JP4161105B2 - Judgment device for combustion stop factor of gas instantaneous water heater - Google Patents

Description

  The present invention relates to a combustion stop factor determination device that can identify the cause of combustion stop of a burner, particularly in a gas instantaneous water heater installed in a kitchen or the like.

  Conventionally, gas instantaneous water heaters have been provided with safety measures for monitoring the combustion state to avoid accidents. For example, in Patent Documents 1 to 3 below, the degree of decrease in combustion temperature is detected, and it is determined whether the cause is due to incomplete combustion due to lack of oxygen or due to closing of the gas main valve. I was trying to do it.

However, when the combustion temperature is sufficiently high and the combustion is stable, there is no problem with these determination methods. However, in the configurations disclosed in Patent Documents 1 to 3, combustion immediately after the burner ignition is performed. Even if the gas main plug is closed at an unstable time, it is determined that the combustion is incomplete.
JP 2002-71131 A JP 2000-18579 A JP 2000-185851 A

  In view of the above, an object of the present invention is to provide a determination device capable of distinguishing whether the cause of the drop in the combustion temperature of the burner is due to incomplete combustion or due to the closing of the gas main plug. It is said.

  In order to solve the above-mentioned problems, the present invention provides a gas instantaneous water heater provided with a detection means for detecting a combustion temperature of a burner, a storage means for storing a threshold value for a detection value detected by the detection means, and the storage means A comparison means for comparing the threshold value stored in the detection value with the detection value detected by the detection means, and when the detection value exceeds the threshold value as a result of comparison by the comparison means, detection per unit time When the amount of decrease in the value is larger than the predetermined value set in advance, it is determined that the gas main valve has been closed, and when the amount of decrease in the detected value per unit time is smaller than the predetermined value set in If the detected value decreases without exceeding the threshold value as a result of determining that the incomplete combustion is caused by the comparison, the determining means is provided for determining that the gas main plug is closed.

  In the present invention, since the threshold is set at the boundary between the time when the combustion is not stable immediately after the burner is ignited and the time when the combustion is stable, the combustion temperature is the time when the combustion is not stable immediately after the burner is ignited. If the gas temperature drops, it can be determined that the gas main valve has been closed. Even when the combustion temperature decreases when the combustion of the burner is stable, incomplete combustion due to lack of oxygen, It is possible to appropriately determine whether or not it is due to the closure of.

  When a thermocouple is employed as the burner combustion temperature detection means, the change in the combustion temperature can be detected particularly accurately.

Hereinafter, embodiments of the present invention will be described.
FIG. 1 is a system diagram of a gas instantaneous water heater 100 embodying the present invention. As shown in FIG. 1, the gas instantaneous water heater 100 includes a heat exchanger 1. The heat exchanger 1 can be heated by a burner 4 having a spark plug 2 and a thermocouple 3. A coiled pipe 13 is arranged around the heat exchanger 1.

  The burner 4 is ignited by the spark plug 2 and heats a heat medium (not shown) in the heat exchanger 1. The pipe 13 is connected to a water supply pipe 12 provided with a water valve 11 in the middle. Water is heated while turning around the heat exchanger 1 from the water supply pipe 12 through the water valve 11 through the pipe 13 and heated to become hot water.

  On the other hand, a gas supply pipe 10 for supplying fuel gas is connected to the burner 4. An electromagnetic valve 8 and a gas governor 7 for adjusting the amount of gas supplied to the burner 4 are provided between the gas supply pipe 10 and the burner 4. Further, as shown in FIG. 1, the electrical circuit board 6 controls the opening degree of the electromagnetic valve 8 and the ignition of the spark plug 2.

  Further, the thermocouple 3 is connected to the electrical board 6 by wiring 22, and the electrical board 6 and the CPU 15 (microcomputer) are further connected by wiring 23. The thermocouple 3 detects the combustion temperature of the burner 4. A combustion temperature signal detected by the thermocouple 3 is transmitted to the electrical board 6 via the wiring 22, and the electrical board 6 transmits an electromotive force value signal having a magnitude corresponding to the combustion temperature of the burner 4 to the CPU 15 (output). ) The higher the combustion temperature value detected by the thermocouple 3, the higher the electromotive force value is output to the CPU 15.

  The CPU 15 includes a memory 16 (storage means). The memory 16 stores a threshold value of the electromotive force value of the thermocouple 3. This threshold value is set in advance so as to correspond to the boundary between the temperature region where the combustion of the burner 4 is unstable and the temperature region where the combustion is stable.

