JPH04295511A - Device to prevent incomplete combustion - Google Patents

Abstract

PURPOSE:To detect and prevent surely the incomplete combustion even when the gas volume is changed in the middle of combustion. CONSTITUTION:It is judged as incomplete combustion when the temperature in the combustion chamber 3 in the state of steady combustion falls from a reference temperature TS by a specified temperature range T, and a gas shut-out value 13 is thereby operated to stop the gas supply and, at the same time, if the supply volume of the gas is different from a reference volume, the temperature of the combustion chamber 3 is converted and corrected to the temperature in the state of steaby combustion according to the gas supply volume. It is judged to be incomplete combustion when the corrected temperature TA falls from a reference temperature TS by a specified temperature range T, and the gas shut-out valve 13 is operated to stop the gas supply.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an incomplete combustion prevention device for gas combustion devices such as fan heaters and gas water heaters.

0002

[Prior Art] Conventional incomplete combustion prevention devices for gas combustion devices such as fan heaters, for example, place a thermocouple in the combustion chamber, and the temperature of the combustion chamber in the initial combustion state (reference temperature) When the electromotive force of the thermocouple exceeds a predetermined value ΔE, it is determined that incomplete combustion has occurred, and the combustion is stopped by closing the solenoid valve in the gas supply line. It is configured.

0003

[Problems to be Solved by the Invention] However, with the above-mentioned conventional incomplete combustion prevention device, when the gas amount is reduced during combustion and the operation is switched to low-load operation, the combustion chamber is damaged. Since the temperature is lower than during full load operation and the electromotive force of the thermocouple is reduced, it is determined that there is incomplete combustion even though it is not, and the gas supply is cut off.
There is a problem that combustion stops.

[0004] Furthermore, even if combustion is incomplete from the start of combustion, the temperature of the combustion chamber in that state is set as the reference temperature, so combustion continues until the electromotive force further decreases by ΔE. There is a problem that incomplete combustion may progress further and lead to an accident.

The present invention solves the above problems and provides an incomplete combustion prevention device that can reliably detect and prevent incomplete combustion even when the gas amount is changed during combustion. The purpose is to provide.

[0006]

[Means for Solving the Problems] In order to achieve the above object, an incomplete combustion prevention device of the present invention includes a gas cutoff valve disposed in a gas supply line to a main burner and a temperature of a combustion chamber. The temperature of the temperature sensor and the combustion chamber that is undergoing steady combustion with a reference gas amount is set as a reference temperature TS, and incomplete combustion occurs when the temperature of the combustion chamber in a steady state of combustion falls by a predetermined temperature range ΔT from the reference temperature TS. If it is determined that combustion is occurring, the gas cutoff valve is operated to stop the gas supply, and if the gas supply amount differs from the standard amount, the temperature of the combustion chamber is changed to a steady combustion state according to the gas supply amount. When the corrected temperature TA is lower than the reference temperature TS by a predetermined temperature range ΔT, incomplete combustion is determined,
It is characterized by comprising a control means for operating the gas cutoff valve to stop the supply of gas.

[0007] Furthermore, the incomplete combustion prevention device of the present invention includes:
In order to detect incomplete combustion from the beginning of combustion, a minimum reference temperature TM is determined in advance, and if the temperature of the combustion chamber does not reach the minimum reference temperature TM, it is determined that incomplete combustion has occurred and the gas is It can also be configured to stop the supply of.

Further, in the incomplete combustion prevention device of the present invention, a thermocouple can be used as the temperature sensor, and incomplete combustion can be detected based on the change in the electromotive force. can.

[0009]

[Operation] The temperature of the combustion chamber in steady combustion with a reference gas amount is set as the reference temperature TS, and incomplete combustion is determined when the temperature of the combustion chamber in the steady combustion state decreases by ΔT from the reference temperature TS, In addition, if the gas supply amount differs from the reference amount, the temperature of the combustion chamber is corrected to the temperature of a steady combustion state according to the gas supply amount, and the corrected temperature TA is within a predetermined temperature range ΔT than the reference temperature TS. Since it is determined that incomplete combustion has occurred when the gas supply amount has decreased, even if the gas supply amount changes, it is possible to detect incomplete combustion according to the gas supply amount.
At that point, the gas cutoff valve can be activated to reliably stop incomplete combustion.

