JPS5842765Y2 - Combustion control device - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a combustion control device for gas appliances and the like.

Generally, in most cases, gas appliances are controlled by turning on a switch to activate a relay in response to a signal from a pre-purge circuit or a pre-check circuit, and the activation of this relay energizes the burner circuit and ignites the pilot burner.

Next, the ignition of the burner is detected by a flame detection circuit, the ignition device is stopped, and the main solenoid valve is opened to supply gas to the main burner.

When the switch is opened, the above two relays stop operating and combustion is stopped.

However, with conventional burners, if the switch is opened once and then closed again, if the interval is too short, raw gas will gush out from the main burner, resulting in a dangerous situation such as an explosion.

This is because the power supply voltage drops slowly even when the switch is opened, and the burner combustion flame does not stop immediately even when the gas supply is cut off, but there is a slight time delay.

That is, when the burner is closed again, the main solenoid valve is in a state where it can be energized while the burner combustion flame is present, and the relay that controls the energization of the burner circuit can also be operated.

The present invention solves the above-mentioned problems by adding a simple circuit configuration, and will be specifically explained below based on an embodiment shown in the drawings.

1 is a burner circuit connected between the primary power supply of the transformer 2 via a normally open contact 4 of a relay 3, which will be described later.
A pilot main solenoid valve 5, an ignition device 8 such as an igniter on the normally closed contact side, and a main solenoid valve 9 on the normally open contact side are arranged in parallel via a changeover switch 7 of a relay 6, which will be described later. It is.

10 is a rectifier, and 11 is a switch.

Reference numeral 12 denotes a flame detection circuit, which detects the combustion flame when the burner ignites and sends a flame detection signal, and the signal current increases the base potential of the transistor Q1 to make it conductive, thereby activating the relay 6.

Reference numeral 13 denotes a circuit that issues a combustion permission signal such as a pre-purge circuit or a pre-check circuit. For example, when the circuit 13 is used as a pre-purge circuit, the pre-check signal is activated when a fan motor (not shown) is driven for a certain period of time, or when the circuit 13 is used as a pre-check circuit. The above signal may be sent when the process is completed.

Q4 is a switching element that becomes conductive upon receiving this signal, and Q3 is a transistor that becomes conductive when element Q4 becomes conductive to operate the relay 3.

R15 is a discharging resistor, and C1 is a capacitor that exhibits the function described later. The capacitor C1 is charged in a very short time when the switch 11 is turned on.

R12 is a voltage dividing resistor.

The capacitor C1 and the resistor R14 are connected to the base of the transistor Q4 via a diode D2 in the opposite direction to the resistor R11.

The present invention has the above-described configuration, and when the switch 11 is turned on, the pre-check circuit 13 is activated to perform a pre-check before combustion, and if there is no abnormality in the circuit after the set time is over, a combustion permission signal is sent to the switch element Q4. Switch element Q4 becomes conductive.

If the switching element Q4 becomes conductive, the transistor Q3
conducts, so relay 3 operates and contacts 4 are closed.

Therefore, the main solenoid valve 5 is energized and opened, gas is supplied to the pilot burner, and the ignition device is activated to ignite the pilot burner.

When the burner is ignited, a flame detection signal is sent from the flame detection circuit 12, and the transistor Q1 becomes conductive, activating the relay 6, which switches the switching contact 7 to the main solenoid valve 9 side. The burner burns.

Then, when switch 11 is opened to stop combustion, the charge on capacitor C1 is changed to resistance R15 - resistance R12 - resistance R1.
1 - is discharged through the path of the diode D2, and a reverse voltage appears at the base of the switching element Q4.
is immediately cut off, and accordingly, transistor Q3 is also cut off, and relay 3 immediately stops operating.

Therefore, even if switch 11 is turned on again while the combustion flame remains in the burner, switch element Q4 will remain in circuit 1.
Unless a new combustion permission signal is received from No. 3, conduction will not occur, and the above-mentioned release of raw gas and accompanying explosion can be prevented.

In other words, in the present invention, if the circuit 13 is used as a pre-check circuit, the pre-check operation will always start no matter how quickly the switch 11 is turned on again, and if the circuit 13 is used as the pre-purge circuit, the gas appliance will always start with the pre-purge. This can greatly contribute to safety.

[Brief explanation of drawings]

The drawing is a circuit diagram showing an embodiment of the present invention. 1... Burner circuit, 3... Relay, 4
...Normally open contact, 6...Relay, 7...
...Switching contact, 8...Ignition device, 9...
...Main solenoid valve, 11...Switch, 13...
...Circuit, Q4...Switch element.

Claims (1)

[Scope of utility model registration request] After the switch is turned on, there is a switch element that conducts in response to a combustion permission signal from the circuit, a relay that operates when this switch element conducts and switches the normally open contact in series with the burner circuit, and a relay that operates in response to a flame detection signal to switch the burner circuit. In a relay that switches the switching contact of the circuit from a normally closed igniter side contact to a normally open main solenoid valve side contact, a reverse voltage is applied to the switch element at the same time as the switch is opened to shut it off,
A combustion control device characterized in that the former relay is cut off before the latter relay is cut off.