JPH062845A - Safety device for burner - Google Patents

Abstract

PURPOSE:To improve the safe property of a safety device for a burner by a method wherein the safety device for burner, unable to be operated when a circuit is short-circuited by a wire instead of a temperature fuse upon the cutting of the temperature fuse, is provided. CONSTITUTION:A safety device 1 is constituted of a fusing member 2, cut by fusion by a temperature, and a fixed resistor 3, integrated with the fusing member 2, and when a power supply is thrown, the resistance of the safety device 1 is measured immediately. When the resistance of the safety device 1 is different from a given value, it is decided that the safety device 1 is short-circuited by a wire and the igniting operation of a gas burner is stopped.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a safety device for a combustor used in a combustor such as a water heater, a water heater or a steam boiler.

[0002]

2. Description of the Related Art A combustor is arranged below a heat exchanger such as a water heater to heat water flowing through the heat exchanger to produce hot water or steam. However, if some kind of failure occurs and the water in the heat exchanger is exhausted, the heat exchanger will be heated, and the heat exchanger will be damaged or a fire will occur.

Therefore, modern combustion devices are often equipped with a safety device for sensing the empty heating of the heat exchanger.

FIG. 3 is a front view of a combustor provided with a prior art combustor safety device. FIG. 4 is a block diagram of a conventional combustor safety device. First, the structure of the combustor will be described.
1 is inserted, and the heat exchanger 35 is arranged above the gas burner 31. An electromagnetic valve 33 is connected to the gas supply pipe 32 of the gas burner 31.

Prior art combustor safety devices include a combustion chamber 3
A safety device 34 such as a temperature fuse or a high limit temperature switch is provided near the heat exchanger 35 outside the zero temperature range.
The safety device 34 is wired in series with a circuit for operating the load 4 such as the solenoid of the solenoid valve 33 as shown in FIG.

In the conventional safety device for a combustor, when the combustor is heated to the air and the temperature of the heat exchanger rises abnormally, the heat causes the fuse of the safety device 34 to melt and the circuit of the load 4 to be cut off. . Then, the solenoid valve 33 is closed, the supply of gas to the gas burner 31 is stopped, and the combustion of the gas burner 31 is stopped.

[0007]

The prior art combustor safety device is extremely simple in construction, has few failures, and is highly reliable when used normally.

However, the safety device for a combustor according to the prior art can be modified so that the safety device does not function easily because the safety device is simply wired in the electric circuit of the load. That is, once the boiler fires, the safety device 3
When the thermal fuse of No. 4 is blown, the user or the like may intentionally short-circuit the safety device with an electric wire or wire close to him.

In the conventional safety device for a combustor, if the safety device is short-circuited with a wire, the gas burner 31 can be burned again, but of course, the original failure of the combustor is not repaired. Therefore, there is a high possibility that reheating will occur again, but the safety device does not operate at this time. Therefore, there is a risk that the heat exchanger will eventually have holes or a fire.

The present invention pays attention to the above-mentioned drawbacks of the conventional safety device for a combustor, detects a dangerous modification of the safety device, and enables some countermeasures, which makes it difficult to modify the safety device. By doing so, it is possible to prevent the safety device from being intentionally released, and to provide a safer safety device for the combustor.

[0011]

A feature of the present invention for achieving the above object is to provide a safety device for a combustor in which a safety device for interrupting a circuit due to temperature rise is arranged around a heat exchanger, The safety device has a certain resistance value,
A safety device for a combustor having resistance detection means for detecting the actual resistance of the safety device and safety control means for activating the safety function when the constant resistance value and the actual resistance of the safety device are different.

[0012]

In the safety device for a combustor according to the present invention, as in the prior art, a safety device for interrupting the circuit due to temperature rise is arranged around the heat exchanger. Therefore, in the unlikely event that the heat exchanger is boiled, the temperature of the heat exchanger body or the ambient atmosphere temperature rises, and the heat cuts the safety device and stops combustion.

