JPH0330775B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a combustion safety device for household gas appliances using dry batteries or the like as a power source.

[Conventional technology]

As a combustion safety device for household gas appliances, a solenoid valve is held open by the electromotive force of a thermocouple heated by the pilot burner flame, and when the pilot burner flame goes out, the solenoid valve is automatically closed to shut off the gas. Those designed to do this have been widely adopted. However, this method has the inconvenience of having to keep the solenoid valve in the open position until the electromotive force of the thermocouple is generated during ignition.

In order to improve these points, a combustion safety device for gas appliances that uses dry batteries as a power source has been proposed and put into practical use. In this type of combustion safety device, when the ignition switch is turned on to ignite the burner, AC power is applied to the flame rod for detecting the presence or absence of burner flame to detect the presence or absence of flame, and while the burner flame is present, the solenoid valve is closed. The solenoid valve is held in the open position, and when the burner flame disappears, the solenoid valve is automatically closed to cut off the gas supply.

[Problem to be solved by the invention]

In this way, conventional combustion safety devices powered by dry batteries require continuous AC power to be applied to the flame rod while the device is in use in order to detect the presence or absence of a burner flame. In combustion safety devices that use limited electric power as a power source, this electric power for flame detection has a large effect on the battery life.

For this reason, there is no problem with appliances that are only used for a relatively short time, such as a small instantaneous gas water heater, but it is necessary to keep the pilot burner lit for a long time, such as with a bathtub or a bathtub with a water heater. In the case of certain gas appliances, there is a problem in that the battery life is shortened, making them unsuitable for practical use. In order to improve these problems, it is possible to reduce the current consumption supplied to the frame rod.
If this is done, there is a problem in that flame detection sensitivity deteriorates.

The main purpose of the present invention is to provide a combustion safety device for gas appliances that can improve the problems of the prior art as described above, and can significantly extend the life of dry batteries without impairing flame detection sensitivity. It is something to do.

Another object of the present invention is to provide a gas appliance with a circuit failure diagnosis function so that when a flame detection circuit component fails, the solenoid valve can be automatically closed to cut off the gas supply. The aim is to provide a combustion safety device.

[Means to solve the problem]

In order to solve the above-mentioned problems, the present invention has the following features:
A first switching element that turns on when a flame is detected and turns off when no flame is detected is connected in series with the solenoid valve circuit and the multivibrator circuit,
Further, the operation time when the first switching element turns off is delayed, and the AC power applied to the flame detection flame rod is intermittent by the multivibrator oscillation circuit, so that the oscillation period of the multivibrator oscillation circuit is adjusted. is set within the above delay time.

Further, the present invention connects in series with the first switching element a second switching element that is turned on when no flame is detected and turned off when a flame is detected, and the first and second switching elements are turned off. Furthermore, the alternating current power applied to the flame detection flame rod is intermittent by a multivibrator oscillation circuit, and the oscillation period of the multivibrator oscillation circuit is controlled by the first and second switching. It is characterized by being set within the delay time of the element.

[Effect]

A first switching element that is turned on when a flame is detected and turned off when no flame is detected is connected in series with the solenoid valve circuit, and the operation time when the first switching element is turned off is delayed; Since the multivibrator oscillation cycle is set within the above delay time, the first switching element is kept on and the solenoid valve is energized even though the AC power applied to the flame detection flame rod is intermittent.
In addition, the life of the battery can be extended by intermittent alternating current power applied to the flame rod, and furthermore, when no flame is detected for longer than the delay time, the solenoid valve is automatically closed to cut off the gas supply.

Moreover, the present invention connects a second switching element in series with the first switching element, which turns on when no flame is detected, and turns off when flame is detected, and the first and second switching elements are connected to each other. Since the operation time when turning off is delayed and the oscillation period of the multivibrator oscillation circuit is within the delay time, the above effect is achieved and the first
Due to the reverse ON/OFF action of the second switching element, the solenoid valve can be automatically closed to cut off the gas supply even if the flame detection circuit parts fail in either the flame detection or non-flame detection state. can.

