JPH0238858B2 - NENSHOANZENSOCHI - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a combustion safety device using a CO sensor or other incomplete combustion detection element and a latching relay.

(Prior Art) The applicant of the present application has previously proposed an electromagnetic safety valve as a device of this type, which is interposed in a fuel supply path to a burner, and a drive circuit for the electromagnetic safety valve that connects an operating solenoid of the electromagnetic safety valve to a thermoelectric element. A control that opens when a gas concentration higher than a set value is detected by a latching relay connected to the power supply via a main switch that opens and closes in conjunction with turning on and extinguishing the burner, and a CO sensor or other incomplete detection element. an incomplete combustion detection circuit having a switch, the contacts of the latching relay are interveningly connected to the drive circuit so that when the burner ignition operation closes the main switch and the control switch is closed; The latching relay is set and the contacts are closed, and when the control switch is opened, the latching relay is reset and the contacts are opened, the electromagnetic safety valve is closed, and combustion of the burner is stopped. (Japanese Unexamined Patent Publication No. 1983-728).

(Problem to be Solved by the Invention) However, according to the above, in a normal state where the gas concentration is less than the set value, the control switch is closed, the latching relay is set, and its contacts are closed, the burner When you open the main switch to extinguish the fire, the latching relay remains in the set state. Even if the main switch is closed by the ignition operation, the electromagnetic safety valve drive circuit is activated because the latching relay contacts remain mechanically closed by the permanent magnet, but the incomplete combustion detection circuit is activated. Since there is no supply of power from the power supply, there is a disadvantage that the device is in an inoperable state and incomplete combustion cannot be detected, and it is desired to eliminate this problem.

(Means for Solving the Problems) The present invention attempts to eliminate the above-mentioned disadvantages by always resetting the latching relay when the main switch is opened by extinguishing the burner under normal conditions. An electromagnetic safety valve installed in the fuel supply path to the burner, a drive circuit for the electromagnetic safety valve that connects the operating solenoid of the electromagnetic safety valve to the thermoelectric element, and a main that opens and closes in conjunction with the burner's turning on and extinguishing operations. A latching relay connected via a switch and an incomplete combustion detection circuit having a control switch that opens when a gas concentration higher than a set value is detected by a CO sensor or other incomplete combustion detection element, and the latching A contact of a relay is connected to the drive circuit so that when the burner ignition operation closes the main switch and the control switch is closed, the latching relay is set and the contact closes, and the control switch is closed. In a device in which the latching relay is reset and the contact opens when the switch is opened, an open/close switch that opens and closes in conjunction with the burner turning on and extinguishing operations is connected to the incomplete combustion detection circuit. , the opening/closing switch is opened first by the main switch in conjunction with the extinguishing operation of the burner.

(Example) Next, the present invention will be explained based on the illustrated example.

In the drawing, 1 indicates an electromagnetic safety valve interposed in a gas supply path 3 which is a fuel supply path to the burner 2, 4 indicates a thermocouple which is a thermoelectric element facing the burner 2, and an operating solenoid 1a of the safety valve 1. The thermocouple 4 was connected through a contact 5a of a latching relay 5 to form a drive circuit 6 for the safety valve 1, in other words, a safety circuit for the burner 2 in the event of a misfire.

The latching relay 5 includes a set relay 7, a reset relay 8, and a small capacitor 9. When the capacitor 9 is charged, the set relay 7 is energized by the charging current and the contact 5a is closed. Further, when the potential at a connection point C, which will be described later, falls to approximately zero potential, the reset relay 8 is energized and the contact 5a is opened.

The latching relay 5 and incomplete combustion detection circuit 1
0 was connected to a dry battery 12 serving as a power source via a main switch 11 that opened and closed in conjunction with turning on and extinguishing the burner 2.

The incomplete combustion detection circuit 10 connects a voltage divider 15 consisting of a series connection circuit of a CO sensor 13 as an incomplete combustion detection element and a variable resistor 14 to a dry battery 12 via the main switch 11. 15 is connected to both bases of two series-connected PNP type transistors 17 and 18, which are control switches, through a diode 16, and the latch is connected to the connection point C between the collector of the transistor 18 and the resistor 19. Connect capacitor 9 of switching relay 5,
The emitter of the transistor 17 is connected to the CO sensor 13.
configured by connecting to.

Here, the present invention further provides an intervening connection to the circuit connecting the CO sensor 13 and the latching relay 5 with an open/close switch 20 that opens and closes in conjunction with the turning on and extinguishing operations of the burner 2. The opening/closing switch 20 is opened before the main switch 11 in conjunction with the operation.

In the figure, 21, 22, 23, 24, 25 are resistors for current adjustment, 26 is a capacitor for preventing malfunction,
27 represents a PNP transistor, and 30 represents a diode.

(Function) Next, to explain its operation, when the burner 2 is ignited, the main switch 11 is closed, and the open/close switch 20 is closed, the CO sensor 13 is held at a high resistance value, and the partial pressure point of the voltage divider 15 is Since the potential of D is held at a relatively low _V1 , both transistors 17 and 18 are turned on, and the capacitor 9 of the latching relay 5 is charged by the dry battery 12, and the charging current flows for a short time. The middle set relay 7 is energized and its contacts 5a are closed.
A drive circuit 6 is formed. At this time, since the burner 2 is burning, the thermocouple 4 is heated by the burner 2 and generates a predetermined electromotive force, causing the activation solenoid 1a
A current sufficient to keep the electromagnetic safety valve 1 open can be passed through the burner 2, and combustion in the burner 2 can be continued.

