JPS6323450B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a control device for a combustion machine, and particularly to a control device for a combustion machine, in which a post-purge operation can be easily performed using a control switch that is activated in response to a flame detection operation.

This type of device connects the drive circuit for ignition combustion via a control switch, and if there is no flame detection signal within a certain time after activation of this switch, the switch is deactivated, and flame is detected within that time. When a signal arrives, the switch continues to operate. Of course, the fan motor is also being driven during this time.

The present invention focuses on the point that the control switch is temporally controlled according to the flame detection signal, and connects a post-purge driver to the rear stage of this switch to perform time control in the same way as the switch, and controls the contacts of this driver. This is inserted into the power supply path of the fan motor, and an example thereof will be described below with reference to the drawings.

Reference numeral 1 is a commercial power source, which is connected in series with a power switch 2 that is linked to a power switch that opens and closes the gas supply path, and a fan that supplies combustion air to the burner and discharges combustion exhaust simultaneously with circulating indoor air. A motor 3 and a power transformer 4 are connected in parallel in this order, and an ignition device 6 is connected in parallel after the transformer via an ignition relay contact 5. 7 is a small switch 2 located after the ignition device 6.
A relay contact for supply gas connected in series to the ignition solenoid valve 8 for the ignition burner and the main solenoid valve 9 for the main burner.
are connected in parallel to power supply 1. 10 is a detection activation switch for controlling the opening and closing of the main solenoid valve 9 depending on the indoor temperature, etc.; 11 is a post-purge relay contact connected in parallel to the control switch 2; and 12 is a post-purge relay contact provided in the secondary winding of the power transformer 4. This is a flame detector that detects the flame of the ignition burner.

Here, a relay control circuit for controlling each of the relay contacts 5, 7, and 11 is connected to the other secondary winding of the power transformer 4, and will be explained below.

13 is a full-wave rectifier connected to the secondary winding, and a border-colored LED 14 for power display, a smoothing capacitor 15, and a timer circuit 16 for maintaining constant voltage are connected in parallel in this order.
A transistor control switch 17 is connected in series at the subsequent stage, and this control switch 17 is controlled by a timer circuit 16. Here, the timer circuit 16 includes a first comparator 19 that outputs a low potential as the charging potential of the first capacitor 18 increases, and a second comparator that outputs a high potential as the charging potential of the second capacitor 20 increases. 21 and these comparators 1
It consists of a PNP type timer transistor 22 whose bases are connected to the output terminals of switches 9 and 21, and the collector and emitter of the timer transistor 22 are connected in parallel to a constant voltage diode for the control switch 17. Therefore, when either the first comparator 19 or the second comparator 21 outputs a low potential, the timer transistor 22 becomes conductive and the control switch 17 becomes non-conductive, and both comparators 19 and 21 output a high potential. At this time, the timer transistor 22 is non-conductive and the control switch 17 is made conductive. The charging time for inverting the first comparator 19 of the first capacitor 18 is about 30 seconds at most, and the charging time for inverting the second comparator 21 of the second capacitor 20 is about 5 seconds at the shortest. It is set as.

Further, 23 is a short-circuiting transistor connected in parallel to the first capacitor 18, the base of which is connected to a flame detection circuit to be described later, and when conductive, stops the charging of the first capacitor 18 and discharges it.

Reference numeral 24 denotes an automatic return type overheat prevention switch connected in series after the control switch 17, and is installed at a suitable position in the combustor.

25 is a drive circuit connected after the overheating prevention switch 24, and includes a third comparator 27 that outputs a low potential due to an increase in the charging level of the third capacitor 26;
An NPN type ignition transistor 29 has a base connected to the output terminal of the third comparator 27 and an ignition relay 28 connected in series to the collector side, and a branch connection is made to the collector of this transistor via a first diode 30. The second gas supply relay 31
connected in series to the collector via diode 32
It consists of an NPN type holding transistor 33.
Therefore, the ignition transistor 29 is connected to the third comparator 2
The ignition relay 28 and the gas supply relay 31 are operated until the voltage 7 is reversed to a low potential output, and only the gas supply relay 31 is operated when the holding transistor 33 is conductive. Here, the charging time for the third capacitor 26 to invert the third comparator 27 to a low potential is set to about 40 seconds at most.

Note that no resistance element is connected to the emitter of the ignition transistor 29, and the base of the holding transistor 33 and the input terminal of the third capacitor 26 of the third comparator 27 are connected to a flame detection circuit, which will be described later. It is connected to.

Further, 34 is a red LED connected to the collector of the holding transistor 33, which indicates the normal combustion state of the ignition burner.

Reference numeral 35 denotes a flame detection circuit that operates according to the detection output of the flame detector 12 using flame rectification, and includes a pair of field effect transistors 37 and 38 (hereinafter referred to as No. 1FET3
7. a second FET 38); an NPN relay transistor 40 whose base is connected to the drain of the second FET 38 via a third diode 39;
NPN type flame detection transistor 4 whose base is connected to the collector of this relay transistor 40
Consists of 1. Here, the drain of the first FET 37 is connected to the base of the holding transistor 33,
The collector of the flame detection transistor 41 is connected to the base of the shorting transistor 23 via a constant voltage diode, and is branch-connected to the input terminal of the third capacitor 26 of the third comparator 27 via a fourth diode 42. . Therefore, at the time of flame detection, the first
When the second FETs 37 and 38 are non-conductive, the relay transistor 40 becomes conductive and the flame detection transistor 4
1 becomes non-conductive, the holding transistor 33 becomes conductive, and the third comparator 27 receives a high potential separately from the charging potential of the third capacitor 26 via the fourth diode 42, and is immediately inverted, and becomes a low potential. The signal is output to make the ignition transistor 29 non-conductive.

