JPH033807Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a semi-automatic gas combustion safety device for heating appliances, and is particularly applicable to conventional gas combustion safety devices in which the ignition switch must be held down until ignition is confirmed. This relates to a semi-automatic combustion safety device that is an improved technology.

[Conventional technology]

In the case of a conventional semi-automatic gas combustion safety device related to a stove as shown in FIG. igniter 2
However, if the user turns on the ignition switch 5 before the thermocouple 3, which detects the presence or absence of a flame, detects the establishment of ignition, the main valve 1 must be closed for safety. Configured to stop combustion. On the other hand, if the thermocouple 3 detects the establishment of a flame, safety has been confirmed, so the main valve 1 continues to open regardless of the ignition switch 5 and enters the combustion state. That is, the user must continue to press the ignition switch 5 until the thermocouple 3 detects the establishment of a flame.

In the conventional configuration described above, especially in the thermocouple which is most commonly used as a flame sensor,
Due to the heat capacity, there is a time delay in flame detection, so if the user returns the ignition switch early, the flame cannot be detected even though the ignition is on, resulting in a safety shutdown. The drawback was that it was difficult to use.

[Summary of the idea]

The present invention was developed in view of these circumstances, and even if the ignition switch is returned to its original position, the main valve continues to open by creating a pseudo-flame state for a certain period of time, and if the thermocouple rises during this period, normal combustion will begin. To provide an easy-to-use semi-automatic combustion safety device configured to enter a safety stop if a thermocouple does not start up during this period, and which has fail-safe properties and improved safety.

[Example of idea]

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

FIG. 1 is a circuit diagram showing an embodiment of a semi-automatic combustion safety device according to the present invention. In the figure, 1 is the main valve, 2 is the igniter, 3 is the thermocouple which is the flame detection means, and the combustion safety device is the third one.
The relationship is as shown in the figure. 4 is the power supply, 5
is the ignition switch. The ignition switch 5 is linked to the switch 6, and when the ignition switch 5 is pressed and closed, the switch 6 is also closed.
If the ignition switch 5 is returned to its original position and opened, the switch 6 will also be opened at the same time. Reference numeral 7 is a rectifier which lowers the AC voltage of the power source 4, which has been stepped down through a transformer, into a DC voltage to supply DC power. Resistors R1 and R connected in series with switch 6
2 is connected to the base of a transistor Q1 which is a switching means, and a capacitor C1 which is a first delay means is provided between this base and a common potential. Furthermore, a capacitor C serving as a second delay means is connected in parallel with the resistors R1 and R2.
2 is provided. 8 is a hold circuit as a comparison hold means which also serves as flame detection, and its inverting input terminal (-) is connected to a resistor R3 and resistors R4 and R5.
A constant voltage value V _ref determined by the ratio of is input, and is connected to the collector of the transistor Q1 via a resistor R6. The non-inverting input terminal (+) of the above hold circuit 8 is connected to the non-inverting input terminal (+) through the resistor R7.
It is connected to the DC power line and one end (+) of the thermo couple 3 is connected, and the other end (-) of the thermo couple 3 is connected to the resistors R3, R4 and the resistor R5.
connected to a potential determined by the ratio of Hold circuit 8
The output of is connected to the base of transistor Q2,
A parallel connection of a relay K1 and a diode D1 is connected to the collector of this transistor Q2. A capacitor C3 and a resistor R8 are connected in parallel to the series connection of the relay K1 and the transistor Q2, and a resistor R9 is further connected in series thereto. The contact K1-1 (switching means) of the above-mentioned relay K1 is arranged so as to select whether to connect the main valve 1 to the power source 4 via the ignition switch 5 or directly to the power source 4. When is not energized, this contact K1-1 is set to the ignition switch side. Note that the voltage of the transformer is configured to be taken out from the movable contact portion of the contact K1-1.