〔Example〕

FIG. 1 is a circuit diagram showing a basic embodiment of the present invention. In this figure, 1 is a dry battery, 2 is a switch, and 3 is a constant current circuit consisting of transistors Q ₁ and Q ₂ and resistors R ₁ and R ₂ , and as described later, multivibrator oscillation is performed via a diode D ₁ . It is connected to the circuit 4 and the solenoid valve circuit 9. 5 is a blocking oscillation circuit consisting of a capacitor C ₁ , a transistor Q ₃ , a resistor R ₃ , and an oscillation transformer T. The secondary side of the oscillation transformer T is connected to a frame rod 6, and the frame rod 6 is opposite to a pilot burner 7. It is arranged. 8 is a capacitor
A smoothing circuit consisting of C ₂ , C ₃ and resistors R ₄ and R ₅ , whose output is a field effect transistor (hereinafter referred to as FET).
Connected to gate G of _Q4 . The FETQ ₄ is
When there is no flame, it is in a conductive state and has no resistance.
It is configured such that the voltage drop across R ₆ does not charge the capacitor C ₅ through the diode D ₂ .
Furthermore, when a flame is formed in the burner 7, the alternating current applied between the flame rod 6 and the burner flows in the form of a superimposed direct current component due to the rectifying action of the flame, and this direct current component is passed through the smoothing circuit 8 to the FETQ. ₄ is detected, the gate potential of FETQ ₄ becomes lower than the source potential and FETQ ₄ is turned off, and capacitor C ₅ is charged through diode D ₂ , which turns on transistor Q ₉ and connects it in series with the circuit of solenoid valve 9. Transistor _Q8 , which is the first switching element inserted in It is structured as follows. Note that 10 is a constant current circuit of a solenoid valve circuit including transistors Q ₁₃ and Q ₁₄ and resistors R ₂₀ and R ₂₁ . The multivibrator circuit 4 is composed of transistors Q ₁₀ and Q ₁₁ , capacitors C ₆ and C ₇ , and resistors R ₁₆ to R ₁₉ , and turns on and off the transistors Q ₁₀ and Q ₁₁ alternately. When Q ₁₁ is off, transistor Q ₁₂ is turned on and the potential of transistor Q ₁ of constant current circuit 3 is lowered through diode D ₁ , thereby temporarily stopping the power supply to blocking oscillation circuit 5. do.

Since the combustion safety device of the present invention is constructed as described above, even if the application of AC power to the flame rod 6 is intermittent and the life of the dry cell battery 1 is extended by the interruption period, the solenoid valve will remain open as long as there is a flame. Can be held continuously.

That is, when the switch 2 is closed, power is supplied to the blocking oscillation circuit 5 through the constant current circuit 3, and the alternating current generated by the transistor _Q3 and the oscillation transistor T is applied between the flame rod 6 and the burner 7 as a power source for flame detection. be done. At this time, when there is no burner flame, FET Q ₄ is in a conductive state, and due to the voltage drop across resistor R ₆ , capacitor C ₅ cannot be charged through diode D ₂ , and transistor Q ₉ is turned off. Therefore, the transistor which is the first switching element
Since _Q8 is also turned off and power is not supplied to the circuit of the solenoid valve 9, the solenoid valve 9 cannot be held by suction. When a flame is formed in the burner section, the alternating current applied between the flame rod 6 and the burner 7 is superimposed with a direct current component due to the rectifying action of the flame, and this direct current component is passed through the smoothing circuit 8 to the FETQ _4. Detect with.