When the burner 2 burns normally and the CO sensor concentration is at a normal value below the set value, if the main switch 11 is subsequently opened by extinguishing the burner 2, the on/off switch 20 must be opened first. The latching relay 5 remains in the set state, and if the dry battery 12 serving as the power source becomes unusable due to a long period of time before the next ignition operation, or if you forget to turn on the power, the main switch 11 will be turned off at the next ignition operation. Even when the electromagnetic safety valve 1 is closed, the drive circuit 6 of the electromagnetic safety valve 1 is activated because the contact 5a of the latching relay 5 remains mechanically closed by a permanent magnet.
Since there is no supply of power, it becomes inoperable and incomplete combustion cannot be detected.However, in the present invention, the incomplete combustion detection circuit 10 is configured to open and close in conjunction with the burner 2 turning on and extinguishing operations. Since the on-off switch 20 is interposed and connected to open before the main switch 11 in conjunction with the extinguishing operation of the burner 2, when the on-off switch 20 opens, the two transistor 1
7 and 18 are both turned off, the potential of the connection point C becomes approximately ground potential, the reset relay 8 of the latching relay 8 is energized by the voltage of the dry battery 12, its contact 5a opens, and the solenoid operated by the thermocouple 4 is activated. The power to 1a is immediately cut off, and the electromagnetic safety valve 1 is closed. Therefore, whenever combustion in the burner 2 is stopped, the latching relay 5 is reset, its contact 5a opens, and the drive circuit 6 of the electromagnetic safety valve 1 returns to its inoperative state. Therefore, when the main switch 11 is closed by the next ignition operation, if the dry battery 12 is normal, the latching relay 5 is set, and the incomplete combustion detection circuit 10 and the drive circuit 6 of the electromagnetic safety valve 1 are both in the operating state. If the dry battery 12 is abnormal, the latching relay 5 remains reset with its contacts open, and both the incomplete combustion detection circuit 10 and the drive circuit 6 of the electromagnetic safety valve 1 remain inactive. .

Additionally, when the CO concentration reaches an abnormal value higher than the set value during combustion in the burner 2, the thermocouple 4 is heated and generates a predetermined electromotive force, but the CO sensor 13 changes to a resistance value, and the voltage divider Since the potential at voltage dividing point D of transistor 15 changes to relatively high _V2 , both transistors 1
7 and 18 are both turned off, the reset relay 8 is energized, its contact 5a opens, and the thermocouple 4
energization to the operating solenoid 1a is cut off,
The electromagnetic safety valve 1 is opened, combustion of the burner 2 is stopped, and it is safe.

(Effects of the Invention) According to the present invention, an open/close switch that opens and closes in conjunction with the burner's turning on and extinguishing operations is connected to the incomplete combustion detection circuit, and the switch opens and closes in conjunction with the burner's extinguishing operation. Since the switch is opened by the main switch first, when extinguishing the burner, the latching relay must be reset and its contacts can be opened, and when the main switch is closed by the next ignition operation, the power will return to normal. In that case,
The latching relay is set, and both the incomplete combustion detection circuit and the electromagnetic safety valve drive circuit are activated, and if the power supply is abnormal, the latching relay remains reset with its contacts open, preventing incomplete combustion. Both the detection circuit and the drive circuit of the electromagnetic safety valve remain in an inoperative state, which eliminates the above-mentioned disadvantage and has the effect of ensuring fail-safety against incomplete combustion.

[Brief explanation of drawings]

The drawing is a circuit diagram showing an example of implementation of the device of the present invention. 1... Solenoid safety valve, 1a... Operating solenoid,
2... Burner, 3... Gas supply path (fuel supply path),
4...Thermocouple (thermoelectric element), 5...Latching relay, 5a... Contact, 6... Drive circuit, 10...
Incomplete combustion detection circuit, 11...main switch,
12... Dry battery (power supply), 13... CO sensor (incomplete combustion detection element), 17, 18... Transistor (control switch), 20... Open/close switch.

Claims (1)

[Claims] 1. An electromagnetic safety valve interposed in the fuel supply path to the burner, a drive circuit for the electromagnetic safety valve that connects the operating solenoid of the electromagnetic safety valve to the thermoelectric element, and a power supply that opens and closes in conjunction with the burner's turning on and extinguishing operations. Latching relay connected via main switch and
and an incomplete combustion detection circuit having a control switch that opens when a gas concentration higher than a set value is detected by a CO sensor or other incomplete combustion detection element,
A contact of the latching relay is connected to the drive circuit so that when the burner is ignited, the main switch is closed and the control switch is closed, the latching relay is set and the contact is closed. , in which the latching relay is reset and the contact is opened when the control switch is opened, and the incomplete combustion detection circuit is provided with an open/close switch that opens and closes in conjunction with the burner turning on and extinguishing operations. 1. A combustion safety device characterized in that the opening/closing switch is opened before the main switch in conjunction with the extinguishing operation of the burner.