JPH0730919B2 - Combustion device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a combustion device in which a combustion safety device is provided in a boiler or the like to safely perform combustion.

[Conventional technology]

In a combustion device such as a boiler, an ignition trial timing time for opening the fuel valve of the combustion gas and igniting is provided after the pre-purge timing time for releasing the residual gas in the combustion chamber, which is configured to obtain optimum ignition. Has been done.

[Problems to be Solved by the Invention]

However, in such a conventional combustion device, when the ignition operation by this is not performed for a long time, the air is replaced by the fuel and the burner is overcooled at the start of ignition in the cold season or in the morning. If so, the ignitability becomes extremely poor, and a single ignition operation will result in immediate lockout due to non-ignition. Therefore, the ignition operation must be repeated through a human reset operation until ignition occurs. There was a problem.

The present invention has been made in view of such a conventional problem, and it is possible to prevent ignition failure as much as possible while maintaining the fail-safe property that only the safety side failure occurs even if there is a component failure. The purpose is to obtain the device.

[Means for Solving the Problems]

In the combustion device according to the present invention, the fan motor is activated to start the pre-purge operation, and then the first combustion valve and the ignition device are activated to perform the ignition trial operation a plurality of times, and the combustor is ignited to generate the flame signal. Occurs,
A first combustion safety device that operates a second fuel valve in response to a detection signal from a flame detector that has detected this flame signal;
A second step of stopping the ignition trial operation if ignition is incomplete after the pre-purge operation is performed a plurality of times.
Combustion safety device, a timing time extension circuit for extending the ignition trial operation time and a timing time reduction circuit for shortening the ignition trial operation time, and the timing time extension circuit or timing time depending on the burner temperature or the power-on timing. And a selection circuit for selecting one of the shortening circuits.

[Action]

The timing time extension circuit in the present invention is automatically connected to the power source when the burner temperature is low or when the power is initially turned on, and by extending the time such as the prepurge timing and the ignition trial timing more than usual, the ignition and the combustion are more reliably performed. Moreover, after a stable operation, try to transfer the fire to the main fuel valve.

Example of Invention

An embodiment of the present invention will be described below with reference to the drawings. In FIG. 1, 1, 2 and 3 are relays, which are controlled by the first combustion safety device 5. 6 is a second combustion safety device which controls the relays 15 and 17. A flame detector 9 inputs a flame signal to the first and second combustion safety devices 5 and 6. TR is a transformer that transforms and supplies the voltage from the power supply 12 to the first and second combustion safety devices 5 and 6, and 1a, 2a, 3a, 15a and 17a are relays 1, 2, 3, 15, and 17 of each relay. Relay contact, 7 is relay contact 1a,
The first fuel valves 8,10 connected to the power supply 12 via 15,2a are the second fuel valve and the ignition device, respectively, which are connected to the power supply 12 via the relay contacts 1a15a, 2a, 3a. There is. 1
Reference numeral 1 denotes a heat request controller, through which a heat request determiner 14 is connected to a power supply 12. 13 is power supply via relay contact 1a
A fan motor connected to 12, and an alarm device 16 connected to the power supply 12 via a relay contact 17a.

Next, the operation will be described with reference to the timing charts shown in FIGS. First, the heat demand controller 11, which is an operation switch, is turned on. As a result, the heat demand discriminator 14
Inputs a signal such as 14S in FIG. 2 to the first and second combustion safety devices 5 and 6, whereby the relay 1 of the first combustion safety device 5 is energized and the relay contact 1a is It turns on. Then, the fan motor 13 starts operating like 13S in FIG. 2 to release the residual gas, and when the pre-purge timing ends, the relays 2 and 15 are energized to turn on the relay contacts 2a and 15a, and The fuel valve 7 of No. 1 is opened to supply the fuel gas to the combustion chamber, and in parallel with this, the ignition device 10 is operated (Fig. 2, 7S, 1).
0S). That is, the pre-purge timing A and the ignition trial timing B are alternately repeated by repeatedly turning on and off the first fuel valve 7 and the ignition device 10.

In this state, when the combustor emits a flame signal due to ignition, the flame detector 9 outputs a flame signal such as 9S in FIG.
Input to the first and second combustion safety devices 5 and 6. Therefore, the relay 3 is energized, the relay contact 3a is switched, and the second combustion valve 8 is opened as shown by 8S in FIG. 2 after the elapse of the post-ignition timing time C after flame detection, The large combustion of fuel is started.

On the other hand, if the flame does not occur even when the pre-purge and the ignition trial of the first combustion valve 7 and the ignition device 10 reach the set number of times, that is, when the time D has elapsed, the second combustion safety device 6 Energize relay 15,
The relay contact 15a is opened, and the above ignition operation is performed by the 15S of FIG.
As described above, the relay 17 is energized to turn on the relay contact 17a, thereby actuating the alarm device 16 and notifying the operator that ignition is impossible. Note that the other timing charts shown in FIG. 3 are the same as those shown in FIG. 2, and duplicate description thereof will be omitted.

