JPS6357699B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a combustion safety control device having a function of automatically performing a predetermined ignition operation according to a preset sequence when a heat request occurs.

A typical combustion safety control device controls the fan motor, pilot valve, igniter, and main valve so that when a heat request occurs, steady combustion begins after pre-set pre-purge, ignition trial, and pilot-only timings. During this time, if something goes wrong, such as poor ventilation,
If an ignition failure occurs, the sequence is always shifted to the safe side and then the operation is stopped. Therefore, even if an abnormality occurs, there is no risk of release of unburned gas or explosion, but if these abnormalities are caused by faulty parts such as broken wires, it is not possible to repair the fault. It becomes necessary. However, even if the anomaly occurs at some stage in the sequence, such as during the ignition trial timing, the sequence will proceed to stop igniter operation and close all valves, and this operation will continue until the anomaly occurs at some other point in the sequence. This is the same even when an abnormality occurs, so after the operation has stopped, it is impossible to determine at what stage the abnormality has occurred, making it difficult to determine the location of the failure.

This invention was made in order to eliminate the above-mentioned drawbacks of the conventional technology, and by displaying the type of each timing in progress with a display lamp and blinking this display lamp when an abnormality occurs, The purpose of the present invention is to provide a combustion safety control device that allows the timing of occurrence of an abnormality to be easily confirmed in the event of an accident.

Next, an embodiment of the present invention will be described with reference to the drawings. In the figure, a fan motor FM, a pilot valve PV, an igniter IG, and a main valve MV are connected between terminals 1 and 2 connected to an AC power source via a control circuit made up of a plurality of contacts. Electric power is also supplied from the AC power supply to the combustion safety control circuit 4 via the transformer 3.

This combustion safety control circuit 4 generates a prepurge signal PPT, a pilot valve drive signal PVT, an igniter stop signal IGT, and a main valve drive signal MVT according to a preset sequence when a heat request occurs. , and if the predetermined operation is not performed by these signals,
It has the function of immediately cutting off each drive signal and outputting an alarm signal ALT consisting of pulses of a predetermined frequency. Since a combustion safety control circuit having such a function is already known, a detailed explanation thereof will be omitted.

When the occurrence of heat demand is detected, a pre-purge signal is sent at the pre-set pre-purge timing.
PPT is output, which causes transistor Q
1 turns on and relay 1K operates. The operation of this relay 1K turns on its contact 1K1, driving the fan motor FM to blow air into the combustion chamber of the combustor, and this air blowing turns on the air flow switch AF. After confirming that air is being blown normally by turning on the air flow switch AF, the combustion safety control circuit 4
outputs the pilot valve drive signal PVT after the pre-purge timing ends, which turns on the transistor Q2. When transistor Q2 turns on, relay 2K operates and its contact 2
K1 is turned on, pilot valve PV and igniter
IG works. This state continues until the predetermined ignition trial timing ends, and if the pilot burner ignites during this time, a flame detector (not shown) detects this and supplies a flame detection signal to the combustion safety control circuit 4. This causes the igniter stop signal IGT
is output and connected to relay 3 via transistor Q3.
When K operates and its contact 3K1 switches, and then the main burner drive signal MVT is output,
Relay 4K operates via transistor Q4,
When the contact 4K1 turns on, the main burner MV opens, and from this point on, a steady combustion state begins.

