JPS6323449B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a control device for a combustion machine using gas, etc., and in particular, it is designed to automatically perform post purge in order to cool the machine body and send out exhaust gas. .

This type of device performs flame detection control, so if the fan motor is driven together with the ignition device and fuel supply device, the fan motor must be operated individually because the fuel supply is stopped during post purge. Needs to be driven. Therefore, in the past, a dedicated operation knob was provided for post-purge, or the post-purge circuit was made independent from the flame detection control circuit, which caused difficulties in circuit design and the need for multiple circuit elements. It was a waste.

The present invention has been made in view of the above points, and embodiments thereof will be described below with reference to the drawings.

1 is a commercial power supply, and the first switch 2, which is linked to the switch that opens and closes the gas supply path, is connected in series.
A fan motor 3 and a power transformer 4 are connected in parallel in order to supply combustion air to the burner and to simultaneously release combustion exhaust into the circulation room air, and a power transformer 4 is connected in parallel to the rear of the first switch 2, and an ignition relay is connected to the rear of this transformer. Ignition devices 6 are connected in parallel via contacts 5. Reference numeral 7 denotes a gas supply relay contact which is connected in series to the first control switch 2 at the rear stage of the ignition device 6, and an ignition solenoid valve 8 for ignition and a main solenoid valve 9 for the main burner are connected in parallel to the power supply 1. There is. 10 is a detection operation 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 first control switch 2;
Reference numeral 12 denotes a flame detector provided in the secondary winding of the power transformer 4 to detect 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 which outputs a low potential due to an increase in the charging level of the first control switch 18.
and two comparators 21 that output a high potential due to an increase in the charging level of the second capacitor 20, 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. Note that the charging time for inverting the first comparator 19 of the first capacitor 18 is about 30 seconds at the longest, and the charging time for inverting the second comparator 21 of the second capacitor 20 is about 5 seconds at the shortest. There is.

Further, 23 is a shorting 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 its base connected to the output terminal of the third comparator 27 and has the 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
Ignition relay 28 until 7 is reversed to low potential output
and the gas supply relay 31, and when the holding transistor 33 is turned on, the gas supply relay 3 is activated.
Operate only 1. 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 third capacitor input terminal of the third comparator 27 via a fourth diode 42.

Therefore, when detecting flame, the first and second FETs 37 and 38
When the relay transistor 40 becomes conductive and the flame detection transistor 41 becomes non-conductive,
The holding transistor 33 is conductive, and the third comparator 2
7 is the fourth capacitor 26 in addition to the charging level of the third capacitor 26.
A high potential is inputted through the diode 42 and immediately reversed, and a low potential is output to the ignition transistor 2.
9 is made non-conductive.

43 is a post-purge circuit that continues to drive the fan motor 3 for a certain period of time for so-called post-purge even if the gas supply by the gas supply is cut off. A fourth comparator 47 outputs a high potential as the charge level rises and outputs a low potential after discharging as a differential timer, and a post-purge relay 48 whose base is connected to the output terminal of this comparator and whose collector is connected to the fourth comparator 47. A post-purge transistor 49 connected in series and a dividing resistor 45 are connected in parallel to suppress a sudden drop in the reference voltage when the power is turned off, and to prevent the fourth comparator 47 from repeating inversion. and a reference voltage capacitor 50. Reference numeral 51 denotes a charging path branch-connected from the collector of the ignition transistor 29 to the fourth capacitor 46, in which two diodes are connected in series and a second switch 52 connected to the switch is inserted and connected.

Therefore, the post-purge transistor 49 becomes conductive when the fourth comparator 47 outputs a high potential, and becomes non-conductive when the fourth capacitor 46 is discharged for a certain period of time and changes to a low potential output. However, even when the switch 52 is closed, the fourth comparator 47 remains at a low potential output if the ignition transistor 29 is conductive because the fourth capacitor 46 is short-circuited. That is, the post-purge relay 48 is not driven during the ignition operation before the ignition burner is normally combusted, and the contact 11 remains open.

The charging time of the fourth capacitor 46 for inverting the fourth comparator 47 to a high potential output is short because the charging resistance is small, and the discharging time for returning the fourth comparator 47 to a low potential is long, about 60 seconds. .

Further, 53 is a forced power supply line that connects the normally closed contact 54 of the second switch 52 and the base of the relay transistor 40, and when power is supplied, the relay transistor 40 is made conductive and the flame detection transistor 41 is made non-conductive and short-circuited. The transistor 23 is turned on.

Furthermore, 55... are the first to fourth capacitors 18,
20, 26, 46 and a diode for assisting discharge of the reference voltage capacitor 50.

Next, the operation will be described. First, the switch is opened to supply gas, and the first and second switches 2 and 52 are closed in conjunction with each other. Then, the fan motor 3 is driven to perform a so-called prepurge inside the combustor. During this time, the first comparator 19 outputs a high potential, but the second comparator 21 outputs a low potential, so the control switch 17 is non-conductive, and each relay 28, 31,
48 is not working. This pre-purge time is approximately 5 seconds during which the second comparator 21 is reversed to a high potential output, and when the control switch 17 is made conductive due to the reversal of the second comparator 21, the ignition reloo 28 and the supply gas relay 31 are activated. Power is supplied through the ignition transistor 29, and ignition operation is started. When the ignition burner is ignited and burned by the ignition device 6 by closing the ignition relay contact 5 and the gas supply relay contact 7, the detection body 12 detects the flame and outputs it to the detection line 36. , the second FETs 37 and 38 are made non-conductive. Then, the holding transistor 33 becomes conductive.
The LED 34 lights up and the gas supply relay 3
1 continues to operate, and the flame detection transistor 41
becomes non-conductive, and the third comparator 27 is immediately reversed to a low potential output, causing the ignition transistor 29 to become non-conductive and the short-circuiting transistor 23 to become conductive. The ignition combustion of this ignition burner is for a short time (approximately 30
(within seconds), the charging capacity of the first capacitor 18 is small, so the first comparator 19 is not inverted to a low potential output, and the first and second comparators 19,
The high potential output of 21 causes control switch 17 to remain conductive. However, the ignition combustion was delayed and the first and second
When the 2FETs 37 and 38 continue to conduct, the charging level of the first capacitor 18 increases and about 30 seconds later, the first comparator 19 outputs a low potential, making the control switch 17 non-conductive and sending the signal to the drive circuit 25. 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 capacitor 26 will be charged approximately 40 seconds after the third capacitor 26 is charged.
The comparator 27 is made to output a low potential, the ignition transistor 29 is made non-conductive, and the operation of the ignition relay 28 and the supply gas relay 31 is stopped. 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.

Thus, when the ignition transistor 29 becomes non-conductive due to ignition combustion of the ignition burner, the fourth capacitor 46 immediately starts charging via the charging path 51, and the increase in potential causes the fourth comparator 47 to output a high potential. The post-purge transistor 49 is made conductive only after it is reversed, and the post-purge relay 4 is turned on.
8 to close its contact 11. Here, the post-purge relay 48 is the ignition relay 2
Since it operates after relay 8 stops operating, relay 28, 3
1, 48 is any 2 during the operation leading to normal combustion.
Only these relays operate, reducing the power capacity of the power transformer 4.

Then, while the ignition burner is burning, the main solenoid valve 9 is also opened and closed by opening and closing the detection operation switch 10, so that the main burner is ignited and burnt by the ignition burner at an appropriate time.
Furthermore, due to the non-conduction of the ignition transistor 29, the ignition relay 28 is also deactivated, opening the contact 5, and the ignition device 6 is also stopped. The circuit constants are determined in .

In addition, when the burner misfires due to blowout during combustion, the first and second FETs 37 and 38 become conductive, so the holding transistor 33 and the shorting transistor 23
becomes non-conducting, the gas supply relay 31 immediately deactivates and opens its contacts 7, stopping the gas supply, and the first
Capacitor 18 begins charging. And the first
Comparator 19 is inverted to a low potential output and control switch 17 is rendered non-conductive. In addition, overheating prevention switch 24
When the engine opens, the same operation as in the case of misfire occurs.

