JPS6034011B2 - Burner control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a highly safe burner control device.

A conventional burner control device of this type is disclosed in Japanese Patent Application Laid-Open No. 48-3152.
As disclosed in the publication, it has a pre-purge function that operates only the blower prior to combustion, and supplies fuel after removing combustible materials remaining in the combustion chamber from the combustion chamber to cause combustion. .

However, since the burner control device described above is configured to energize the control relay of the fuel supply valve with the output of a time limit circuit having a switching element that operates the fuel supply solenoid valve with a delay from the start of operation of the blower, the time limit circuit If a short-circuit failure occurs in the switching element, the control relay is energized by the switching element at the same time as the blower starts operating, causing the problem that fuel is supplied from the beginning and pre-purge cannot be performed. SUMMARY OF THE INVENTION An object of the present invention is to provide a burner control device that can operate safely even if a short-circuit failure occurs in the switching element in the time limit circuit that controls the fuel supply device.

An embodiment of the present invention will be described below with reference to FIG.

1 is a DC power supply circuit that converts commercial AC voltage to DC low voltage, and includes a step-down transformer T, a full-wave rectifier ○, and a smoothing capacitor C.
It consists of

S is a programmer full junction circuit in which the gate G is connected to the first bleeder circuit 2, and the anode A is connected to the second bleeder circuit via the first diode D in the forward direction.
The relationship between the first bleeder circuit 2 and the second bleeder circuit 3 is set so that the relationship between the first bleeder circuit 2 and the second bleeder circuit 3 is greater than poison so that the transistor (hereinafter referred to as PUT) is always maintained in a non-conducting state. 4 is the frame.

This is a flame detection circuit that detects the presence of flame using a flame detection relay IK that is energized by the output when there is no flame and deenergized by the output when there is flame. There is. C, is a capacitor that is charged to raise the anode potential of PUT (S) higher than the gate potential when no flame is present and conduct the PUT, and is connected to the anode A via two resistors r6 and r7. . Tr is a switching transistor as a switching element to which a base current is applied through a resistor r9 when the PUT(S) is conductive, and is connected to both ends of the capacitor C through a resistor r6. 5 is a discharge circuit that discharges the charge of the capacitor C to the transistor Tr when the switching transistor Tr is conductive; 2K is a control relay inserted in the discharge circuit 5, which is energized by the discharge current and self-maintained; , and is deenergized if it is not ignited by the igniter IG within the discharge time.

D2 is a second reverse diode inserted into the electric circuit 5, I
K3 is the two-terminal contact of the flame detection relay IK, and the relay I
2K3, which switches from the b side to the a side when K is energized, is the control relay 2.
This is a two-terminal short point for self-holding of K, and it is designed to switch from side B to side A when energized. Further, the two-terminal contacts IK32K3 of both the relays IK and 2K are interconnected and connected to the discharge circuit 5. That is, connect the a side of the contact IK3 of the flame detection relay IK to the b side of the contact 2K3 of the control relay 2K via the current limiting resistor r5, and similarly connect the b side of the contact IK3 to the a side of the contact 2K3 with a short-circuit wire. It is connected. S
W is a start switch, TH is a normally closed hot water thermostat that is opened when the water temperature in the hot water tank reaches a predetermined temperature, and 6 is a burner control circuit controlled by both relays IK and 2K. It consists of a blower BM to supply fuel, a solenoid valve SV as a fuel supply device to supply fuel, an igniter IG, etc., each of which is a contact point IK of a flame detection relay IK.
,,IK2, and control relay 2K contacts 2K,,2K2
It is controlled by opening and closing. The configuration of the present invention is as described above, and the operation will be explained next.

First, to explain the normal operating state, a constant DC voltage is generated at the output terminals P, P of the DC power supply circuit 1. When the start switch SW is turned on at the core, the flame detection circuit 4 confirms the absence of flame and outputs an absence output, which energizes the flame detection relay IK and connects the two contacts I of the burner control circuit 6.
K,, IK2 is closed, the blower BM that supplies combustion air and the igniter IG are energized, and the blower Isono M drives out the residual gas in the combustion chamber to perform a so-called pre-purge, and the igniter IG continuously discharges sparks. is carried out, and if fuel is supplied, it will be ready for ignition. Further, the two-terminal contact IK3 of the flame detection relay IK is also switched to the b side. On the other hand, when the start switch SW is turned on, the two bleeder circuits 2 and 3 of PUT(S) are set to harm>poison, so the gate potential is higher than the anode potential, and the PUT(S) is in a non-conducting state.