When a DC component is detected, FETQ ₄ turns off and
Capacitor C ₅ is charged through diode D ₂ ,
Transistor _Q9 is turned on, transistor _Q8 , which is the first switching element, is turned on, power is supplied to the solenoid valve circuit, and solenoid valve 9 is attracted and held. At the same time, power is also supplied to the multivibrator oscillation circuit 4, and transistors _Q10 and _Q11 begin to alternately turn on and off. At this time, when the transistor Q ₁₁ is turned off, the transistor Q ₁₂ is turned on, and the base potential of the transistor Q ₁ of the constant current circuit is lowered through the diode D ₁ connected to the collector of the transistor Q ₁₂ , so the transistor Q ₁ is turned off. transistor Q ₂
Since the blocking oscillation circuit 5 is also turned off, the power supply to the blocking oscillation circuit 5 is stopped. When the power supply to the blocking oscillation circuit 5 is stopped, the AC power applied between the flame rod 6 and the burner 7 disappears, and flame detection becomes impossible.
FETQ ₄ turns on and charging to capacitor C ₅ stops. However, transistor Q ₉ continues to be on due to the charge on capacitor C ₅ ,
Transistor _Q8 , which is the first switching element
is also turned on. If the oscillation period of the multivibrator oscillation circuit 4 is set so that the charge in the capacitor _C5 is discharged through the resistor _R15 and the transistor _Q11 of the multivibrator oscillation circuit 4 is turned on before the transistor _Q9 is turned off, When transistor Q ₁₁ is turned on, transistor Q ₁₂ is turned off, transistor Q ₁ is turned on again, constant current circuit 3 is activated, power is supplied to blocking oscillation circuit 5 again, flame detection is performed, and FET Q ₄ is turned off. As a result, capacitor _C5 is charged.

In the present invention, even if power is intermittently supplied to the blocking oscillator circuit 5 as described above, the electromagnetic valve 9 is attracted and held as long as there is a flame, and when the flame disappears, the charge on the capacitor _C5 is When discharged through _R15 , transistor _Q9 turns off, and the first switching element, transistor _Q8, also turns off, closing the solenoid valve.

In this way, in the present invention, even if the current is supplied intermittently to the blocking oscillation circuit 5 for flame detection to reduce the current supply to 1/2 to 1/3 of the conventional one, the result is exactly the same as in the conventional case. The safety device can be operated without any problem.

FIG. 2 shows another embodiment of the present invention, which has the same functions and effects as the one shown in FIG. 1, but also has a circuit failure diagnosis function.

That is, in this embodiment, in addition to the first embodiment, a transistor Q 6 which is a second switching element is connected in series with a transistor Q ₈ which is a first switching element, and the transistor Q ₆ is connected in series with a transistor Q ₈ which is a first switching element. , transistor Q ₅ which turns on when FETQ ₄ is on (flame not detected) and the transistor
When _Q5 is turned on, capacitor _C4 is charged and turned on. Transistor _Q7 turns on the transistor _Q8 , which is the first switching element, in the opposite direction.
Control off.

Now, when FETQ ₄ is on (flame not detected),
Transistor Q ₅ turns on, charging capacitor C ₄ , transistor Q ₇ turns on. transistor
When Q ₇ turns on, the second switching element, transistor Q ₆ , turns on, but since the capacitor C ₅ is not charged through the diode D ₂ , the transistor Q ₉ remains off, and therefore the first
The switching element, transistor _Q8 , also remains off, and no power is supplied to the solenoid valve circuit.
Gas is shut off.

Next, when a flame is formed in burner 7,
FET _{Q 4} is in the off state (flame detection), charging capacitor C ₅ through diode D ₂ , turning on transistor Q ₉ and thus turning on the first switching element, transistor Q ₈ . FETQ ₄
detects flame and turns off, transistor _Q5 turns off and charging to capacitor _C4 stops.
However, the transistor _Q7 remains on due to the charge stored in the capacitor _C4 , and therefore the transistor _Q6 , which is the first switching element, also remains on, thereby supplying power to the solenoid valve circuit. The solenoid valve 9 is attracted and held.

On the other hand, when transistors Q ₆ and Q ₈ are turned on, power is supplied to the multivibrator circuit 4 and transistors Q ₁₀ and Q ₁₁ begin to turn on and off alternately, and when transistor Q ₁₁ is turned off, the state shown in FIG. In the same way as in the example, the AC power to flame rod 6 is stopped and FETQ ₄ is turned on (flame not detected).
do. When FETQ ₄ is turned on, capacitor C ₅ is no longer charged, but transistors Q ₉ and Q ₈ continue to be on due to the charge stored in capacitor C ₅ . In addition, in this case, the capacitor
Similar to the first embodiment, the oscillation cycle of the multivibrator oscillation circuit is set so that transistor Q ₁₁ of the multivibrator oscillation circuit is turned on before C ₅ is discharged and transistor Q ₉ is turned off. .