Next, the operation of the present invention configured as described above will be described in a second manner.
The explanation will be given according to the time chart shown in the figure. Note that A is a time chart when there is no ignition, and B is a time chart when ignition occurs. When the user presses the ignition switch 5, an ignition trial is started in which the power source 4 is connected to the main valve 1 and the igniter 2. At the same time, AC power is supplied to the transformer via contact K1-1, so DC power is supplied to the entire circuit, and there is a delay for the time that switch 6 closes and capacitor C1 is charged.
Transistor Q1 turns on after _T1 . When there is no flame, no electromotive force is generated in the thermocouple 3, but at this time the inverting input terminal (-) of the hold circuit 8 determined by the division ratio of the resistors R3, R4, and R5
The input voltage V _ref is the resistor R3, R4, R5, R7
Since the input voltage of the non-inverting input terminal (+) is set to be higher than the input voltage of the non-inverting input terminal (+) determined by However, by turning on the transistor Q1, the input voltage _Vref at the inverting input terminal (-) is forcibly lowered because a bypass circuit passing through the resistor R6 is formed. As a result, the input voltage V _ref at the inverting input terminal (-) of the hold circuit 8 is forcibly lowered than the input voltage at the non-inverting input terminal (+), so even if the thermocouple 3 does not detect a flame, the It becomes a flame state and the output of the hold circuit 8 is
It will turn into HI.

On the other hand, since no DC power is supplied before the ignition switch 5 is pressed, no charge is accumulated in the capacitor C3. When the ignition switch 5 is pressed here, the output of the hold circuit 8 is LO until the delay time T ₁ is reached, so the transistor Q2 is OFF, and during this time the capacitor C3 is determined by the division ratio of the resistors R8 and R9. It will be charged up to the voltage value. When the delay time _T1 elapses and the hold circuit 8 turns HI, the transistor Q2 turns on, so the charge in the capacitor C3 flows through the relay K1, turning the relay K1 on. When the relay K1 is energized, the relay contact K1-1 is switched, and the main valve 1 is kept open regardless of the ignition switch 5. Further, since the AC power source is also connected to the transformer without going through the ignition switch 5, the DC power source continues to be supplied to the entire circuit. Conventionally, when you stop pressing the ignition switch, the thermocouple determines that no flame is detected and immediately closes the main valve. In other words, due to the thermal delay of the thermocouple, even if the flame had actually been established, it would stop, resulting in a wasteful situation. In contrast, in the present invention, the ignition switch 5
Even if you stop pressing , the time it takes for the charge charged in capacitor C2 to discharge through resistors R1 and R2
Since transistor Q1 continues to be ON until T ₂ , hold circuit 8 is kept in the HI state and relay K
1 will continue to be excited. That is, if the thermocouple 3 rises during this time _T2 , the input voltage at the non-inverting input terminal (+) of the hold circuit 8 becomes sufficiently high, so that the transistor Q1 turns on/off.
Regardless of whether it is OFF, the output of the hold circuit 8 remains HI and the transistor Q2 is turned ON, so that the relay K1 continues to be energized and the main valve 1 is kept open to perform normal combustion. On the contrary,
If the thermocouple 3 does not rise during this time T ₂ , that is, if a flame is not established, the charge in the capacitor C 2 ends and the transistor Q 1 turns OFF, at the same time the pseudo flame state is released and the hold circuit 8 The output will change to LO, and as a result, the contact K1-1 will be switched to close the main valve 1, and the DC power supply will be stopped, resulting in a safe stop. In other words, the present invention
Even if the user turns off the ignition switch, it will continue for a certain period of time T ₂
During this period, a pseudo-flame state is forcibly created, and if the thermocouple rises during this period, a normal combustion state is entered.

Here, a relay K is used to excite relay K1.
1. Transistor Q2, capacitor C3, resistor R
The circuit consisting of 8 and R9 has a fail-safe function. Although this relay drive circuit is a conventional technology, its failsafe property will be briefly explained here. That is, when transistor Q2 has a short failure, relay K1 will not be pulled in because the current is limited by resistor R9. Also, when transistor Q2 has an open failure, relay K1
Since no current flows through , relay K1 is never energized. It is normal for relay K1 to be pulled in. ON/OFF of transistor Q2
It is only when operation discharges the charge stored in capacitor C3 through relay K1 and transistor Q2. Relay K1 once pulled in
The excited state is maintained even with the current limited by the resistor R9.