Reference numeral 43 denotes a post-purge relay connected after the flame detection circuit 35, which closes the electrically supplied contact 11 when the control switch 17 is turned on.

44... are the first to third capacitors 18, 20, 2
This is a diode for assisting the discharge of 6.

Next, the operation will be explained. First, the switch is opened to supply gas, and the switch 2 is closed in conjunction with the operation. Then, the fan motor 3 is driven to perform a so-called prepurge inside the combustor. During this time, the first
Although the comparator 19 has a high potential output, the second comparator 2
1 is a low potential output, the control switch 17 is non-conductive, and the relays 28, 31, and 43 are not operating. This prepurge time is about 5 seconds for the second comparator 21 to invert to a high potential output, and the second comparator 21
When the control switch 17 becomes conductive due to the reversal of 1, the post-purge relay 43 is powered on, and the ignition relay 28 and the gas supply relay 31 are powered on via the ignition transistor 29. When the contact 11 is closed, the ignition operation is started, and when the ignition relay contact 5 and the gas supply relay contact 7 are closed, the ignition burner is ignited and burned by the ignition device 6, and the flame is detected by the detecting object. 12 detects and outputs it to the detection line 36, and the first and second FETs 37, 3
8 becomes non-conductive. Then, the holding transistor 33 becomes conductive, causing the LED 34 to light up and the gas supply relay 31 to continue operating, and the flame detection transistor 41 becomes non-conductive, causing the third comparator 27 to continue operating.
is immediately inverted to a low potential output, thereby rendering the ignition transistor 29 non-conductive and the shorting transistor 23 conductive. When this ignition burner ignites and burns in a short period of time (within about 30 seconds), the first capacitor 18 is short-circuited while the charging level is still low, and the first comparator 19 is inverted to a low potential output. However, the control switch 17 continues to be conductive due to the high potential outputs of the first and second comparators 19 and 21. However, the ignition combustion was delayed and the 1st and 2nd FETs 37 and 38
When the voltage continues to conduct, the charging level of the first capacitor 18 increases and after about 30 seconds, the first comparator 19 becomes a low potential output, and the control switch 17 becomes non-conductive and the voltage is output to the drive circuit 25 and the subsequent stage. The power supply is immediately cut off. Also, in this case, even if the first comparator 19 fails and the control switch 17 is conductive, the third comparator 27 will be changed to a low potential output after about 40 seconds as the charging level of the third capacitor 26 increases. The ignition transistor 29 is made non-conductive and the ignition relay 28 and the gas supply relay 31 are stopped from operating. If the first and third capacitors 18 and 26 stop operating while being charged in this way, they can only be restarted after the power source 1 is turned off and discharged.

While the ignition burner is igniting and burning and outputting a flame detection signal, the main burner is supplied with gas and burns in response to the opening and closing of the detection activation switch 10.
Further, when a misfire occurs due to blowout, etc., or when the overheating prevention switch 24 is opened, the same operation as when ignition is delayed is performed.

Next, when the burner is closed and the burner switch 2 is opened after the prescribed burner combustion, the gas supply is stopped and the burner is extinguished, but power is not supplied to the fan motor 3 and the control circuit because the contact 11 is closed. ing. In addition, the flame detection signal is cut off to extinguish the burner, and the holding transistor 33 and the shorting transistor 23 are rendered non-conductive.

Therefore, here, the fan motor 3 continues to be driven only while the contact 11 is closed, that is, while the control switch 17 supplying power to the relay 43 is conductive, and exhaust air is sent out and the aircraft body is cooled by so-called post-purge.

Incidentally, even in the event of a misfire, the post purge will be carried out automatically as long as the gas switch 2 is closed.

As described above, the combustion machine control device according to the present invention has the following features:
A post-purge driver is connected after the stage of the control switch, which is time-controlled in response to flame detection, and its contacts are connected in parallel to the control switch and fan motor power switch, so the control switch does not have to be turned on when combustion is stopped. The fan motor can be deactivated after a certain period of time has elapsed, and the fan motor can continue to be driven during this period, and a post-purge circuit can be configured by simply adding a driver and its contacts.

[Brief explanation of drawings]

The figure is an electrical circuit diagram of a control device for a combustion machine according to the present invention. 2...Kotuku switch, 3...Fan motor, 11
...Relay contact for post purge, 16...Timer circuit, 17...Control switch, 23...Short circuit transistor, 25...Drive circuit, 35...Flame detection circuit, 36
...Flame detection line, 43...Post purge relay.

Claims (1)

[Claims] 1 Connect the fan motor, ignition device, solenoid valve for fuel supply to the combustor, and control circuit to the commercial power source via a power switch that works with the power switch, and connect the contacts of the post-purge driver in parallel to the power switch. The control circuit includes a flame detection circuit that detects the flame of the combustor and outputs a flame detection signal, and a flame detection circuit that continues to operate when the flame detection signal arrives and deactivates after a certain period of time when there is no flame detection signal. a control switch;
It is equipped with a drive circuit that controls the driver of the ignition device and the solenoid valve, and a post-purge driver that provides a pseudo flame detection signal to the flame detection circuit during post-purge, and is connected to the flame detection circuit via the control switch. A combustion machine control device characterized by connecting a circuit and a post-purge drive body.