FIG. 4 is a circuit diagram obtained by partially modifying FIG. 1, in which the relay 2 is connected to the collector of a transistor 4 as a semiconductor element, and the emitter of the relay 2 is connected to the relay TR.
Of the transistor 4, and the first and second combustion safety devices 5 and 6 are connected to the base of the transistor 4 via backflow prevention diodes D ₁ and D ₂ . This allows the relay 15 and the relay contact 15a to be omitted from the circuit.

In the circuit shown in FIG. 4, the relay 15 is omitted and the relay 2 is used as both the first and second combustion safety devices 5 and 6.
The same operation and effect as those of the above embodiment can be obtained with a simple configuration.

FIG. 5 shows an application example of another circuit connected to the secondary side of the transformer TR shown in FIG. In this application example, two sets of a post-ignition timing time extension circuit 21 and a timing time reduction circuit 22 are installed in parallel, and each of these circuits 2
1, 22 are connected to the secondary side of the transformer RT via a changeover switch 23. Then, the changeover switch 23
Is a switch changeover circuit equipped with a burner temperature sensor and power-on timer, which are also connected to the secondary side of the transformer TR.
It is designed to be automatically switched by 24,
The changeover switch 23 and the switch changeover circuit 24 constitute a selection circuit.

In this circuit, when the operation switch is turned on or when the burner is stopped for a long time and the operation is restarted, the switch changeover circuit 24 detects this and changes the changeover switch 23 to the timing time shortening circuit during normal use. Switch from 22 to the timing time extension circuit 21. Therefore, the post ignition timing and timed ignition timing for switching the energization from the ignition device 10 to the second fuel valve 8 are lengthened, and the post ignition ignition device called pilot only timing is turned off after the post ignition timing and the timed ignition timing. And then the first fuel valve 7
It is possible to lengthen the energization time to only. As a result, even when the burner is completely cold, the second fuel valve is ignited after the burner has been sufficiently warmed up. , So that the energization of the second fuel valve 8 can be started.

In addition, in the first and second combustion safety devices 5 and 6 that determine the downtime of the burner, the burner is operated from the time of power-on or not at the time of power request regardless of whether or not there is a heat request in order to extend the timing. Instead of turning on the power, power may be supplied from the time of operation, or power may be constantly supplied to measure the down time, or the down time may be estimated from the burner temperature.

Further, it is obvious that a discrete element, a cam, a heater type timer, an integrated circuit (analog or digital) or a microcomputer may be used for each combustion safety device.

Furthermore, in the combustion safety device that determines the burner down time, the post ignition and pilot-only timing lengths are lengthened. (A) Whether the heat is required or not ) Do not turn on the power at rest, supply power from the time of operation, (c) always supply power to measure the rest time, and (d) estimate the rest time from the burner temperature to measure the rest time. be able to.

〔The invention's effect〕

As described above, according to the present invention, after the fan motor is operated to start the pre-purge operation, the first combustion valve and the ignition device are operated to perform the ignition trial operation a plurality of times to ignite the combustor. Generates a flame signal, the first combustion safety device that operates the second fuel valve in response to the detection signal from the flame detector that detects this flame signal, and the ignition failure after the multiple pre-purge operations. In a complete case, a second combustion safety device for stopping the ignition trial operation, a timing time extension circuit for extending the ignition trial operation time, a timing time reduction circuit for shortening the ignition trial operation time, a burner temperature or The timing time extension circuit or the timing time reduction circuit according to the power-on timing Since it has a configuration with a selection circuit that selects one of them, for example, even after the burner has been off for a long time, ignition combustion is performed safely, reliably, and automatically while maintaining fail-safety. There is an effect that you can get what you can. Further, the respective times of the prepurge timing and the ignition trial timing can be arbitrarily set according to the burner temperature and the power-on timing, and a more safe and reliable ignition combustion can be realized.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing a combustion apparatus according to an embodiment of the present invention, FIGS. 2 and 3 are timing charts showing signals of respective parts of the circuit shown in FIG. 1, and FIG. 4 is a part of FIG. FIG. 5 is a circuit diagram showing a modified circuit of FIG. 5, and FIG. 5 is a block connection diagram of essential parts showing a combustion apparatus according to another invention of the present invention. 5 is the first combustion safety device, 6 is the second combustion safety device, 7,
8 is a fuel valve, 7 is a first fuel valve, 8 is a second fuel valve, 10
Is an ignition device, 21 is a timing time extension circuit, 22 is a timing time reduction circuit, and 23 is a changeover switch. In the drawings, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] 1. A fan motor is actuated to start a pre-purge operation, and then a first fuel valve and an ignition device are actuated to carry out an ignition trial operation a plurality of times, and when a combustor generates a flame signal by ignition. A first combustion safety device that operates a second fuel valve in response to a detection signal from a flame detector that detects this flame signal, and the ignition if the ignition is incomplete after a plurality of pre-purge operations. A second combustion safety device for stopping the trial operation, a timing time extension circuit for extending the ignition trial operation time, a timing time reduction circuit for shortening the ignition trial operation time, and the burner temperature or the power-on timing depending on the burner temperature. Select either timing time extension circuit or timing time reduction circuit Combustion apparatus having a selection circuit.