In addition to this, the safety device used in the safety device for a combustor according to the present invention has a constant resistance value, and the resistance value of the safety device actually used is measured by the resistance detecting means. . Then, the security control means compares the constant resistance value which the safety device should have with the resistance value of the safety device which is currently used and detected by the detection means. Originally, if the cutout had not been modified, the resistance values should match. If the two are different, it is considered that the safety device has been modified by short-circuiting with a wire. Therefore, if they are different, the safety function is activated.

[0014]

EXAMPLES Specific examples of the present invention will be described below.

FIG. 1 is a block diagram of a safety device for a combustor according to a specific embodiment of the present invention. FIG. 2 is a flowchart of a combustor safety device according to a specific embodiment of the present invention.

In the present embodiment, the combustor itself is exactly the same as the conventional one, so the description of the combustor will be omitted by using the same numbers as those in FIG.

In FIG. 1, reference numeral 1 is a safety device. The disposition position of the safety device 1 is the same as that described with reference to FIG. 3 showing the description of the prior art, and it is easy to detect empty heating around the heat exchanger such as the surface, the upper part or the side part of the heat exchanger. Placed in position. The safety device 1 used in the present embodiment is one in which a fusing member 2 and a fixed resistor 3 that are fused at a constant temperature are connected in series, and both are integrated. The fusing member 2 has the same function as the thermal fuse of the prior art, and blows at a constant temperature to cut off the circuit. The fusing member 2 is different from the conventional thermal fuse in that the conventional thermal fuse has a structure that can be easily replaced.
The fusing member 2 has a structure in which it is physically difficult to replace it alone or short-circuit that part. The temperature at which the fusing member 2 melts is selected according to the installation position of the safety device. The fixed resistance 3 is preferably higher than the resistance value of a wire (zinc plated iron wire) normally used for short circuit of a safety device, and has a resistance that does not significantly hinder the power supply to the load 4.

The load 4 is the gas burner 31 as in the prior art.
Is a solenoid of a solenoid valve 33 provided in a pipe for supplying gas to the.

The controller 5 has a built-in resistance value storage means 6, resistance detection means 7, and security control means 8 in addition to a temperature control function similar to that of a known one. Here, the resistance value storage means 6 is the original resistance value of the entire safety device 1, that is, the fusing member 2 in a state in which nothing has been modified.
The total resistance value of the fixed resistance 3 and the fixed resistance 3 is stored in some form. The simplest configuration of the resistance value storage means 6 is a configuration in which a fixed resistor having the same resistance value as the safety device 1 is built in.

The resistance detecting means 7 is an object for measuring the actual resistance value of the safety device 1 currently used. The security control means 8 compares the stored value of the resistance value storage means 6 with the detection value of the resistance detection means 7. Then, as a result of the comparison, if the two are different, an alarm signal is output.

The display device 10 is a red lamp for notifying an abnormality.

The wiring of the safety device for a combustor of this embodiment is composed of a main circuit 11 and a resistance value measuring circuit 12. The main circuit 11 is a circuit similar to the conventional technology, and is a circuit that connects the controller 5, the safety device 1 and the load 4 in series.

The resistance value measuring circuit 12 is a circuit for connecting both ends of the safety device 1 and the controller 5. The output of the controller 5 is input to the display device 10.

Next, the operation of the combustor safety device of this embodiment will be described. In the safety device for a combustor of the present embodiment, in a normal state, that is, when not in an empty state, power is supplied from the controller 5 via the safety device 1 to operate a load.
When there is an abnormality, that is, when the heat exchanger is not heated, the fusing member 2 is blown and the operation of the load is stopped.

When the user turns off the power, replaces the safety device, and turns on the power again, first, the process proceeds to step 1 in FIG. 2 to check the resistance value of the safety device 2. Specifically, a current is passed from the controller 5 only to the resistance value measuring circuit 12, and the total resistance of the safety device 1 is measured by the resistance detecting means 7. Then, this measured value is compared with the resistance value previously stored in the resistance value storage means 6. If both are the same, the process proceeds to step 2 and subsequent steps, the main circuit 11 is energized, and the normal combustion control program is executed.

On the other hand, if the two resistance values are different, the process proceeds to step 3 and the controller 5 causes the display device 10 to change.
An alarm signal is output to and the alarm lamp blinks. In this case, the state where the main circuit 11 is not energized is maintained.
Therefore, the gas burner 31 does not ignite.

