JPH0451733B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a safety device for combustion devices such as gas water heaters and gas hot water heaters.

Conventional configurations and their problems In recent years, as combustion devices such as water heaters have become more widespread in homes, there has been a demand for safer and easier-to-use combustion devices.

Hereinafter, a conventional safety device for a combustion device will be explained with reference to the drawings. FIG. 1 is a block diagram of a safety device for a conventional combustion device. In the figure, a temperature fuse 1 and a high limit switch 2 are safety devices of a conventional combustion device. Therefore, if the thermistor 3 opens, the combustion signal circuit 4 inputs a fully open signal for the gas proportional valve 6 to the central processing unit (hereinafter referred to as CPU) 5, even though the high set temperature is not reached. In response, the gas proportional valve 6 opens fully and abnormal combustion occurs.

Also, during abnormal combustion such as dry firing, the temperature fuse 1 and high limit switch 2 stop combustion.
High limit switch 2 had to be converted and restored, making it inconvenient to use.

Also, in winter, if the temperature of tap water is close to 0°C, the water in the heat exchanger 8 will freeze if the water is not drained, and in the worst case, the water in the water outlet pipe 7 and the heat exchanger 8 will freeze. There is also a danger that the water outlet pipe 7 and heat exchanger 8 may be destroyed.

Furthermore, the main valve 9 is opened by the valve driving device 15, the ignition device 10 is operated, the pilot burner 11 is ignited, and the ignition detection circuit 12 detects the pilot burner 1.
In a series of ignition operations in which the flame of 1 is detected and the flame is transferred to the main burner 3, the nozzle 14 that supplies gas to the main burner 13 is damaged due to some cause (for example, an impurity compound mixed in the gas). If it is clogged, pilot burner 11
Even if the flame is detected and an attempt is made to transfer the flame to the main burner 13 via the gas proportional valve 6, the nozzle 14 is clogged, so the amount of gas is less than normal and the flame does not transfer, and the ignition is not detected. However, there was a problem in that raw gas leaked out even though it was in use, causing an accident. Note that 16 is a power source.

Purpose of the Invention In view of the above-mentioned drawbacks, the present invention is designed to stop combustion when the thermistor is abnormal or when there is abnormal combustion such as dry firing.
Further, the present invention provides a safety device for a combustion device that allows for easy return operation and stops the combustion device using a protective means in the event of freezing.

Structure of the Invention To achieve this object, a safety device for a combustion apparatus of the present invention includes: a main burner, a pilot burner for transferring fire to the main burner for combustion, and an ignition device for igniting the pilot burner. an ignition detection circuit for detecting ignition; a heat exchanger heated by the main burner; a water outlet pipe for discharging water heated by the heat exchanger; a thermistor provided in the water outlet pipe; An A/D converter converts the signal detected by the thermistor into a digital signal, and the signal from the A/D converter is processed, and the abnormal state of the thermistor is detected. Freezing prevention, heat exchanger overheating prevention, CPU that determines if there is a fire transfer failure to the main burner, a valve drive device that stops combustion of the main burner based on the output signal of the CPU, and freezing of the heat exchanger of the CPU, etc. and protective means activated by a precautionary signal.

With this configuration, in the event of an abnormality in the thermistor or abnormal combustion such as dry firing, sintering is stopped, and in the event of freezing, freezing is notified by means such as issuing an alarm to predict freezing. This prevents fire from spreading and detects the problem and stops the equipment, thereby preventing accidents.

DESCRIPTION OF EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 2 is a block diagram of a safety device for a combustion device in one embodiment of the present invention. The same numbers as in FIG. 1 indicate the same items.

In the figure, the signal from the thermistor 3 is converted into a digital signal by the A/D converter 18, and the signal is always sent to the CPU 5.
The CPU 5 makes a judgment and outputs based on the digital signal.

When thermistor 3 is open short, the resistance of thermistor 3 becomes ∞Ω・0Ω, and the A/D converted value becomes &H “O” or &H “FF” after A/D conversion, which can ^normally be obtained. will have no value,
An abnormality in the thermistor 3 can be identified.

During abnormal combustion such as dry firing, water outlet pipe 7, heat exchanger 8
temperature becomes a temperature that cannot normally be reached, and the resistance value of the water output thermistor 3 also takes a value close to that when the thermistor 3 is open, and abnormal combustion can be detected in the CPU 5, and the temperature fuse and high limit switch 2 are activated. Combustion can be stopped before operation. Therefore, it can be restored by power reset or other operations, making it more convenient to use.

If the temperature characteristics of the thermistor 3 are known, it is possible to recognize temperatures near 0° C., and freezing can be prevented by the protection means 17.

In addition, fire transfer abnormality can be detected by the thermistor 3 after ignition is detected.
It can be recognized by measuring the temperature gradient.

Note that FIG. 3 is a thermistor characteristic diagram of a combustion device in one embodiment of the present invention. In the same figure, if normal (A), the water temperature in the water outlet pipe 7 will rise even if the combustion is the minimum after ignition is detected, the temperature of the thermistor 3 will rise accordingly, and the CPU 5 will increase due to A/D conversion.
The digital signal input into the device also has an upward slope. In the case of defective flame transfer (B), since the main burner 13 is not lit after ignition is detected, heat is not exchanged and the temperature of the thermistor 3 does not rise, and defective flame transfer can be detected.

Effects of the Invention According to the safety device for a combustion device of the present invention, the following effects can be obtained.

(1) If the thermistor becomes abnormal, combustion will be automatically stopped to ensure safety.

(2) When freezing temperatures are reached, protective measures to prevent freezing can be activated, thereby preventing accidents due to freezing of heat exchangers or water pipes.

(3) Since failure of fire transfer can be detected, raw gas leakage and related accidents can be prevented.

[Brief explanation of the drawing]

FIG. 1 is a block wiring diagram of a conventional safety device for a combustion device, FIG. 2 is a block wiring diagram of a safety device for a combustion device according to an embodiment of the present invention, and FIG. 3 is a thermistor characteristic diagram of the same device. 3... Thermistor, 5... CPU, 8... Heat exchanger, 10... Ignition device, 11... Pilot burner, 12... Ignition detection circuit, 13... Main burner, 15... A/D converter , 16... protection measures.

Claims (1)

[Claims] 1 A main burner, a pilot burner for transferring flame to the main burner for combustion, an ignition device for igniting the pilot burner, an ignition detection circuit for detecting ignition, and a heat exchanger heated by the main burner. a water outlet pipe for discharging the water heated by the heat exchanger; a thermistor provided in the water outlet pipe; and an A/R for converting the signal detected by the thermistor into a digital signal.
The signals from the D converter and the A/D converter are processed, and the abnormal state of the thermistor is detected, and the signal from the thermistor is used to prevent freezing of the heat exchanger and water outlet pipes, prevent overheating of the heat exchanger, and send to the main burner. a CPU that determines whether there is a flame transfer failure in the burner; a valve drive device that stops combustion of the main burner based on an output signal from the CPU;
A safety device for combustion equipment equipped with a protection means activated by a signal to prevent freezing of CPU heat exchangers, etc.