JPH0223972Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a safety device for gas water heaters and other combustors that detects the generation of flammable gas and stops combustion of the burner.

(Prior Art) As a conventional device of this kind, an electromagnetic safety valve is interposed in the fuel supply path to the burner, and a first thermoelectric generating element that is heated by the burner and generates an electromotive force is used as the operating solenoid of the electromagnetic safety valve. A power supply consisting of a second thermoelectric generator separate from the first thermoelectric generator is connected to the operating solenoid via a CO sensor to configure a drive circuit for the electromagnetic safety valve, and the first thermoelectric generator is connected to the operating solenoid via a CO sensor. The electromagnetic safety valve is connected to the opposite polarity to form an abnormality detection circuit, and when the resistance of the CO sensor decreases when CO is generated, the power supply voltage with the opposite polarity to that of the first thermoelectric generator is applied to the operating solenoid, and the electromagnetic safety valve is activated. A device in which the valve is closed is known (see Utility Model Application Publication No. 112850/1983).

In this device, an electromotive force V _T of the thermoelectric generating element and a voltage V C corresponding to the resistance value of the CO sensor from the power source are applied to the operating solenoid, and if the CO concentration gradually increases, the voltage V _C from the power source is applied accordingly. As the voltage V _C increases, the relationship between the combined voltage (V _T −V _C ) of the thermoelectric generator and the power source applied to the operating solenoid and the CO concentration is as shown by the chain line in FIG. , as the CO concentration increases, the composite voltage (V _T −V _C ) decreases continuously, and when the CO concentration is at the permissible value P ₁ , the composite voltage applied to the actuating solenoid will cause the electromagnetic safety valve to disconnect. The voltage value _V1 is set to correspond to the current value. However, according to this, when the actual CO concentration is, for example, _P2 , which is slightly lower than the allowable value _P1 , the combined voltage (V _T −V _C ) is
V ₂ , and the electromagnetic safety valve is held in the open state, but the attraction force of the electromagnetic safety valve by the operating solenoid at this time is weak. When mechanical vibration is applied to the combustor, the adsorption of the electromagnetic safety valve may be released and the valve may close even though the CO concentration is below the allowable value _P1 , impairing the reliability of the safety device. There is an inconvenience.

(Problems to be Solved by the Present Invention) Therefore, in order to eliminate the above-mentioned inconvenience, the applicant of the present application first installed an electromagnetic safety valve in the fuel supply path b to the burner a, as shown in FIGS. 2 and 3. Interpose c.
A thermoelectric generating element d that is heated by the burner a and generates an electromotive force is connected to the operating solenoid c1 of the electromagnetic safety valve c to constitute a drive circuit e of the electromagnetic safety valve c, and also includes a CO sensor and other gas sensors f. and an abnormality detection circuit h that applies a voltage from a power source g connected with a polarity opposite to that of the thermoelectric generator d to the operating solenoid C1 in response to a change in the output of the gas sensor f when combustible gas is generated. The abnormality detection circuit h is constructed by intervening and connecting a switching element i that becomes conductive when the output of the gas sensor f reaches a predetermined value to a circuit that connects the power supply g to the actuation solenoid c1. Before the output of the gas sensor f during gas generation reaches a predetermined value, only the voltage from the thermoelectric generating element d is applied to the actuating solenoid c1, and when the output reaches the predetermined value, the switching element i is made conductive, and the actuating solenoid c1 is turned on. A method was proposed in which a voltage of opposite polarity to that of the thermoelectric generator d was applied to close the electromagnetic safety valve c, thereby stopping combustion in the burner a (Utility Application No. 59-66093).

An object of the present invention is to provide a combustor safety device that further improves the reliability of the abnormality detection circuit h.

(Means for Solving the Problems) In order to achieve the above object, the present invention provides an electromagnetic safety valve in the fuel supply path to the burner, and a thermoelectric generating element that is heated by the burner and generates an electromotive force. is connected to the operating solenoid of the electromagnetic safety valve to form a drive circuit for the electromagnetic safety valve, and also includes a CO sensor or other gas sensor, and the operating solenoid is activated to generate thermal power by changing the output of the gas sensor when flammable gas is generated. The device is equipped with an abnormality detection circuit that applies a voltage from a power source connected with a polarity opposite to that of the element, and the abnormality detection circuit applies a voltage to a circuit connecting the power source to the actuating solenoid when the output of the gas sensor reaches a predetermined value. In the gas sensor, a plurality of at least one of the gas sensor and the switching element are connected in parallel.

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

In FIG. 4, reference numeral 1 denotes an electromagnetic safety valve interposed in a fuel supply path 3 to a burner 2, and its operating solenoid 1a is connected to a thermocouple 4, which is a thermoelectric generating element that is heated by the burner 2 and generates an electromotive force. The drive circuit 5 of the electromagnetic safety valve 1 was constructed by connecting them.

The drive circuit 5 normally maintains the electromagnetic safety valve 1 open and closes it.

Furthermore, the abnormality detection circuit 6 was constructed by connecting the operating solenoid 1a to a power source via a switching element that becomes conductive when the output of the gas sensor reaches a predetermined value. In this case, the gas sensor was a CO sensor 7 for detecting the CO concentration in combustion exhaust, the switching element was a transistor 8, and the power source was a battery 9. The abnormality detection circuit 6 includes a CO sensor 7
The electromagnetic safety valve 1 is closed by applying a battery 9 voltage having a polarity opposite to the electromotive force of the thermocouple 4 to the operating solenoid 1a by the change in the output of the thermocouple. , first, second and third resistors 1
0, 11, 12 and the CO sensor 7, and the connection point A between the first resistor 10 and the second resistor 11 and the connection point B between the third resistor 1 and the CO sensor 7 are connected as follows. A circuit that connects to each input terminal C, D of the AND circuit 14 of the stage, connects the output terminal E of the AND circuit 14 to the base of the transistor 8, and connects the transistor 8, the battery 9, and the operating solenoid 1a. Intervening and connecting.

