JPH02290417A - Safety device for combustion device such as hot water heater - Google Patents

Abstract

PURPOSE:To prevent first and second thermocouples and a solenoid valve itself from needing to set a set position and a working voltage with high precision by a method wherein a title device comprises a control means to compare a detecting thermoelectromotive force difference with a set thermoelectromotive force difference to generate a control output and the fuel gas solenoid valve of a burner controlled by means of a control output. CONSTITUTION:When incomplete combustion occurs due to deficiency in oxygen, the flame temperature of a pilot flame 2 is reduced, and the thermoelectromotive force of a first thermocouple 3 is decreased. When the combustion exhaust gas passage of a heat exchanger 4 is choked and an exhaust state is worsened, the temperature of the lower part of the interior of an inner drum 5 is increased and the thermoelectromotive force of a second thermocouple 6 is increased. In both cases stated above, a difference between the thermoelectromotive force of the first thermocouple 3 and the thermoelectromotive force of the second thermocouple 6 is decreased. When the thermoelectromotive force difference, i.e. a detecting thermoelectromotive force difference, is decreased to a value lower than a reference thermoelectromotive force difference preset by a set means 8, a control means 9 outputs a control output by means of which a fuel gas solenoid valve 10 is closed, and by closing the solenoid valve 10 in a way described above, the progress of an abnormal state can be reliably prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a safety device in combustion appliances such as water heaters.

(Prior Art) As a safety device for combustion appliances such as water heaters, there is one disclosed in Japanese Utility Model Publication No. 55-60051, for example, and as shown in Fig. 2, this device A second thermocouple f is connected in series with a pyloft safety circuit consisting of a first thermocouple C corresponding to the pilot flame b and an excitation coil e of the fuel gas solenoid valve d so as to reverse the direction of the thermoelectromotive force. This second thermocouple f is installed to correspond to the temperature of the lower part of the inner shell h of the heat exchanger g.

In such a configuration, when incomplete combustion occurs due to oxygen deficiency,
Due to the decrease in thermoelectromotive force of the first thermocouple C corresponding to the pilot flame b, the fuel gas solenoid valve d is closed, and the heat exchanger g
If the combustion exhaust gas passage is clogged and the exhaust condition worsens, a second thermocouple
The fuel gas solenoid valve d is closed due to the increase in thermoelectromotive force.

(Problem to be solved by the invention) The type of fuel gas used by the combustion appliance (for example, LPG, 1
3A and 6B), the length of the pilot flame b differs, so if the first thermocouple C is installed at the same position with respect to the pilot flame b, the thermoelectromotive force generated will vary depending on the gas type. . For example, if it is installed at the maximum flame temperature position for 6B gas, which has a short flame, it will be at the inner flame position for LPG, which has a long flame, so that the thermoelectromotive force will decrease. For this reason, the first thermocouple C must be installed at a different position depending on the type of gas, making design and adjustment complicated. Furthermore, in the conventional safety device, it is necessary to install the first and second thermocouples c and f and to set the operating thermoelectromotive force that closes the gas solenoid valve d with high precision.

The present invention aims to solve this problem.

(Means for Solving the Problems) The safety device of the present invention will be explained with reference to the illustrated embodiment. In order to solve the above-mentioned problems, the present invention provides a safety device corresponding to the pilot flame 2 of the burner 1 of the combustion appliance. a first thermocouple 3;
The difference between the thermoelectromotive force of the second thermocouple 6 corresponding to the inner lower part of the inner shell 5 of the heat exchanger 4 and the thermoelectromotive force of the first thermocouple 3 is means 7 for detecting, means 8 for setting a reference thermoelectromotive force difference, control means 9 for generating a control output by comparing the detected thermoelectromotive force difference and the set thermoelectromotive force difference, and controlled by the control output. Fuel gas solenoid valve 1 of the burner 1
0.

In such a configuration, the reference thermoelectromotive force difference setting means 8 includes:
For example, the reference thermoelectromotive force difference may be set by a changeover switch l2 having a display 11 corresponding to the type of fuel gas.