In addition, the above signals PPT, PVT, IGT, MVT are
The signals are supplied to latch circuits 5a to 5d, respectively. That is, when the signal PPT is output, the transistor Q1 is turned on and at the same time, the latch circuit 5a is latched and its output becomes H level. This H level signal is supplied to one input end of the AND circuit AN1 via a priority circuit 6 which is a combination of a plurality of inverters. Further, the other input terminal of the AND circuit AN1 is supplied with a pulse-like alarm signal ALT of a constant frequency, which is output when the combustion safety control circuit 4 detects some kind of abnormality, via the inverter In. However, in the normal state, the alarm signal ALT is not output, so the latch circuit 5
The output of a passes through the AND circuit AN1 as it is and is supplied to the transistor Q5, turning it on.
As a result, the display lamp LD1 lights up. Next, when the pre-purge timing ends and the ignition trial timing begins, the pilot valve drive signal
The latch circuit 5b is latched by PVT,
The transistor Q6 is turned on via the AND circuit AN2, and the display lamp LD2 lights up, but as the output of the latch circuit 5b becomes H level,
Since the transistor Q5 is turned off by the priority circuit 6, the indicator lamp LD1, which had been lit up until then, is turned off. This relationship is the same for the signals IGT and MVT, and when the latch circuit 5c is latched by the signal IGT, the transistor Q7 is turned on and the indicator lamp LD3 is turned on, and at the same time the other indicator lamps LD1 and LD2 are turned off. and then the signal
When the latch circuit 5d is latched by the MVT, the indicator lamp LD4 is turned on and at the same time the other indicator lamps LD1, LD2, and LD3 are turned off.

On the other hand, if something abnormal occurs during the sequence from pre-purge timing to steady combustion state,
The combustion safety control device 4 sets the sequence to the safe side, that is, cuts off the signals PPT, PVT, IGT, and MVT, and controls the fan motor FM, pilot valve PV, and igniter.
IG and main valve MV are all inactivated, and an alarm signal ALT is output. This alarm signal ALT is input to the AND circuits AN1 to AN4 via the inverter In, so
One of the display lamps LD1 to LD4 flashes.

For example, when the sequence preset in the combustion safety control circuit 4 has progressed to the ignition trial timing, the relay 2K is activated by the signal PVT, and the indicator lamp LD2 is lit, for some reason the pilot burner Assume that the ignition does not occur. In this case, the combustion safety control circuit 4 determines that ignition has failed because the flame detection signal has not been supplied by the end of the ignition trial timing, and at the same time cuts off the signals PPT and PVT that have been output until then. Outputs alarm signal ALT. At this time, since the latch circuit 5b is already latched, its output is
The signal is converted into a pulse by the AND circuit AN2, and the display lamp LD2 blinks. Therefore, the administrator can check that the display lamp LD5 is blinking.
It is possible to know that an abnormality has occurred during the ignition trial timing. Therefore, the cause of the abnormality can be easily determined, and the failure can be quickly dealt with.

In the above embodiment, four indicator lamps are used to indicate each state of pre-purge, ignition trial, and steady combustion, but additional indicator lamps are provided to indicate abnormalities such as extinguishing the flame, air flow switch failure, and dry firing. If provided, even more types of abnormalities can be dealt with.

As described above, according to the present invention, when an abnormality occurs during the progress of a sequence, the stage at which the abnormality has occurred can be easily identified by blinking one of the display lamps indicating the status of the sequence. This has the effect that finding the location of the failure, which is necessary for speedy repair, is greatly facilitated.

[Brief explanation of the drawing]

The figure is a circuit diagram of a combustion safety control device according to an embodiment of the present invention. 1, 2...terminal, 3...transformer, 4...combustion safety control circuit, 5a-5d...latch circuit, 6...priority circuit, 1K-4K...relay, 1K1-4K1...contact,
LD1~LD4...Indication lamp, AN1~AN4...
AND circuit, In...inverter, FM...fan motor, PV...pilot valve, IG...igniter, MV...main valve.

Claims (1)

[Claims] 1. A combustion safety control circuit that sequentially outputs output signals for driving the elements necessary for steady combustion in the combustor according to a preset sequence, and when each of the above output signals is supplied. A latch circuit that is latched, a priority circuit that prioritizes the output of the latch circuit that was latched last among the outputs of each latch circuit, the output of the latch circuit selected by this priority circuit, and the combustion safety A combustion safety control device comprising an indicator lamp provided corresponding to each of the latch circuits so as to blink in response to a pulsed alarm signal output when the control circuit detects an abnormality.