[0010]Furthermore, incomplete combustion from the beginning of combustion is detected by determining a minimum reference temperature TM and assuming that incomplete combustion occurs when the temperature of the combustion chamber does not reach the minimum reference temperature TM. This makes it possible to more reliably prevent incomplete combustion.

Furthermore, by using a thermocouple as a temperature sensor, changes in temperature can be detected based on changes in the electromotive force, and incomplete combustion can be detected.

0012

DESCRIPTION OF THE PREFERRED EMBODIMENTS Examples of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic configuration diagram of a fan heater according to an embodiment of the present invention, and FIG. 2 is a side sectional view of the fan heater. As shown in these figures, a main burner 2 is housed in a case 1, and a combustion chamber 3 is formed above the main burner 2. Below the main burner 2 in the case 1 is a blower fan 4 that blows out hot air.
is installed. Furthermore, a lower high limit switch 5 which is a flashback safety device is provided at the lower part of the main burner 2, and an upper high limit switch 7 and a thermal fuse 8 are provided above the partition plate 6 at the upper part of the combustion chamber 3. is installed. A thermocouple 9 is disposed within the combustion chamber 3 as a temperature sensor for detecting the temperature inside the combustion chamber, and the thermocouple 9 is connected to a control means (control circuit) 10. Further, the gas supply line 11 that supplies gas to the main burner 2 is provided with a proportional valve 12 for adjusting the amount of gas and a gas cutoff valve 13 for cutting off the gas.

The operation of the fan heater (incomplete combustion prevention device) constructed as described above will be explained below with reference to the flowchart of FIG. In the following description of the operation, the temperature T of the combustion chamber 3 and the electromotive force of the thermocouple 9 are proportional and have the same meaning, so the description will mainly be made using temperature.

To operate the fan heater, first, the main burner 2 is ignited. After a certain period of time has elapsed, the temperature T of the combustion chamber 3 (that is, the electromotive force of the thermocouple 9) is measured (step 1), and whether or not the temperature T has reached the minimum reference temperature TM stored in the control means 10 is determined. If the temperature T does not reach TM (step 2), it is determined that the combustion is incomplete from the beginning, and the gas cutoff valve 13 is closed (step 3) to stop combustion. On the other hand, when the temperature T of the combustion chamber 3 rises due to combustion of gas and exceeds the minimum reference temperature TM, the gas cutoff valve 13 is held open (step 4).
) Continue combustion. After a certain period of time, the combustion chamber 3
Measure the temperature T of (step 5), determine whether the temperature T has become almost constant (step 6), and if the temperature T has become constant, set the temperature (electromotive force) to the reference temperature (reference electromotive force) is stored in the control means 10 as TS (step 7
). Then, combustion is continued and it is checked whether the gas amount has been changed (step 8). If the gas amount has not been changed, combustion is continued and the temperature T of the combustion chamber 3 is measured (step 9), and it is determined whether the temperature T has decreased by a predetermined temperature range ΔT or more from the reference temperature TS. (Step 10), for example, when an incomplete combustion state occurs due to a decrease in the oxygen concentration in the air, and the temperature T in the combustion chamber 3 has decreased to a predetermined temperature range ΔT or more, incomplete combustion has occurred. Based on this determination, the gas cutoff valve 13 is closed (step 11) to stop combustion in the main burner 2.

On the other hand, in the case where the gas amount is reduced in the middle of combustion to perform low-load operation, it is confirmed in step 8 that the gas amount has changed, and the temperature T of the combustion chamber 3 measured in step 12 is Difference between the corrected temperature TA multiplied by a predetermined coefficient F according to the gas amount and the reference temperature TS (TS - T x F)
is greater than or equal to a predetermined temperature range ΔT (step 13), and if the value of (TS-T×F) is smaller than the predetermined temperature range ΔT, combustion is continued. On the other hand, in step 13, if (TS - T
stop burning.