(Function) When incomplete combustion occurs due to oxygen deficiency, the flame temperature of the pilot flame 2 decreases, and the thermoelectromotive force of the tenth thermocouple 3 decreases. Further, when the combustion exhaust gas passage of the heat exchanger 4 is clogged and the exhaust condition worsens, the temperature in the lower part of the inner shell 5 rises, and the thermoelectromotive force of the second thermocouple 6 rises.

In any of the above cases, the difference between the thermoelectromotive force of the second thermocouple 6 and the thermoelectromotive force of the first thermocouple 3 becomes small. Therefore, when the thermoelectromotive force difference, that is, the detected thermoelectromotive force difference becomes smaller than the reference thermoelectromotive force difference preset in the setting means 8, the control means 9 controls the fuel gas solenoid valve 10. A control output is issued to close the solenoid valve 1.
By closing 0, it is possible to reliably prevent the abnormal state described above from progressing. In this way, the detected thermoelectromotive force difference that causes the solenoid valve lO to close can be appropriately set by the setting means 8, so that the first and second thermocouples 3.6 and the solenoid valve 10 itself can be adjusted at their installation positions. There is no need for highly accurate settings such as temperature and operating voltage, and even when the pilot flame 2 changes depending on the type of fuel gas, the setting means 8 can be adjusted without changing the installation position of the first thermocouple 3. , can be easily handled by simply changing the setting values. In particular, such setting means 8
For example, if the setting is configured to be set by a changeover switch 12 having a display 11 corresponding to the type of fuel gas, the setting can be easily changed.

(Embodiment) In FIG. 1 showing an embodiment, reference numerals 13 and 14 indicate amplifiers for obtaining a predetermined detection output corresponding to the thermoelectromotive force of each thermocouple 3.6. The means 7 for detecting the difference in the thermoelectromotive force based on the signals from these amplifiers 13 and 14 can be constituted by, for example, a differential amplifier. Further, the control means 9 can be easily constituted by a comparator, and the setting means 8 can be easily constituted by a variable resistor, a switching type variable resistor, or the like.

(Effects of the Invention) As described above, the present invention includes a first thermocouple corresponding to the pilot flame of a burner of a combustion appliance, a second thermocouple corresponding to the lower part of the inner shell of a heat exchanger, and a thermocouple connected to these thermocouples. In the safety device comprising a fuel gas solenoid valve controlled by a pair of fuel gas solenoid valves, the first
The difference between the thermoelectromotive force of the second thermocouple and the thermoelectromotive force of the second thermocouple is compared with a preset reference thermoelectromotive force difference to obtain a predetermined control output. The first and second thermocouples and the solenoid valves themselves do not require highly accurate settings such as their installation positions and operating voltages, and the first and second thermocouples do not require highly accurate settings such as their installation positions and operating voltages. This has the advantage that it can be easily handled by simply changing the setting value of the setting means without changing the installation position of the thermocouple 3. If the setting means is configured to be set by a changeover switch having a display corresponding to the type of fuel gas, for example, the setting can be easily changed.

[Brief explanation of drawings]

FIG. 1 is a system explanatory diagram of the present invention, and FIG. 2 is a system explanatory diagram of a conventional example. Symbol: Burner, 2: Pilot flame, 3: First thermocouple, 4: Heat exchanger, 5: Inner shell, 6...
・Second thermocouple, 7... thermoelectromotive force difference detection means, 8...
・Reference thermoelectromotive force difference setting means, 9...control means, 10.
... Fuel gas solenoid valve, 11... Display, 12... Changeover switch, 13, l4... Amplifier.

Claims (2)

[Claims] (1) The first flame corresponding to the pilot flame of the burner of the combustion appliance.
and a second thermocouple corresponding to the lower part of the inner shell of the heat exchanger, and detecting the difference in the thermoelectromotive force of the second thermocouple with respect to the thermoelectromotive force of the first thermocouple. means for setting a reference thermoelectromotive force difference; control means for generating a control output by comparing the detected thermoelectromotive force difference and the set thermoelectromotive force difference; and a fuel for the burner controlled by the control output. Safety device in combustion appliances such as water heaters consisting of a gas solenoid valve (2) The reference thermoelectromotive force difference setting means described in paragraph 1 is configured by a changeover switch having a display corresponding to the type of fuel gas.
A safety device for a combustion appliance such as a water heater, characterized in that it is configured to set the reference thermoelectromotive force difference.