JPS5969620A - Combustion safety control device - Google Patents

Abstract

PURPOSE:To provide the safety combustion control device which operates such that when heating is required, a burner is ignited automatically and when the burner fails to be ignited correctly, the ignition is shut OFF. CONSTITUTION:A protect relay 1 has such functions that when heating is required, it makes preparations required for the ignition of the burner in accordance with a predetermined sequence and ignites the burner by opening a valve V provided in a fuel gas supply passage while when the burner fails to be ignited, it supplies a signal to a switching circuit 2. The switching circuit 2 is held conductive when it receives the signal from the protect relay 1 and supplies an electric current from a DC power source E1 to a safety switch heater SSH which operates to turn OFF a manually resettable safety switch SSW interposed between the DC power source EL and a load after a lapse of a predetermined time from the time when it is energized so that all the operation of the device are stopped.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a combustion safety control device that automatically ignites a burner when a heat request occurs, and shuts off the burner if it is not ignited normally. It is.

Combustion safety control devices of this type having various circuit configurations have been developed, and devices with a high fail-safe quality Q that always operate safely even in the event of a failure of a circuit element have also been provided. However, if one end of the pulp for fuel control controlled by this combustion safety control device is accidentally grounded (ground fault), the contact inserted between this pulp and the AC power source A dangerous situation may occur in which the pulp opens even though the pulp is open.

This invention was made to eliminate the drawbacks of the conventional ones as described above, and the pulp does not open even if one end of the pulp is grounded, and the ignition sequence starts in this state. It is an object of the present invention to provide a highly safe combustion safety control device that sometimes performs a shut-off operation.

Next, an embodiment of the present invention will be described with reference to the drawings. In FIG. 1, El denotes a DC power supply, and 1 denotes a protect relay that performs a predetermined operation upon receiving current from the DC power supply E1. When a heat request occurs, this protect relay 1 performs the preparatory operations necessary for ignition according to a preset sequence, and then opens the valve V provided in the thread path that supplies fuel gas to the burner to ignite. It also has the function of supplying a signal to the switch circuit 2 when 5 ignition fails. The action of opening valve V is caused by relay 1 having contacts 1 and 2.
This is done by operating K.

Further, the switch circuit 2 becomes conductive when receiving the signal supplied from the protection relay 1 when ignition fails,
A suitable safety shutoff means, in this example a safety switch heater 5S.
Supplies current from the HK DC power supply E1. This safety switch heater SSH operates to turn off the manual reset type safety switch SSW inserted between the DC power supply E1 and its load after a certain period of time after energization, thereby stopping all operations. .

Further, one terminal P1 of the valve V is connected to the non-grounded terminal H of the commercial current source E2 via the contact 1, and the other terminal P2 is connected to the grounded terminal G via the contact IK2.
connected via. Therefore, when the relay 1K is operated and its contacts IK1.1 and 2 are turned on at the same time, the valve (2) is opened. Further, a series circuit consisting of a diode D1 and a resistor R1 is connected to contact 1 in parallel with contact 2,
A light emitting diode of a photocoupler PC is connected so as to be antiparallel to this diode D1. The phototransistor of this photocoupler PC supplies a ground fault detection signal to the switch circuit 2 via the inverter 3 when the phototransistor receives the light from the light emitting diode and becomes conductive. When the switch circuit 2 receives the ground fault detection signal, it turns on in the same way as when it receives the ignition failure signal from the protect relay 1, thereby causing the safety switch heater SSH and the safety switch SSW to shut off. Be done.

Now, terminals H and G are correctly connected to the non-grounded side and the grounded side of AC power source E2, and terminals P1. P
Assume a normal condition with no ground fault in 2 (4). In this state, if contacts IK1 and 1 to 2 are off, no current will flow through valve V and valve V will not operate. Also, □ on contact 1.

As long as 1 and 2 are off, no current will flow through the bulb V even if a ground fault occurs on either side of the terminal P1 or P2.

However, if terminal G is connected to the non-grounded side of AC power supply E2, if a ground fault occurs on the terminal P1 side of valve V, even if contact IK1.1 and 2 are off, the positive During the half-wave period, current flows through the resistor R1, diode D1, and the bulb V, and during the negative half-wave period, the current flows through the pulp V, the light-emitting diode of the photocoupler PC, and the resistor R1. As a result, the phototransistor of the photocoupler PC becomes conductive, the output of the inverter 3 is supplied to the switch circuit 2, and the above-mentioned shirt-to-7 operation is performed. Further, if the resistance value of the resistor R1 is appropriately selected, the valve V will not operate with this current.

A similar shutoff operation is also performed when a ground fault occurs on the terminal P2 side.