Next, when the burner is closed after the prescribed burner combustion and the first and second burner switches 2, 25 are opened, the burner is extinguished by stopping the gas supply, and the post-purge circuit 43 receives the post-purge start signal. In response to this, the fourth capacitor 46 starts discharging and operates as a differential timer, the fourth comparator 47 maintains a high potential output for about 60 seconds, and the post-purge relay 48 keeps its contact 11 closed. The fan motor 3 continues to drive to perform a so-called post purge. During this time, the control switch 17 must be conductive in order to supply power to the post-purge relay 48, but by switching the second switch 52 to the normally closed contact 54 side, power is supplied from the forced power supply path 53 to the relay transistor 40. The flame detection transistor 41 becomes non-conductive and the shorting transistor 23 becomes conductive, maintaining the first comparator 19 at a high potential output and maintaining the control switch 17 conductive. That is,
By switching the second control switch 52, a simulated flame detection signal is applied to the control switch 17. During this time, the third diode 39 is cutting off the side path. Note that this post-purge is also performed in the same way when a misfire occurs and the first capacitor 18 starts charging and the user closes the pot before the first comparator 19 is inverted to a low potential output. If it has already been reversed, the fan motor 3 is
is being driven, so this period is called post purge.

Note that the reference voltage capacitor 50 is connected when the post-purge time ends, that is, the fourth comparator 47 outputs a low potential, and the post-purge relay contact 11 opens.
This suppresses a sudden drop in the reference voltage of the fourth comparator 47 when the power is suddenly cut off. That is, when this reference voltage drops more rapidly than the comparison voltage by the fourth capacitor 46, the fourth comparator 47 reverts to a high potential output, and the post-purge relay 48 is reactivated by the residual charge in the circuit. This is because it rarely occurs.

As described above, the combustion machine control device according to the present invention has the following features:
The second switch, which is linked to the switch operation, provides a post-purge start signal to the post-purge circuit when the switch is closed, and also provides a simulated flame detection signal to the control switch, so the post-purge circuit can be integrated into the rear stage of the control switch. It has the advantage that it can be operated even if it is assembled, and that the circuit configuration can be simplified. Also, when the switch of the second switch is opened, the capacitor for the differential timer of the post-purge circuit is charged and the post-purge relay contact is activated, and when the switch is closed, the control switch is connected from the closing contact of the second switch. Since a similar flame detection signal is provided, post-purging can be reliably performed simply by switching the second switch, that is, opening and closing the switch.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram showing the relationship between FIGS. 2 to 4;
Figure 2 is an electric circuit diagram of the fan motor, ignition device and fuel supply section, Figure 3 is an electric circuit diagram of the control switch section and drive circuit, and Figure 4 is an electric circuit diagram of the flame detection circuit and post purge circuit. . 2...1st control switch, 3...fan motor,
DESCRIPTION OF SYMBOLS 11... Relay contact for post purge, 17... Control switch, 35... Flame detection circuit, 40... Transistor for flame detection, 43... Post purge circuit, 46... Fourth
Capacitor, 48... Post purge relay, 51
...Charging path, 52...Second power switch, 53...Forced power supply path, 54...Normally closed contact.

Claims (1)

[Claims] 1 Connect the solenoid valve that controls the supply of fuel to the combustor through the first switch that is linked to the opening/closing operation of the switch to the commercial power source, the ignition device of the combustor, and the fan motor that sends out combustion exhaust, etc. It also includes a main circuit in which the contacts of a post-purge relay are connected in parallel to the first control switch, and a control circuit that controls this main circuit and is operated by a DC power supply. A drive circuit that controls the valve, a flame detection circuit that provides a signal to a timer circuit that maintains the operation of the drive circuit and control switch, and a flame detection circuit that operates for a certain period of time after the post-purge relay is closed to maintain its contact point constant. A post-purge circuit that closes for a certain period of time and a second switch that applies a post-purge start signal to the post-purge circuit in conjunction with the shut-off closing operation and operates the post-purge circuit for a certain period of time are connected, and the timer The circuit is connected to the DC power supply side of the control switch so that the control switch remains activated for a predetermined period of time after the opening operation and while a signal from the flame detection circuit activated by the presence of flame or a pseudo flame detection signal is applied. A combustion machine control device that is connected to.