Then, the time constants of the capacitor _C5 and the resistors _R12 and _R15 are set so that the time that the transistor _Q9 is turned on without detecting a flame is within a range that does not pose any danger in use. In addition, the operation delay time of transistor Q ₇ is set to the sum of the charging time of capacitor C ₄ and the time until FETQ ₄ detects a flame and operates, + α, and the multivibrator oscillation circuit 4 oscillates. Set the cycle within this time.

In this way, if the first and second switching elements are turned on and off in opposite directions, a failure will occur in the flame detection circuit and, for example, FETQ ₄ will be in the flame detection state (even though there is no flame in the burner section). off), transistor _Q5 turns off and the capacitor
Charging to C ₄ is stopped, the electric charge of capacitor C ₄ is discharged through resistor R ₉ , transistor Q ₇ is turned off, and therefore the second switching element, transistor Q ₆ , is turned off and the solenoid valve circuit is turned off. Cut off.

Conversely, if a fault occurs that causes FETQ ₄ to remain in the on state (flame non-detection state), capacitor _C5 will not be charged, and the charge stored in capacitor _C5 will be transferred to resistors _R12 and R. ₁₅ and turns off the transistor _Q9 , thus turning off the first switching element, the transistor _Q8 , and interrupting the solenoid valve circuit.

Thus, in either mode of failure, no power is supplied to the solenoid valve circuit.

〔Effect of the invention〕

As described above, the present invention provides a combustion safety device powered by a battery that utilizes flame rectification, in which the life of the battery is extended by intermittent alternating current power applied to the flame rod for flame detection. Despite this, it can detect the presence or absence of flame with good sensitivity,
When the flame disappears, the solenoid valve can be automatically closed to cut off the gas supply.

Further, according to the present invention, circuit failure monitoring is also performed at the same time, and if a flame detection circuit component fails, the solenoid valve can be automatically closed to cut off the gas supply.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing a basic embodiment of the combustion safety device of the present invention, and FIG. 2 is a circuit diagram showing another embodiment. 1... Dry battery, 2... Switch, 3... Constant current circuit, 4... Multivibrator oscillation circuit, 5...
...Blocking oscillation circuit, 6...Frame rod, 7...Burner, 8...Smoothing circuit, 9...Solenoid valve, 10...Constant current circuit.

Claims (1)

[Claims] 1. In a combustion safety device powered by a battery that utilizes flame rectification, a first switching element that turns on when a flame is detected and turns off when no flame is detected is connected to a solenoid valve circuit and a multivibrator. The multivibrator oscillation circuit is connected in series with the oscillation circuit, and has a delay in operating time when the first switching element turns off, and furthermore, the AC power applied to the flame detection flame rod is intermittent by the multivibrator oscillation circuit. The oscillation period of the multivibrator oscillation circuit is set within the above delay time, so that the presence or absence of a flame can be continuously detected even though the AC power applied to the flame rod is intermittent when detecting a flame. A combustion safety device featuring: 2. In a combustion safety device powered by a battery that utilizes flame rectification, there is a first switching element that turns on when a flame is detected and turns off when no flame is detected, and a first switching element that turns on when no flame is detected and detects a flame. and a second switching element that turns off when the first and second switching elements turn off, and these two switching elements are connected in series with a solenoid valve circuit and a multivibrator oscillation circuit, and A time delay is provided, and the AC power applied to the flame detection flame rod is intermittent by the multivibrator oscillation circuit, and the oscillation period of the multivibrator oscillation circuit is set to the delay time of the first and second switching elements. The solenoid valve circuit is maintained by alternately turning on and off the first and second switching elements while the flame rod for flame detection is in contact with the flame, and the flame rod for flame detection is in a state where no flame is detected. 1st
When the delay time of the switching element elapses, the solenoid valve circuit is shut off, and when the flame detection circuit components fail and flame detection cannot be performed intermittently, the first switching element or the second switching element is turned off. A combustion safety device characterized in that it is designed to interrupt a solenoid valve circuit.