  FIG. 2 is a graph showing how the value of the electromotive force (unit: mV) of the thermocouple 3 in FIG. 1 changes. For a while after ignition by the spark plug 2, the electromotive force value of the thermocouple 3 has increased (the graph has risen to the right), but the combustion of the burner 4 is unstable. When the electromotive force value exceeds the threshold value and the combustion of the burner 4 is stabilized, the combustion temperature becomes constant and the electromotive force value becomes constant (the graph becomes horizontal). The thermocouple 3, the electrical board 6, the CPU 15, and the memory 16 constitute a determination device 50.

  By the way, if the gas main plug (not shown) is closed before the electromotive force value exceeds the threshold value (that is, before the combustion of the burner 4 is stabilized), the amount of decrease in electromotive force per unit time is relatively small. The value of electromotive force becomes small. When the gas main plug is closed after the value of the electromotive force exceeds the threshold value (that is, after the combustion of the burner 4 is stabilized), the value of the electromotive force is reduced in a relatively large state. Get smaller. In FIG. 2, the case where the amount of decrease per unit time is small is expressed as “gradient”, and the case where the amount of decrease per unit time is large is expressed as “steep”.

On the other hand, when an incomplete combustion state due to lack of oxygen occurs, an incomplete combustion state occurs, and the electromotive force value of the thermocouple continues to increase for a while and then gradually decreases. Therefore, in the graph of FIG. 2, the amount of decrease in electromotive force per unit time is relatively small. Accordingly, the determination device 50 can identify whether the combustion of the burner 4 has been stopped by closing the gas main valve or incomplete combustion has occurred in an oxygen deficient state. In FIG. 2, the electromotive force value of the thermocouple reaches the threshold value at time t ₁ , and shows both the case where the gas main plug is closed and the case where incomplete combustion occurs at time t ₂ .

  The above procedure is organized as shown in FIG. FIG. 3 is a flowchart for carrying out the present invention. First, the detection means (thermocouple 3) detects a combustion abnormality of the heat exchanger 1. In the next step, the comparison means (CPU 15) compares the detected value detected by the thermocouple 3 with a preset threshold value. If the detected value exceeds the threshold value, the process proceeds to the next step. If the amount of decrease in the detected value is greater than a predetermined value (the amount of decrease in the electromotive force of the thermocouple 1 per unit time), the determining means (CPU 15) Then, it is determined that the gas main plug is in a closed state, and if the amount of decrease in the detected value is smaller than a predetermined value, it is determined that misfire has occurred due to incomplete combustion. If the detected value does not exceed the threshold value, it is determined that the gas main plug is closed.

  In the above-described example, the thermocouple 3 is used as the means for detecting the combustion temperature of the burner 4. However, in addition to the thermocouple 3, for example, a flame detector (optical flame) that detects the combustion flame of the burner 4. A detector, a flame insertion type flame detector) can be employed.

It is a systematic diagram of the gas instantaneous water heater which implemented this invention. It is a graph which shows a mode that the electromotive force of a thermocouple changes. It is a flowchart at the time of implementing this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Heat exchanger 2 Spark plug 3 Thermocouple 4 Burner 6 Electrical board 7 Gas governor 8 Solenoid valve 10 Gas supply pipe 11 Water valve 12 Water supply pipe 13 Pipe 15 CPU (comparison means, judgment means)
16 Memory 20-23 Wiring 50 Judgment device 100 Gas instantaneous water heater

Claims (1)

In the gas instantaneous water heater equipped with a detecting means for detecting the combustion temperature of the burner,
A storage unit that stores a threshold value for the detection value detected by the detection unit; and a comparison unit that compares the threshold value stored in the storage unit with the detection value detected by the detection unit;
If the detected value exceeds the threshold value as a result of comparison by the comparison means, and the amount of decrease in the detected value per unit time is greater than a predetermined value, it is determined that the gas main valve has been closed. When the amount of decrease in the detected value per unit time is smaller than a predetermined value set in advance, it is determined that the combustion is incomplete due to lack of oxygen, and the comparison means compares the detected value to exceed the threshold value. An apparatus for determining a combustion stop factor of an instantaneous gas water heater, characterized in that a determination means for determining that the gas main plug has been closed is provided when the gas main plug is closed.

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