This abnormality detection circuit 6 sets the values of the first and second resistors 10 and 11 so that a voltage corresponding to a predetermined value of CO concentration, for example 300 PPM, is obtained at the connection point A. in the combustion exhaust of
When the CO concentration reaches a predetermined value, the resistance value of the CO sensor 7 decreases from the usual 10 to 100KΩ to about 500KΩ, and a voltage equivalent to that at connection point A is obtained at connection point B, and the AND circuit A high level output is obtained from 14, transistor 8 becomes conductive, and the thermocouple 1 is connected to the operating solenoid 1a of the electromagnetic safety valve 1.
A voltage of opposite polarity to the electromotive force No. 4 is applied.

Although the above configuration is not particularly different from the device previously proposed by the applicant, its operation will be explained as follows.

When the CO concentration in the exhaust gas is below a predetermined value _P1 , only the voltage V _T from the thermocouple 4 is applied to the operating solenoid 1a of the electromagnetic safety valve 1, as shown by the solid line in Figure 1, and the electromagnetic safety valve 1 is opened. burner 2, but the CO concentration increases and reaches the predetermined value.
When P exceeds ₁ , the resistance value of the CO sensor 7 decreases,
Transistor 8 conducts and the actuating solenoid 1a
A voltage V _C from the battery 9 is applied to. Since this voltage acts to cancel the voltage applied by the thermocouple 4, the terminal voltage of the actuating solenoid 1a is reduced, the electromagnetic safety valve 1 is closed, and combustion in the burner 2 is stopped.

The above configuration includes one CO sensor 7 as a gas sensor and one transistor 8 as a switching element, and if these fail for some reason, they will no longer function as a safety device.
In the present invention, a plurality of at least one of the gas sensor and the switching element are connected in parallel,
Even in the above case, it functions as a safety device.

To explain this specifically, in the one shown in FIG. 4, two transistors 8 are connected in parallel so that even if one transistor 81 fails, the abnormality detection circuit 6 is activated by the other transistor 82. did. In this case, one transistor 81
The transistor 82 is made of a transistor having better heat resistance than the other transistor 82, thereby further improving the reliability of the abnormality detection circuit 6.

In the above embodiment, the transistor 8 is used as the switching element, but a thyristor 15 can be used as shown in FIG. 5 to perform the same operation. In this one, the thyristor 1
5 and CO sensor 7 are connected in parallel,
One thyristor 151 or/and one CO
Even if the sensor 71 fails, the abnormality detection circuit 6 is made to work by the other thyristor 152 and the other CO sensor 72. In this case, one thyristor 151 is configured with one that has better heat resistance than the other thyristor 152, and one CO sensor 7
1 is made of a material having better heat resistance than the other CO sensor 72, so that the reliability of the abnormality detection circuit 6 is further improved.

(Effects of the present invention) As described above, the present invention is constructed by connecting in parallel a plurality of at least one of the gas sensor and the switching element of the abnormality detection circuit that closes the electromagnetic safety valve in the event of an abnormality due to the generation of flammable gas. This has the effect of improving the reliability of the safety device compared to a device that includes one gas sensor and one switching element.

[Brief explanation of the drawing]

Figure 1 is an explanatory diagram showing the relationship between the voltage applied to the operating solenoid of the electromagnetic safety valve and the CO concentration.
3 and 3 are explanatory diagrams of the first and second embodiments of the device previously proposed by the applicant, FIG. 4 is an explanatory diagram showing one example of implementation of the device of the present invention, and FIG. FIG. 7 is an explanatory diagram showing another embodiment of the device of the present invention. 1... Solenoid safety valve, 1a... Operating solenoid,
2... Burner, 3... Fuel supply path, 4... Thermocouple (thermal power generation element), 5... Drive circuit, 6... Abnormality detection circuit, 7, 71, 72... CO sensor (gas sensor), 8 , 81, 82...Transistor (switching element), 9...Battery (power supply), 15, 15
1,152...Thyristor (switching element).

Claims (1)

[Claims for Utility Model Registration] 1. An electromagnetic safety valve is interposed in the fuel supply path to the burner, and a thermoelectric generating element that is heated by the burner and generates an electromotive force is connected to the operating solenoid of the electromagnetic safety valve. In addition to configuring the drive circuit of the safety valve, it has a CO sensor or other gas sensor, and when combustible gas is generated, a voltage from a power source connected to the thermoelectric generator is connected to the operating solenoid in response to a change in the output of the gas sensor when flammable gas is generated. The abnormality detection circuit is configured by intervening and connecting a switching element that becomes conductive when the output of the gas sensor reaches a predetermined value to a circuit that connects the power source to the actuating solenoid. A safety device for a combustor, characterized in that a plurality of at least one of the gas sensor and the switching element are connected in parallel. 2. The safety device for a combustor according to claim 1, wherein a plurality of gas sensors are connected in parallel, and at least one of the gas sensors is made of a material having better heat resistance than the others. 3. A safety device for a combustor according to claim 1 of the utility model registration claim, characterized in that a plurality of switching elements are connected in parallel, and at least one of them is made of a material with better heat resistance than the others. .