JPS5925924B2 - Combustion control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a combustion control device that reliably continues combustion even if the rotation of a blower motor changes in response to switching of combustion output.

FIG. 1 shows the control circuit of a conventional combustion device, namely, 1 is a commercial power supply, 2 is a starting switch, 3 is a pre-purge timer, 31 is its contact, 4 is a blower motor, 41
5 is a wind flow switch, 5 is a fuel control means for controlling the supply of fuel to the burner, and 6 is an igniter.

Here, the wind flow switch 41 uses a diaphragm to convert wind pressure into a displacement amount to operate the switch, or uses self-heating of a thermistor to switch by changing the resistance value between when there is wind flow and when there is no wind flow. It is configured to operate.

- Also, the fuel control means 5 includes a solenoid valve, a pump, etc.

In the above configuration, when the switch 2 is first closed, the prepurge timer 3 and the blower motor 4 operate to perform prepurge.

Further, when the blower motor 4 is operated and an air flow greater than the expected air flow is applied to the burner, the air flow switch 40 is turned on.

When the scheduled time (prepurge time) has elapsed, the contact 31 of the prepurge timer 3 is turned on.

When the wind flow switch 41 and the timer contact 31 are turned on in this manner, power is supplied to the fuel control means 5 and the igniter 6, fuel is supplied to the burner, the igniter 6 is operated, and combustion is started.

If a malfunction occurs in the blower motor 4 and the intended air flow is not applied to the burner, the air flow switch 41 is turned off, power supply to the fuel control means 5 and the igniter 6 is stopped, and combustion is stopped. , ensure safety.

When using a diaphragm as described above or a thermistor as the airflow switch 41, the minimum on-rewell (minimum wind pressure or wind speed at which the airflow switch 41 can be turned on) is set so that the switch itself can operate reliably.
Must be set to a certain value or higher.

For this reason, in burners that switch the combustion output between large and small, when the combustion output is small, the amount of air required for the burner decreases, which reduces the airflow applied to the burner, causing the airflow switch to turn off and combustion. The problem was that the system would stop.

SUMMARY OF THE INVENTION An object of the present invention is to provide a highly safe combustion controller that eliminates the problems seen in the conventional example and prevents combustion from stopping even when the combustion output is switched from high to low.

One embodiment will be described below with reference to the accompanying drawings.

For convenience, parts that are the same as those in Figure 1 are given the same symbol as - above.
The explanation was omitted.

In FIG. 2, 71 and 72 are interlocking output changeover switches, and when they are turned on, the combustion output becomes small.

8 is a relay, and 81 is its contact.

The contact 81 is connected in parallel to the wind current switch 41.

9 is a fuel supply amount control means such as a solenoid valve for switching the amount of fuel supplied to the burner between large and small; 10 is an air blowing amount control means such as a solenoid damper and a motor damper for switching the amount of air blown to the burner between large and small. be.

As mentioned above, the configuration of this embodiment has one end of the commercial power supply 1,
The start switch 2, the pre-purge timer contact 31, the wind flow switch 41, the output changeover switch 72 for switching the combustion state of the burner between large and small, the fuel supply means 9, and the other end of the commercial power source 1 are connected in sequence to form a closed circuit, The starting switch 2
and the prepurge timer contact 31 and the other end of the commercial power supply 1, the prepurge timer contact 31 is kept open for a predetermined time after the start switch 2 is turned on, and kept open for a predetermined time. The pre-purge timer 3 and the blower 4 that sends combustion air to the burner are connected in parallel, and a relay contact 81 is provided in parallel with the airflow switch 41, and the connection point between the airflow switch 41 and the output changeover switch 72 and the airflow switch 41 are connected in parallel. A relay 8 having a coil and turning on the relay contact 81 by excitation of the coil, a fuel control means 5, and an igniter 6 are connected in parallel to the other end of the commercial power supply 1. The output selector switch 72 is connected in series.
(a second output changeover switch 71 is provided,
Air blowing amount control means 10 is provided in parallel with the fuel supply means 9.

In the above configuration, when the combustion output is low, the switch 71
．． 72 is off, and therefore the relay 8, fuel supply amount control means 9, and air blowing amount control means 10 do not operate, so that they perform exactly the same operations as in the conventional example.

Next, the operation when the combustion output is small will be explained.

After switches 71 and 72 are turned on, switch 2 is turned on.

Then, power is supplied from the commercial power supply 1 to the prepurge timer 3 and the blower motor 4.

Then, the blower motor 4 operates, but since the prepurge timer contact 31 is off, the blower amount control means 10 is also off.
A large blast of air is applied to the burner, and for this purpose the air flow switch 4
1 turns on.

When the scheduled time has elapsed, the timer contact 31 is turned on.

At the same time, current flows to relay 8 through switch 2, timer contact 31, and wind flow switch 41, and relay 8 turns on.
The relay contact 81 is turned on, and the relay 8 is self-held, so that even if the wind flow switch 41 is turned off, power is supplied to the fuel control means 5 and the like through the relay contact 81.

Further, at the same time that the timer contact 31 is turned on, the fuel control means 5, the igniter 6, the fuel supply amount control means 9, and the air blowing amount control means 10 are energized, and combustion is started at a small output.

The burner air flow rate is small, so the airflow switch 41 is turned off, but since the relay 8 holds itself, it is equivalent to the airflow switch 41 holding itself, and the airflow switch 41 is turned off via the relay contact 81. Since the power supply to the fuel control means 5 and the like is maintained, combustion continues.

If the air flow applied to the burner decreases for some reason during pre-purging or high output combustion, the MJ switch 41 will turn off, and even if the combustion output is set to a low value, the relay 8 will not turn on. Therefore, since the relay contact 81 is not turned on, even if the contact 31 is closed after the pre-purge is completed, the air current switch 41 and the relay contact 81 are both off, so the fuel control means 5 etc. are not energized and the combustion state does not occur. Therefore, the safety of the burner is maintained.

As described in detail above, according to the present invention, when the combustion output is small, the combustion controller operates regardless of the operation of the air flow switch. Therefore, it can be determined whether the blower motor is malfunctioning or not, and the safety is extremely high.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing a conventional example, and FIG. 2 is a circuit diagram showing an embodiment of the present invention. 4...Blower motor, 31...Contact (for pre-purge), 41...Air flow switch, 81...
·····contact.

Claims (1)

[Claims] 1 A closed circuit is constructed by sequentially connecting a start switch, a pre-purge timer contact, a wind flow switch, an output selector switch that changes the combustion state of the burner to large or small, a fuel supply means, and the other end of the commercial power source to one end of the commercial power source. and between the start switch and the pre-purge timer contact and the other end of the commercial power supply, the pre-purge timer contact is kept open for a predetermined time after turning on the start switch, and kept open for a predetermined time. A pre-purge timer and a blower that sends combustion air to the burner are connected in parallel, a relay contact is provided in parallel with the airflow switch, and a connection point between the airflow switch and the output selector switch is connected to the other end of the commercial power source. A relay having a coil and turning on the relay contact by excitation of its fill, a fuel control means, and an igniter are connected in parallel, and the relay operates in series with the output changeover switch. A second output selector switch is provided,
A combustion control device including an air blowing amount control means in parallel with the fuel supply means.