Here, the same range of the resistance value originally stored in the safety device 1 stored in the resistance value storage unit 6 and the actual resistance value of the safety device detected by the resistance detection unit 7 is the same as the error of the resistance value. Of course, it is necessary to consider the measurement error,
The temperature characteristics of the fixed resistance of the safety device should also be taken into consideration. In other words, in the present invention, it is not necessary that the resistance value that the safety device 1 originally has and the actual resistance value of the safety device be the same, and a considerable range is allowed.

For example, when the fixed resistance 3 of the safety device 1 is large to some extent, it is only confirmed whether or not the safety device has a resistance, in other words, the resistance of the safety device is 0 ohm, and if the resistance is 0 ohm. If so, the constant resistance value of the safety device and the actual resistance of the safety device are different, so that a configuration in which the process proceeds to step 3 is also possible. That is, the security control means of the present invention can be provided with means for checking whether or not the resistance of the safety device is 0 ohm and outputting an alarm signal.

In the present embodiment, the safety device 1 discloses the one in which the fusing member 2 and the fixed resistor 3 are connected in series. However, in addition to such a constitution, the material of the fusing member 2 is, for example, a conductive resin. It is also possible to select a material having a relatively high resistance value such as, and to provide the fusing member 2 itself with an electric resistance and omit the fixed resistance.

Further, in this embodiment, a resistance value measuring circuit 12 is provided separately from the main circuit 11 in order to measure the resistance value of the safety device 1. Although this configuration is a configuration that is sure to operate and is recommended, a configuration in which the resistance of the cutout is measured by using the main circuit is also possible in a simpler manner. That is, the sum of the resistance value of the load 4 and the resistance value of the safety device 1 is stored in advance in the resistance value storage means 6 in the controller 5. And the main circuit 11
The resistance value of the entire main circuit 11 is measured from the current flowing through the circuit and compared with the previously stored resistance value of the entire main circuit 11.
However, it should be noted that this configuration has a high overall resistance value when the impedance of the load is large.

It is sufficient to measure the resistance of the safety device 1 only once after the power is turned on as in the present embodiment, but of course the present invention does not deny the configuration of periodical measurement. Further, current is simultaneously applied to the main circuit 11 that operates the load 4 after the power is turned on and the resistance value measurement circuit 12 that measures the resistance value,
Immediately ignite the gas burner 31, measure the resistance of the safety device 1 in parallel with it, and if the constant resistance value of the safety device and the actual resistance of the safety device are different, the main circuit 11 is restarted.
It is also possible to adopt a configuration in which the current of 1 is cut off.

[0032]

According to the combustor safety device of the present invention, the safety device is provided with a constant resistance value, the actual resistance of the safety device is detected by the resistance detecting means, and the safety control means determines the constant value originally possessed by the safety device. Compare the resistance value with the actual resistance. Therefore, in the unlikely event of a modification such as a short circuit of the safety device, the actual resistance value will be different from the initial constant resistance value, and this can be used to detect a dangerous modification. When the modification of the safety device is detected, the safety function is activated and some countermeasure can be taken. Therefore, the safety device for a combustor of the present invention does not merely ensure the safety in the normal use state, but also can detect this modification if the user intentionally makes a dangerous modification, and the safety can be detected. Very effective.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a combustor safety device according to a specific embodiment of the present invention.

FIG. 2 is a flowchart of a combustor safety device according to a specific embodiment of the present invention.

FIG. 3 is a front view of a combustor provided with a prior art combustor safety device.

FIG. 4 is a block diagram of a conventional combustor safety device.

[Explanation of symbols]

 1 Safety device 2 Fusing member 3 Fixed resistance 4 Load 5 Controller 6 Resistance value storage means 7 Resistance detection means 8 Safety control means 35 Heat exchanger

Claims (1)

[Claims] 1. In a safety device for a combustor in which a safety device for interrupting a circuit due to a temperature rise is arranged around a heat exchanger, the safety device has a constant resistance value, and the actual resistance of the safety device is detected. A safety device for a combustor, comprising: resistance detecting means for performing a safety function; and safety control means for activating a safety function when the constant resistance value and the actual resistance of the safety device are different from each other.