FIG. 2 shows an example of the circuit configuration of the combustion safety control device of the present invention in more detail, and parts equivalent to those shown in FIG. 1 are designated by the same reference numerals. The power supply current supplied from the AC power supply E2 passes through the safety switch SSW, then passes through the diode D2, the resistors R3 and R4, and the capacitor C.
1 and a Zener diode D3, and then supplied to the flame detection section 4. The flame detector 4 includes a flame detector 5 such as a CdS element that detects ignition of a burner. In the initial state, the resistance value of the flame detector 5 is high, so the transistor Q1 receiving the pace bias through it is on, and the current flowing through the transistor Q1 and the resistor R5 gradually charges the capacitor C2 and increases its terminal voltage. is enhanced. This voltage is divided by a voltage dividing circuit consisting of resistors R6 and R7 and applied to the base of transistor Q2, so transistor Q2 is turned on after a preset period of time, and relay 2K is connected as its load. operates, and the contact 2 switches to 1.

This state continues until the flame detector 5 detects ignition.

When the contact 2 of the relay 2 is switched to the opposite side from the illustrated position, the igniter IC is operated by the current supplied to the contact 2 through the □. At the same time, a series circuit consisting of a diode D4 and a thyristor SCR is connected to the AC power source E2 via the contact 2 and the thyristor SCR. As a result, a voltage is applied between the anode and cathode of the thyristor SCR, and a charging current flows to the capacitor C3 through the resistor R10. When the terminal voltage of the capacitor C3 reaches the discharge starting voltage of the neon lamp 6, the voltage is applied to the capacitor C3 through the resistor R10. A trigger pulse is supplied to the gate of the thyristor SCR through the gate circuit, and the thyristor SCR becomes conductive. The time from when contact 2KL is switched until Cyrisk SCR becomes conductive is the prepurge time. When Cyrisk SCR becomes conductive, the charge stored in capacitor c3 is transferred to the series circuit of resistor R3, relay 1, and diode D5. The current is discharged through the anode of the risk SCR (7), and this discharge current operates the relay 1K. When relay 1K operates, 2
With two contacts 1, 1 and 2 are turned on at the same time, and the pulp V
Operating current is supplied to This pulp V operates to open a passage for supplying fuel to the burner only while current is being supplied, and ignition is attempted by the action of the ignition transformer G, which has already started operating. Note that while the relay 2K is operating, current is supplied to the safety switch heater SSH and the heat generation continues.

Once ignition is successful and a flame is established, transistor Q1 is immediately turned off due to a rapid decrease in the resistance of flame detector 5, and then transistor Q2 is turned off after a short period of time required for capacitor C2 to discharge. Now, relay 2
K becomes inactive. This causes contact 2 to switch to the position shown in the figure, and the safety switch heater SSH is switched to the AC power source E.
It is separated from 2 and stops generating fever. Also capacitor c3
The charge is discharged through resistor R9 and contact 2.

[7 If the fire does not ignite for some reason, (8
) Since the safety switch heater SSH remains in operation during IJL'-2, the safety switch heater SSH continues to generate heat, and after a predetermined time, a shutoff operation is performed to turn off the safety switch SSW.

On the other hand, if the terminals H and G are reversed when connecting to the AC power source E2 and a ground fault has occurred on the terminal P1 or P2 side of the pulp V, the photo The light emitting diode of the coupler PC emits light, the phototransistor becomes conductive, and the inverter 3 outputs a ground fault detection signal. Since the output end of inverter 3 is connected to the gate of thyristor SCR, relay 2K operates and its contact 2
At the moment when is switched to , thyristor SCR becomes conductive,
As in the case of ignition failure, the safety switch S is turned off after a certain period of time.
A shutoff operation is performed in which the SW is turned off.

As described above, according to the present invention, even if one end of the pulp has a ground fault, a situation in which the pulp is accidentally opened due to the connection state of the AC power supply does not occur, and the ground fault does not occur. High safety is also guaranteed. Even if the combustion safety control device's ground side is initially connected correctly to the AC power source's ground side, the connection may be reversed during maintenance, or the polarity may be reversed due to construction on the power transmission line side. Therefore, this invention is extremely useful from the standpoint of ensuring safety.

In addition, although the above embodiment shows the case where the AC power supply is single phase, it is also possible to use a three-phase AC V-connection or irregular V-connection.

□ can be similarly applied in cases such as △ wiring.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing the configuration of a combustion safety control device according to an embodiment of the present invention, and FIG. 2 is a circuit diagram specifically showing the protection relay portion thereof. 1...Protect relay, 2...Switch circuit, 3
...Inverter, 4...Flame detection circuit, 5...Flame detector, El...DC power supply, E2...AC power supply,
SSH... Safety switch heater, SSW... Safety switch, ■... Pulp, IK, 2K... Relay, P
C...Photocabra.

Claims (1)

[Claims] After the heat demand is generated, the necessary preparatory operations for ignition are performed according to a predetermined sequence, and then the pulp installed in the thread path that supplies fuel to the burner is opened to perform the ignition operation, and if one ignition fails, In the combustion safety control device configured to perform a shut-off operation, normally open contacts of a relay operated by a signal at the start of ignition are inserted between both ends of the pulp and both ends of the AC power source, and
A series circuit consisting of a photocoupler's light emitting element and a resistor is connected in parallel with one normally open contact, and the output signal taken from the photocoupler's light receiving element side is used to perform the same shutoff operation as the ignition failure. A combustion safety control device characterized by comprising: