JPS6247010Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a combustion safety device in which an electromagnetic safety valve that is inserted into a fuel passage of a combustion appliance and opens and closes the passage is held open by the output of a combustion detection element.

As shown in Fig. 1, a conventional device of this kind is
The output of the oscillation circuit b operated by the output of the combustion detection element a is applied to the switching element g connected in series with the excitation coil f of the electromagnetic safety valve e through the detection circuit c and the smoothing circuit d in order, and turns on the element g. A type is known in which the safety valve e is held open (Tokuko Showa).
(See Publication No. 55-1492).

However, this device uses a thyristor as the switching element g, and in the event of a short-circuit failure between the anode and cathode of the thyristor g, the sum of the resistances of the resistance h and the resistance of the exciting coil f will be the sum of the resistances of the smoothing capacitor i. If it is set to be higher than the impedance, the AC component passes through the capacitor i, so the current flowing to the excitation coil f becomes less than the holding current of the electromagnetic safety valve e, and the safety valve e is closed, but the thyristor g In the event of a short-circuit failure between the anode and the gate, the thyristor g will function as a diode, a half-wave current will flow to the cathode side, and the safety valve e will be held open as in normal operation, and the combustion appliance There was an inconvenience that fuel was continuously supplied to the

The purpose of the present invention is to provide a device that eliminates the above-mentioned disadvantages, and as shown in FIG. In a type in which the valve is held open by the output of the element 4, the detection element 4
, a switching element 6 that is turned on and off by the output of the oscillation circuit 5, and a first capacitor 7 that is charged when the switching element 6 is turned off and discharged when it is turned on. The present invention is characterized in that the excitation coil 3a of the safety valve 3 and the second capacitor 9 are connected in parallel to each other in the discharge circuit 8 of the first capacitor 7.

In the illustrated example, the combustion appliance 1 is composed of a burner, and the combustion detection element 4 is composed of a thermocouple.
Incidentally, as the combustion detection element 4, a conventionally known flame rod, semiconductor gas sensor, etc. may be used.

Further, the switching element 6 is constituted by an NPN type transistor, and the output of the oscillation circuit 5 is applied to the base 6b of the switching element 6, so that the switching element 6 is alternately turned ON and OFF.

In the figure, 10 is a charging circuit 11 for the first capacitor 7.
12 indicates a first diode inserted in the discharge circuit 8 of the first capacitor 7. In FIG.

In addition, 13 indicates a power source for this combustion device, and 1
4 and 15 indicate current limiting resistors.

Next, to explain its operation, when the burner 1 is extinguished, no output is obtained from the thermocouple 4, the transistor 6 is OFF, and therefore the power source 1
3-resistor 14-first capacitor 7-first diode 10-power supply 13 are connected in series in this order to constitute a charging circuit, and the first capacitor 7 is charged.
In this case, the second diode 12 is reverse biased and the excitation coil 3a of the electromagnetic safety valve 3 is not energized.

Thereafter, when the electromagnetic safety valve 3 is forcibly opened by manual operation and the burner 1 is ignited, a thermoelectromotive force is generated from the thermocouple 4, and an output as shown in FIG. 3 is obtained from the oscillation circuit 5, for example. When the level is high, the transistor 6 is turned on, and the parallel circuit of the first capacitor 7, the transistor 6, the excitation coil 3a of the electromagnetic safety valve 3, and the second capacitor 9, the second diode 12, and the first capacitor 7 are connected in series in this order. A discharge circuit 8 is configured to discharge the first capacitor 7. During this discharge, the exciting coil 3a
is energized, the electromagnetic safety valve 3 is held open,
Fuel is supplied to the burner 1, the burner 1 continues to ignite, and the second capacitor 9 is charged.

Next, when the output of the oscillation circuit 5 changes to LOW level, the transistor 6 is turned off, the discharge circuit 8 is disconnected, and the first capacitor 7 is de-energized to the excitation coil 3a. The second capacitor 9 charged by the discharge of 7 starts discharging, and the output of the oscillation circuit 5 becomes the next one.
The electromagnetic safety valve 3, which was previously held open by the first capacitor 7 by energizing the excitation coil 3a, is further held open until the level reaches the High level.

Thereafter, the above operation is repeated while an output is obtained from the thermocouple 4.

Next, the operation when each element fails in the safety device of the present invention will be explained.

When the transistor 6 fails If the transistor 6 has a short-circuit failure, the first capacitor 7 is not charged, and therefore the excitation coil 3 of the electromagnetic safety valve 3 due to the discharge of the first capacitor 7
A is not energized.

If the transistor 6 is disconnected, the discharge circuit 8 of the first capacitor 7 is not configured and the second capacitor 9 is not charged. 3a is not energized.

In both of the above cases, the electromagnetic safety valve 3 is closed and fuel is not supplied to the burner 1.

When the first capacitor 7 fails When the first capacitor 7 has a short-circuit failure or a disconnection failure, the first capacitor 7 is not charged and the excitation coil 3a is not energized.
The electromagnetic safety valve 3 is closed and fuel is not supplied to the burner 1.

When the second capacitor 9 malfunctions When the second capacitor 9 malfunctions due to a short circuit, the potential difference between both ends of the excitation coil 3a becomes extremely small.
The electromagnetic safety valve 3 cannot be opened by the excitation coil 3a.

If the second capacitor 9 has a disconnection failure, the excitation coil 3a is temporarily energized by the discharge of the first capacitor 7 when the transistor 6 is ON;
Since the second capacitor 9 is not charged, the second capacitor 9 is not discharged when the transistor 6 is OFF, the exciting coil 3a is not energized, and the electromagnetic safety valve 3 cannot be kept open.

As described above, according to the present invention, the switching element 6 is turned ON and OFF by the output of the oscillation circuit 5 operated by the output of the combustion detection element 4, and when the switching element 6 is OFF, the first capacitor 7 is charged, and the switching element 6 is turned OFF. When element 6 is ON, first capacitor 7
The electromagnetic safety valve 3 is held open by the discharge of the electromagnetic safety valve 3 and the second capacitor 9 is charged, and when the switching element 6 is next turned off, the electromagnetic safety valve 3 is held open and the first capacitor 7 Since the electromagnetic safety valve 3 is always closed even if each element constituting the device is short-circuited or disconnected, safety and reliability are further improved compared to conventional devices. It has the effect of

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram of a conventional device, FIG. 2 is a circuit diagram showing an example of the device of the present invention, and FIG. 3 is a waveform diagram showing an example of an output waveform of an oscillation circuit. DESCRIPTION OF SYMBOLS 1... Combustion appliance, 2... Fuel passage, 3... Electromagnetic safety valve, 3a... Excitation coil, 4... Combustion detection element, 5... Oscillation circuit, 6... Switching element,
7...First capacitor, 8...Discharge circuit, 9...
Second capacitor.

Claims (1)

[Scope of utility model registration request] In a type in which an electromagnetic safety valve 3 that intervenes in a fuel passage 2 of a combustion appliance 1 and opens and closes the passage 2 is held open by the output of a combustion detection element 4, an oscillation circuit 5 operated by the output of the detection element 4 is used. , a switching element 6 that is turned ON and OFF by the output of the oscillation circuit 5, and a first capacitor 7 that is charged when the switching element 6 is OFF and discharged when the switching element 6 is ON. A combustion safety device characterized in that an excitation coil 3a of a safety valve 3 and a second capacitor 9 are connected in parallel with each other.