed to stop combustion.

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

In Fig. 1 showing the circuit of this embodiment, 1 is a transformer for a separate power supply, and the secondary side of the transformer 1 is half-wave rectified by a diode 2, flattened by a capacitor, and resistor A constant voltage circuit is constituted by a Zener diode 35 via a Zener diode 35. Resistance 5 to 10. Capacitor 11. The comparator 15 and the diode 12 constitute a pulse generating circuit (astable multi-pipe rake) 36, which outputs a pulse as shown in FIG. When this pulse is "H", the switching element (transistor) 14 is turned on through the resistor 13, and the switching element (transistor) 18 is turned on through the resistor 17. Therefore resistance 1
A current flows through the exhaust pipe 23 through the exhaust pipe 9 . If the exhaust pipe 26 is conductive, the non-inverting input () of the comparator 27 in the comparison/judgment circuit 67 becomes smaller than the inverting input (○) voltage by the resistor 25.26.

The output of the comparator 27 becomes "L". Therefore, current flows through the photocoupler 30-a via the resistor 28, so the photocoupler 60-b is turned on and the current flows through the resistor 38.

The transistor 39 is turned on and "L" is input to the microcomputer 62. The microcomputer 2 determines that it is normal when "L" is input, and determines that it is abnormal when "H" is input, and turns off the driver 36. When the driver 33 is turned on, the operation control relay 34 is turned on and becomes in operation, and at the same time, a current is passed through the photocoupler 29-a, the photocoupler 29-b is turned on, and the pulse generation circuit is activated, as shown in FIG. Output a pulse.

The operation of this embodiment having the above configuration will be explained.

During operation, the driver 33 is turned on and the operation control relay 34 is turned on to enter the operational state, and current flows through the photocoupler 29-a, the pulse generation circuit 36 is activated as described above, and the pulse shown in FIG. 2 becomes "L". A current is applied to the exhaust pipe 26 at this time. While the operation is stopped, no current flows through the photocoupler 29-a and the photocoupler 29-b is turned off, so the pulse generation circuit 66 does not operate and the transistor 14゜1
8 is turned off, and no current flows through the exhaust pipe 23.

Similarly, when the pulse shown in FIG. 2 is "L", the transistors 14 and 18 are turned off, and no current flows through the exhaust pipe 23. However, in these cases, since the non-inverting input voltage of the comparator 27 is QV through the resistor 20, the output of the comparator 27 is "L", and the photocoupler 30
-b is turned on, and the input to the microcomputer 32 is "L".

If the exhaust pipe 23 is disconnected, the pulse generation circuit 66
Only when the voltage is low, the divided voltage value of the resistor 19.20 is input to the non-inverting input ■ of the comparator 27, but this is the inverting input O.
By setting the resistance so that it is larger than the voltage, the output of the comparator 27 is turned off.

Therefore, since no current flows through the photocoupler 60-a, the photocoupler lo-b is turned off, and the transistor 3
9 is also turned off, the microcomputer 32 is connected to “
H" signal is input. Therefore, the microcomputer 32 determines that there is an abnormality, so the control relay 34 is turned off and does not operate.

7P Therefore, the detection of the exhaust pipe 26 coming off is possible when the engine is running and the second
This is performed only when the pulse shown in the figure is "■(".

Koda is the moisture and SQ contained in the exhaust gas when it is combusted.
Corrosive substances such as 2 gases condense in the exhaust pipe 23.

Continuing to apply current to the exhaust pipe 23 will cause electrolytic corrosion and create a hole in the exhaust pipe 26, increasing the risk of exhaust gas leaking into the chamber (23), so the current is passed through the exhaust pipe 23. We are trying to minimize this as much as possible.

In addition, the transformer 1 is powered separately from the power source of the microcomputer 62, and the signal width and width are also connected to the exhaust pipe 23 by using photocouplers 29-a, 29-b and photocouplers 30-a, 30-b. The power supply of the microcomputer 32 is completely isolated. This is because when the flame rod method is used for flame detection, the flame current is passed through the vessel body, so the microcomputer 32 side and the exhaust pipe 23 side are insulated to prevent conduction between the microcomputer 32 side and the vessel body side and false detection. There is a need to.

Effects of the Invention In the present invention, a pulse generation circuit is connected to the exhaust pipe via a switching element, an exhaust pipe comparison judgment circuit is further connected, and a signal from the comparison judgment circuit is inputted to the microcomputer. Current is passed through the tube only when the pulse is at a predetermined level (for example, H), and if the exhaust pipe is disconnected, combustion is reliably stopped and exhaust gas leakage is prevented. This is highly effective in improving safety by preventing holes from forming in the exhaust pipe due to corrosion.

[Brief explanation of the drawing]

FIG. 1 is a combustion control circuit diagram showing one embodiment of the present invention, and FIG.
The figure is an output pulse diagram of the pulse generating circuit. 14, 18... switching elements. 23...Exhaust pipe, 32...Microcomputer. 66...Pulse generation circuit. 37... Comparison/judgment circuit.

Claims (1)

[Claims] In a combustion control circuit that exhausts combustion exhaust gas outdoors via an exhaust pipe (23) attached to the body, the exhaust pipe (23)
3), the pulse generation circuit (36) is connected to this pulse generation circuit (
36) are connected via switching elements (14) and (18) that allow current to flow through the exhaust pipe (23) only when the pulse output from the exhaust pipe (23) is at a predetermined level of "H" or "L", and A comparison judgment circuit (37) for determining whether current is flowing or not in the exhaust pipe (23) is connected to the pipe (23), and the output side of this comparison judgment circuit (37) is connected to the exhaust pipe (23).
A combustion control circuit characterized in that the combustion control circuit is connected to the input side of a microcomputer (32) that stops operation when no current flows through the combustion control circuit (23).