Then, the direct current flows from the a side of the two-terminal contact of the flame detection relay IK → the current limiting resistor → the b of the two-terminal contact 2K3 of the control relay 2K.
side → control relay 2K → resistor r6 → capacitor C, and the capacitor C is charged.

Here, the switching transistor Tr is PUT(S)
is in a non-conducting state and is not conducting, and therefore, the control relay 2K is not energized only by the current that charges the capacitor C through the current limiting resistor. and capacitor C
, as the charging progresses and its potential rises, the anode potential of PUT(S) rises through the resistor r7, and when it becomes higher than the gate potential, PUT becomes conductive, thereby applying a base current to the switching transistor Tr. be adapted.

Then, the charge of the capacitor C is transferred to the discharge circuit 5, that is, the second
It is discharged to the control relay 2K and the switching transistor Tr through the diode D2. The control relay 2K is energized by the weight of this discharge current and the DC current from the DC power supply 1, and the two contacts 2K, 2K2 of the burner control circuit 6 are closed, and the fuel supply solenoid valve SV is opened, and the oil or gas Fuel is supplied, and since spark discharge has been performed in advance by the igniter IG, the fuel is ignited and combustion begins. When combustion starts, the flame rod detects the flame and the flame detection circuit 4 operates, and its output deenergizes the flame detection relay IK and closes its contact I.
K,, IK2 is opened, igniter IG stops operating, and blower BM continues to operate even if IK and contact are opened because current is supplied through contact 2K of control relay 2K. do.

Therefore, by energizing the control relay 2K, the two-terminal contact 2K
3 is switched to the b side, and since the flame detection relay IK is energized and the two-terminal contact IK3 is in contact with the a side until ignited, the control relay 2K is no longer supplied with current from the DC power supply 1.

However, since the energization continues while the discharge current of the capacitor C is being applied, the energization is maintained if ignition occurs within this discharge time. That is, when ignited, the flame detection relay IK is deenergized, and when its two-terminal contact IK3 returns to the b side, the current from the DC power source 1 flows to the b side of IK3 and 2K3.
Since the voltage is applied to the control relay 2K through the a side of the control relay 2K, its energization continues. That is, the direct current from the DC power supply 1 passes through the current limiting resistor r5.
A large current is applied without being controlled, and the fox 3 acts as a self-holding contact and continues to energize the control relay 2K to continue the combustion operation. In short, the present invention
It is designed to be ignited by the igniter IG within the discharge time of .

In this way, the flame is extinguished normally, and if the start switch SS is turned off, the control relay 2K is deenergized, and its contact 2
K,,2K2 is opened to stop the operation of blower BM and solenoid valve SV. The two-terminal contact 2K3 also returns from the a side to the b side, completing preparations for the next time. According to this embodiment, even if there is a short-circuit accident in the switching transistor T', safe operation is performed as follows.

If there is a short-circuit failure in the switching transistor Tr for some reason, the current will flow to the a side of the contact IK3 of the flame detection relay IK, the current limiting resistor r5, and the b side of the contact 2K3 of the control relay 2K.
On the other hand, the current flows to the switching transistor Tr via the control relay 2K, and the capacitor C is not charged.

Therefore, the control relay 2K is not energized and fuel is not supplied. In this way, if there is a short-circuit failure in the switching transistor Tr, fuel supply can be prevented.

Furthermore, even if there is a short-circuit failure in PUT(S), the switching transistor Tr is suitable for conducting from the beginning.
Similarly, fuel is not supplied. Furthermore, the device of this embodiment performs safe operation even in the event of an abnormality such as non-arrival, which will be described below.

In the case of non-ignition due to a failure of the igniter, etc. In this case, the operation is the same as during normal operation until the control relay 2K is energized by the discharge current of the capacitor C.

If the capacitor is not ignited for some reason during the discharge time, the potential of the capacitor will drop, and eventually the discharge current will no longer flow through the control relay 2K and it will be deenergized. Therefore, the contact point 2K,
, 2K2 are opened, and the operation of the blower BM and the solenoid valve SV is stopped. At this time, the 2-terminal contact 2K3 returns from the a side to the b side, and the DC current changes from the a side of IK3 → current limiting resistor r5 → b of 2K3
The current flows through the side to the control relay 2K, but as described above, since the current limiting resistance is limited by this, the control relay 2K is not energized again. Also, PUT(S) is the second bleeder circuit 3
Since the holding current is supplied from the resistor r3 through the first diode D, it remains in a conductive state, so the switching transistor Tr also remains conductive, so once the capacitor C is discharged, it will not be charged again. . Therefore, the control relay 2K is not energized again and the burner is maintained in a safe state. 'B} If the flame detection circuit is sending out an ignition signal from the time the start switch is turned on.