[0016] In the above embodiment, the case where the gas supply amount is changed in the direction of decreasing in the middle of combustion has been explained, but the gas supply amount can also be changed in the direction of increasing in the middle of combustion. By applying a coefficient F corresponding to the increase in amount, it is possible to deal with the problem in the same manner as in the above embodiment.

In the above embodiment, a thermocouple 9 is used as a temperature sensor, and the temperature of the combustion chamber 3 is detected by the electromotive force of the thermocouple 9. However, the temperature sensor is not limited to a thermocouple. It is also possible to use other temperature sensors.

Further, in the above embodiment, an incomplete combustion prevention device for a fan heater was explained, but the incomplete combustion prevention device of the present invention can be applied to gas water heaters and other various gas combustion devices. .

[0019]

Effects of the Invention As described above, the incomplete combustion prevention device of the present invention is such that the temperature of the combustion chamber in the steady state of combustion is lower than the reference temperature TS.
If the amount of gas supplied differs from the reference amount, the temperature of the combustion chamber is corrected to the temperature of the steady combustion state, and the corrected temperature T
Since the configuration is such that incomplete combustion is determined and combustion is stopped when A decreases by a predetermined temperature range ΔT from the reference temperature TS, even if the gas supply amount changes, the combustion will be stopped accordingly. Incomplete combustion can be detected and can be reliably prevented.

[0020] In addition, incomplete combustion from the beginning of combustion can be prevented by determining a minimum reference temperature TM, and when the temperature of the combustion chamber does not reach the minimum reference temperature TM, it is regarded as incomplete combustion and combustion is stopped. This makes it possible to detect incomplete combustion more reliably.

Furthermore, when a thermocouple is used as a temperature sensor, a change in temperature can be detected based on a change in the electromotive force, and incomplete combustion can be easily detected.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a schematic configuration of a fan heater equipped with an incomplete combustion prevention device according to an embodiment of the present invention.

FIG. 2 is a side sectional view of a fan heater equipped with an incomplete combustion prevention device according to an embodiment of the present invention.

FIG. 3 is a flowchart for explaining the operation of the incomplete combustion prevention device according to an embodiment of the present invention.

[Explanation of symbols]

2 Main burner 3 Combustion chamber 9 Thermocouple (temperature sensor) 10
Control means 11 Gas supply line 13 Gas cutoff valve

Claims (3)

[Claims] Claim 1: A gas cutoff valve disposed in a gas supply line to a main burner, a temperature sensor that detects the temperature of the combustion chamber, and a temperature of the combustion chamber that is steadily burning at a reference gas amount as a reference temperature TS. When the temperature of the combustion chamber in the steady combustion state drops by a predetermined temperature range ΔT from the reference temperature TS, incomplete combustion is determined, and the gas cutoff valve is operated to stop the gas supply. , if the gas supply amount differs from the reference amount, the temperature of the combustion chamber is corrected by converting it to the temperature in a steady combustion state according to the gas supply amount, and the corrected temperature T
The present invention is characterized by comprising a control means that determines that incomplete combustion has occurred when the temperature A decreases by a predetermined temperature range ΔT from the reference temperature TS, and operates the gas cutoff valve to stop the supply of gas. Incomplete combustion prevention device. 2. In order to detect incomplete combustion from the beginning of combustion, a minimum reference temperature TM is determined in advance, and if the temperature of the combustion chamber does not reach the minimum reference temperature TM, incomplete combustion is determined. 2. The incomplete combustion prevention device according to claim 1, wherein the incomplete combustion prevention device determines whether or not the gas is present and closes the gas cutoff valve to stop the gas supply. 3. The incomplete combustion prevention device according to claim 1, wherein the temperature sensor is a thermocouple and detects incomplete combustion based on a change in the electromotive force thereof.