JPH08233256A - Safety device for combustion apparatus - Google Patents

Abstract

PURPOSE: To prevent a raw gas from being discharged when a mis-firing happens during the usage of a combustion apparatus, and when a combustion is not started at the time of hot start. CONSTITUTION: A MOSFET 3 which provides a switching operation is inserted and connected between a thermal generating element 1 which is heated by a burner flame and generates a thermoelectromotive force, and a solenoid safety valve 2 which control the opening/closing of a gas feeding passage. Then, the MOSFET 3 is controlled based on an output signal of a flame-detecting circuit D which detects the presence/absence of flames.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a safety device for a combustion appliance which prevents release of raw gas in the event of misfire during hot start or misfire during the start.

[0002]

2. Description of the Related Art A conventional safety device for a combustion appliance of this type is
It consists of a thermoelectric generator that is heated by a burner flame to generate thermoelectromotive force and an electromagnetic safety valve that controls the opening and closing of the gas supply passage.When a flame is formed by ignition operation, the thermoelectric generator heats the thermoelectric generator by the burner flame. An electromotive force is generated, an exciting current is sent to the electromagnetic safety valve, and at the same time as the ignition operation, a quick current keeps the electromagnetic safety valve that is in the open state as it is, and if the ignition fails or a misfire occurs midway, heat is generated. It is widely used that the electromagnetic safety valve is closed after waiting for the thermoelectromotive force of the power generation element to drop to the release voltage of the electromagnetic safety valve.

[0003]

However, in the above-described conventional safety device for a combustion appliance, even if the flame disappears when the thermoelectric generator is in a heated state, the thermoelectromotive force immediately causes the electromagnetic safety valve to separate due to thermal inertia. Since it does not drop to the voltage, raw gas is released for a while. Also, if you are using a combustion instrument and stop using it once, and then immediately after that, if you re-ignite it for reuse, or if you do a so-called hot start, the thermoelectric generator will not immediately cool, so its thermoelectromotive force will cause electromagnetic safety valve Even if the ignition fails due to the re-ignition operation and no flame is formed, the electromagnetic safety valve is kept open for a while, so that raw gas is released.

In view of the above problems, the present invention determines that there is no flame by a flame detection circuit that inserts and connects a switching element such as a MOSFET between the thermoelectric generator and the electromagnetic safety valve and detects the presence or absence of flame. In that case, the switching element is immediately turned off, the exciting current flowing from the thermoelectric generator element to the electromagnetic safety valve is shut off, and the release of raw gas is caused when misfire occurs during hot start of the combustion equipment and during misfire during use. It is an object of the present invention to provide a safety device for combustion appliances that can be prevented.

[0005]

In order to achieve the above object, a safety device for a burner according to the present invention comprises a thermoelectric generator 1 which is heated by a burner flame to generate thermoelectromotive force and a gas supply passage opening / closing control. The switching element 3 such as a MOSFET that performs a switching operation is inserted and connected between the electromagnetic safety valve 2 and the electromagnetic safety valve 2, and the switching element 3 is controlled based on the output signal of the flame detection circuit D that detects the presence or absence of flame.

[0006]

In the safety device for a combustion appliance configured as described above, the switching element 3 is turned on with ignition operation, a flame is formed in the burner, the thermoelectric generator element 1 is heated by the burner flame, and thermoelectromotive force is generated. An exciting current flows to the electromagnetic safety valve 2 through the switching element 3 and holds the electromagnetic safety valve 2 in the open state.

When the flame disappears for some reason during combustion, the flame detection circuit D outputs a flameless output signal, the switching element 3 is turned off, and the exciting current flowing through the electromagnetic safety valve 2 is immediately cut off. The electromagnetic safety valve 2 is closed to close the gas supply passage to prevent the release of raw gas.

When the combustion device is hot-started, that is, when the combustion device is in use and once stopped, and immediately after that the ignition operation is performed again, the thermoelectric generator 1 continues to generate thermoelectromotive force due to thermal inertia, In some cases, a thermoelectromotive force that is equal to or higher than the release voltage of the electromagnetic safety valve 2 is generated. Therefore, when the re-ignition operation is performed and ignition fails and flame is not formed in the burner, the flame detection circuit outputs an output signal without flame, the switching element 3 is turned off, and the thermoelectric generator element 1 switches to the electromagnetic safety valve 2. The flowing exciting current is cut off and the electromagnetic safety valve 2 is closed to prevent release of raw gas.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of a safety device for a combustion appliance according to the present invention will be described below with reference to FIGS.

FIG. 1 is a combustion control circuit for a combustion appliance, where A is a control circuit, B is a safety device circuit connected to an output terminal TCC of the control circuit A, and C is a solenoid valve 2 of a safety device circuit B and a control circuit A. I ₁ → I ₂ → I ₃ from the time of ignition operation by the control signal output from the MG ₁ , MG ₂ and MG ₃ terminals of
An electromagnetic safety valve drive circuit in which an exciting current is supplied while changing the order of (I ₁ > I ₂ > I ₃ ), and D is a flame current F
A flame detection circuit for detecting the presence / absence of flame detected by L, is connected to the output terminal FGO of the control circuit A, and the output signal of the flame detection circuit D with or without flame is the input terminal FGI of the control circuit A. Connected so that you can enter into. E is an ignition circuit that blows sparks by an igniter during ignition operation, and is connected to the IG terminal of the control circuit A.

F inputs an operation signal of an ignition switch SW ₁ which is operated in accordance with an ignition operation to an input terminal PSW of a control circuit A, and G is a water flow switch which is activated by the presence or absence of the water flow when the water supply is started by the ignition operation. The operation signal of SW ₂ is connected so that it can be input to the input terminal WFS of the control circuit A. Further, the voltage monitoring circuit H and the battery replacement lamp circuit I are connected to the VD terminal and the LED terminal of the control circuit A.

The safety device circuit B includes an electromagnetic safety valve 2 for controlling opening / closing of a gas supply passage, a secondary thermocouple 4 heated by abnormal combustion of a burner, and a MOS for turning on / off an exciting current.
FET3 and thermal fuse 5 for preventing heating of combustion equipment,
Further, when the primary thermocouple 1 installed so as to face the normal combustion flame of the burner is connected in series in order, the polarity of the secondary thermocouple 4 is opposite to that of the primary thermocouple 1 and is connected, and when the burner abnormally burns The thermoelectromotive force of the primary thermocouple 1 can be canceled and the electromagnetic safety valve 2 can be closed. The gate of the MOSFET 3 is connected to the TCC terminal of the control circuit A, and based on the output signal of the flame detection circuit D depending on the presence or absence of flame, the MOSFET is turned off through the control circuit A when there is no flame and the primary thermocouple 1
The exciting current flowing from the electromagnetic safety valve 2 is cut off.

The operation of the above embodiment will be described below with reference to the flowchart of FIG. As for the driving operation when using a combustion instrument, when the ignition button is pressed, the ignition switch SW ₁ of the ignition switch circuit F is turned on, and the battery voltage is 1.9.
1.9V is determined by the voltage monitoring circuit H that the voltage is higher than V.
At the following times, the battery replacement lamp circuit I operates via the control circuit A and the battery replacement lamp blinks. In this case, the driving operation can be restarted if the cause is removed by replacing the battery.

When the battery voltage is 1.9 V or more, the water supply is started in response to the pressing operation of the ignition operation button, and the water flow switch SW ₂ of the water flow switch circuit G is turned on when there is a water flow and the switching element 3 Also, the electromagnetic safety valve 2 is turned on, a quick current I ₁ flows from the electromagnetic safety valve drive circuit C, and the igniter of the ignition circuit E blows a spark. Then, one second after the water flow switch SW ₂ is turned on, the quick current flowing to the electromagnetic safety valve ₂ is lowered from I ₁ to I ₂ , and the flame detection circuit D is turned on. And the flame detection circuit D
There turned on, it is determined whether or no flame exists from the on-water flow switch SW ₂ after two seconds, when the flame is not turned off the switching element 3 is turned OFF quick current flowing through the electromagnetic safety valve 2. As a result, even at the time of hot start, the exciting current from the thermoelectric generator 1 generated by thermal inertia is shut off, the electromagnetic safety valve 2 is closed, and the release of raw gas is stopped.

When there is a flame, 6 seconds after the water flow switch SW ₂ is turned on, the quick current flowing through the electromagnetic safety valve 2 is further reduced from I ₂ to I ₃ , and the igniter of the ignition circuit E is also turned off. The quick current I ₃ flowing in the electromagnetic safety valve 2 is turned off 12 seconds after the water flow switch SW ₂ is turned on, and at this time point, the primary thermocouple 1 of the safety device circuit B is heated and a large exciting current is flowing in the electromagnetic safety valve.
Even if the quick current becomes 0, it remains open. Then, if there is no abnormality, the combustion is continued, and if the flame disappears for some reason, the flame detection circuit D detects this and turns off the switching element 3. As a result, the exciting current is cut off and the electromagnetic safety valve is closed to prevent the release of raw gas.

For some reason, the burning appliance overheats,
When the thermal fuse 5 is blown or the secondary thermocouple 4 is heated due to abnormal combustion of the burner to cancel the electromotive force of the primary thermocouple 1, the voltage applied to the electromagnetic safety valve 2 falls below the release voltage and the electromagnetic safety valve 2 To stop the abnormal combustion by closing the gas supply passage. When stopping the use of combustion equipment, the ignition switch turns off when the operation button is pressed,
The switching element 3 is also turned off. Then, the electromagnetic safety valve 2 is closed by the switching element 3, and the water flow switch is also turned off when the water supply is stopped, so that the operation of the combustion appliance is stopped.

[0017]

According to the safety device for a combustion appliance of the present invention described above, a switching element such as a MOSFET that performs a switching operation is inserted and connected between an electromagnetic safety valve and a thermoelectric generator, and a flame detection circuit prevents a flame. If it is judged that the switching element is turned off immediately, the exciting current flowing from the thermoelectric generator element to the electromagnetic safety valve is immediately cut off, and the electromagnetic safety valve can be closed to stop the gas supply. When a misfire at time and a misfire during use occur, it is possible to immediately prevent the release of raw gas, prevent an unpleasant odor of raw gas from being generated, and further improve safety.

[Brief description of drawings]

FIG. 1 is a combustion control circuit of a combustion instrument.

FIG. 2 is a flowchart showing the operation of the combustion appliance.

[Explanation of symbols]

 1 Thermoelectric generator element 2, Electromagnetic safety valve 3 Switching element D Flame detection circuit

Claims (1)

[Claims] 1. An MO that performs a switching operation between a thermoelectric generator (1) that is heated by a burner flame to generate thermoelectromotive force and an electromagnetic safety valve (2) that controls the opening and closing of a gas supply passage.
A switching device (3) such as an SFET is inserted and connected, and the switching device (3) is controlled based on an output signal of a flame detection circuit (D) for detecting the presence or absence of a flame. .