In this case, the flame detection relay IK is deenergized and the two-terminal contact IK3 returns to the b side, so the capacitor C is not charged and the control relay 2K is not energized, and the flame detection relay IK is also deactivated. Since the blower BM and igniter IG are also inactive, the burner will not start.

If the fire goes out during 'C' combustion.

If the fire is extinguished for some reason such as running out of fuel during combustion, the flame detection circuit 4 confirms the absence of flame, and the flame detection relay IK is energized by the signal, and its two-terminal contact IK3 is switched to the a side.

However, since the 2K3 contact of the control relay 2K has been switched to the a side, if the IK3 contact is now switched to the a side, no current is supplied to the control relay 2K and it is deenergized.

Therefore, the solenoid valve SV and the blower BM are deactivated and the fuel supply is stopped. [Success] In the event of a power outage or hot water thermostat activation during combustion, this is the same as opening the start switch SW, and the control relay 2K is released from holding, and combustion is immediately stopped.

When the power is re-energized, it operates in the same order as when the start switch SW is turned on. Fig. 2 is another circuit diagram of the present invention, which differs from the circuit shown in Fig. 1 in that the connection order of the two-terminal contacts IK3 and 2K3 of the flame detection relay IK and control relay 2K is upside down. The difference is that the connection point of the second diode D2 of the discharge circuit 5 is different, and other than that, it is the same as in FIG. 1, and the control operation is also the same. As described in detail in the above embodiments, the present invention can prevent fuel from being supplied when a short-circuit failure occurs in a switching element in a time-limited circuit that controls a fuel supply device, and also allows conduction to occur in the switching element. This also applies even if the PUT that provides the output is short-circuited, and furthermore, it can quickly respond and stop combustion even in any of the abnormalities shown in the above-mentioned cases (2) to (3), thereby providing a highly safe control device.

Furthermore, the capacitor that supplies the anode potential to make the PUT conductive is separated from the PUT circuit and is used both for charging to take time for prepurge and for discharging to energize the control relay. Sufficient charge can be ensured to energize the control relay during the pre-purge and ignition operations.

In addition, once the PUT conducts, it becomes self-holding, the switching transistor remains conductive, and the capacitor is prevented from being charged again, and if no flame is detected, the control relay is activated as the capacitor finishes discharging. It can be turned off. Furthermore, since it is not affected by the residual charge of the capacitor, for example, in the case shown in column 'E} above, the PUT becomes non-conducting in an extremely short period of time, and the control relay is also deenergized and the combustion operation is disabled. All are stopped and ready for the next pre-purge operation and re-ignition.

[Brief explanation of the drawing]

Both FIGS. 1 and 2 are electrical circuit diagrams illustrating the burner control device of the present invention, and show different embodiments. S...programmer full union transistor, IK...flame detection relay, C. ...Capacitor, Tr
...Switching transistor, 6...Burner control circuit, 2
K...Control relay, 5...Discharge circuit. Figure 1 Figure 2

Claims (1)

[Claims] 1 The blower is operated by a flame detection relay that is energized by the output of the flame detection circuit when there is no flame, and after a predetermined time from the start of operation of the blower, the fuel supply device is activated by the control relay and the ignition is performed at the same time. In the burner control device, the control relay and the programmable union transistor (hereinafter referred to as PUT) are used to cause a dynamic flame to ignite, and when a combustion state is achieved by the ignition, to continue the operation of the fuel supply device by the output of the flame detection circuit. ) are connected in series, and the flame detection relay and the control relay are each provided with a two-terminal contact that switches from side B to side A when energized. Among the terminal contacts, the a side of the two-terminal contact of the flame detection relay and the b side of the two-terminal contact of the control relay are connected via a current limiting resistor, and the b side of the two-terminal contact of the flame detection relay is connected to the b side of the two-terminal contact of the flame detection relay. a of the two-terminal contact of the control relay
The two two-terminal contacts connected in this way are connected in series with the control relay and the switching element, and the gate of the PUT is connected to the first bleeder circuit, and the gate of the PUT is connected to the first bleeder circuit. a second bleeder circuit through a forward diode, a series circuit of a reverse diode and a capacitor connected in parallel with the control relay and the switching element, and a connection between the control relay and the switching element; point above P
A burner control device characterized in that the burner control device is connected to an anode of a UT and a connection point between the reverse direction diode and the capacitor through resistors, respectively.