Next, the significance of the delay time _T1 created by the capacitor C1 will be explained. This delay time
_T1 is provided to ensure that the capacitor C3 is sufficiently charged when the ignition switch 5 is turned on. In other words, even if a pseudo flame state is created and transistor Q2 is turned on when capacitor C3 is not sufficiently charged, relay K
This is because sufficient current is not extracted to pull in 1. Therefore, if the voltage of the transformer is taken out directly from the power supply 4 regardless of contact K1-1 and always applied, the ignition switch 5
There may be a question as to whether the delay time _T1 is unnecessary since charging of the capacitor C3 will have been completed by the time the capacitor C3 is turned on. However, in this case, the delay time of the hold circuit 8
Transistor Q provided to produce T ₂
It is not possible to maintain fail-safe property against the failure of the first one. In other words, in such a configuration where DC voltage is always applied and capacitor C1 is not required,
When the transistor Q1 has a short failure, the hold circuit 8 is switched to HI and the relay K1 is energized regardless of the ignition switch 5, so the main valve 1 opens and an extremely serious danger occurs. On the other hand, according to the present invention shown in FIG. 1, in which DC power is applied only when the ignition switch 5 is pressed, when the transistor Q1 has a shot failure, the hold circuit 8 is immediately turned HI when the ignition switch 5 is pressed. , and attempts to turn on transistor Q2 and pull in relay K1, but since DC power is applied at the same time as the ignition switch, capacitor C3 is not charged, so relay K1 is not pulled in. This provides a fail-safe effect. It should be noted that when the transistor Q1 has an open failure, no pseudo flame can be created, so the hold circuit 8 will not go HI, and no problem will occur.

Furthermore, the present invention can maintain fail-safe properties even in the event of an open failure of the thermocouple 3. That is, when the thermocouple 3 has an open failure, the input voltage at the non-inverting input terminal (+) of the hold circuit 8 is applied to the resistor R7 when the ignition switch 5 is turned on.
Since the potential of the DC power supply is maintained at a high potential through
However, at this time as well, since the capacitor C3 is not charged, the relay K1 is not pulled in and is fail-safe.

[Effect of idea]

As mentioned above, the present invention eliminates the inconvenience caused by the poor response of the thermocouple used for flame detection in a semi-automatic combustion device by creating a pseudo flame state. Furthermore, all of these functions are fail-safe, making it suitable for gas combustion safety devices that require high safety.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram of a semi-automatic combustion safety device showing an embodiment of the present invention, and FIG. 2 is a time chart for explaining the operation of an embodiment of the present invention.
is the time chart at the time of no ignition, B is the time chart at the time of ignition, 3rd
The figure is a schematic configuration diagram showing a conventional semi-automatic gas combustion safety device related to a stove. 1... Main valve, 2... Igniter, 3... Thermocouple (flame detection means), 4... Power supply, 5...
Ignition switch, 8...Comparison and hold circuit (comparison and hold means), Q1...Transistor (switching means), C1...Capacitor (first delay means), C2...Capacitor (second delay means), K
1-1... Relay contact (switching means), R7...
resistance.

Claims (1)

[Scope of utility model registration request] A flame detection means opens the main valve by pressing the ignition switch and starts fuel supply, and at the same time operates the igniter to detect the flame caused by the established ignition, and inputs the detected value of the flame detection means to the non-inverting input terminal. a comparison hold means for inputting and comparing a predetermined reference value to an inverting input terminal; a switching means for changing the reference value to produce a pseudo flame state when energized;
A first delay means that delays and energizes the switching means by a predetermined time T ₁ when the ignition switch is turned on, and a second delay means that deenergizes the switching means by delaying a predetermined time T ₂ when the ignition switch is turned OFF. and a relay excitation holding means having a fail-safe function that keeps the relay energized by the output of the comparison hold means, and when the relay is energized and held, the main valve is opened regardless of the ignition switch and power is supplied to each of the above means. an interlocking switch that operates in conjunction with the ignition switch to supply power to drive the relay excitation holding means; and an interlocking switch that operates in conjunction with the ignition switch to supply power to drive the relay excitation holding means; a resistor interposed between the connection point between the non-inverting input terminal (+) of the comparison hold means and one end (+) of the flame detection means and the DC power line so that the flame detection means enters a pseudo flame state. Semi-automatic combustion safety device.