JPS5852913A - Combustion safety apparatus - Google Patents

Abstract

PURPOSE:To perform the combustion detection of ignition or misfire and the incomplete combustion detection so as to control the combustion, by carrying out the combustion control about an ionic current through a flame rod by first and second setting values. CONSTITUTION:A certain voltage is energized to the flame rod 8 by a control circuit 15, and an ionic current is passed immediately when it is ignited by an ignition plug 9. The first set value (a) is set at a value smaller than the ionic current value that will be passed at the normal combustion, and when it is at this value or below, the control circuit 15 controls the gas valve 12 to be closed. Further when atmospheric oxygen concentration is low, the second setting value (b) is set higher than the first set value (a) and lower than a peak value (c), and when an ionic current higher than the second set value (b) is passed, the control circuit 15 closes the gas valve 12. Thus, the combustion detection of ignition or misfire, or the incomplete combustion state detection which will be done when the atmospheric oxygen concentration becomes low, or a primary air inlet is closed, or the exhaust gas is confined, will be carried out to control the combustion.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a safety device for heating appliances such as stoves using premixed surface combustion burners. The purpose is to provide a combustion safety device that controls combustion.

Conventional combustion safety devices that perform premixed surface combustion, such as Schbank burners and wire mesh burners used in stoves, have used ZrO2 sensors, oxygen concentration difference sensors, and oxygen partial pressure sensors. These sensors have disadvantages such as high cost, poor responsiveness to ignition and misfire detection, and the need for separate combustion detection means.

On the other hand, a method of detecting incomplete combustion by installing a flame rod in the flame and using the phenomenon of flame floating during oxygen deficiency has also been proposed.
Although this method has excellent responsiveness, it utilizes the characteristic that the ion current decreases as the atmospheric oxygen concentration decreases, as shown in curve B in Figure 2, and is important for Bunsen combustion and all secondary combustion. It was getting worse.

The reason for this is that in those that perform premixed surface combustion,
One possible method is to provide a flame rod near the tip of the flame, but since the tip of the flame in a Bunsen burner or the like is unstable, the ion current value is not stabilized, causing malfunction. On the other hand, in premixed surface combustion, it was not known that when a flame rod is installed near the flame tip, the ion current increases when incomplete combustion occurs compared to the stalled combustion state. Because the value was small, it was thought that the ion current would further decrease in incomplete combustion conditions, and that the value would be too small to be detected.

Therefore, as a safety device against incomplete combustion in a combustion appliance that performs premixed surface combustion, the ion current detection means using a flame rod is not used, but the Z rO2 sensor oxygen sensor is used.

In the present invention, in a device that performs premixed surface combustion, by providing a flame rod near the tip of the flame that is in close contact with the surface, the ion current increases when the oxygen concentration decreases or the primary air port becomes clogged. The purpose is to provide a combustion safety device that utilizes these characteristics to detect combustion in the event of ignition or misfire, as well as to detect incomplete combustion.

An embodiment of the present invention will be described below with reference to FIGS. 1 and 2.

FIG. 1 is a side sectional view showing an embodiment in which the combustion safety device of the present invention is used in a hot air heater.

1 in the figure is a cylindrical wire mesh burner that performs premixed surface combustion.
Mixture inlet 2, mixing pipe 3, mixture chamber 4, wire mesh crater 6
, an outer cylinder part 6, and a combustion chamber 7.

A flame rod 8 is installed near the flame port 6 that performs premixed surface combustion.
, a spark plug 9 are provided, and a pressure equalizing plate/catalyst body 11 is provided in an exhaust passage 10 downstream of the combustion chamber 7.

On the other hand, the fuel gas passes through the gas valve 12 and the pressure regulator 13 and is ejected from the gas nozzle 14 to the air-fuel mixture suction port 2 .

A control circuit 15 controls the gas valve 12, the igniter, and the blower 16, and detects the ionic current flowing through the flame rod 8 to control combustion.

17 is an air blow control board, 18 is a hot air i+fz path, and 19 is a hot air outlet.

In the above configuration, the fuel ejected from the gas nozzle 14 sucks the surrounding air as primary air, flows into the mixture chamber 4, and performs surface combustion in the wire gauze flame hole portion 6.

Near the tip of the flame V in close contact with the flame nozzle 6 that performs surface combustion
A flame rod 8 is provided (a constant voltage is applied by the moss control circuit 16, and when the spark plug 9 is ignited, an ionic current flows instantaneously), as shown in FIG.
The first set value a is set to a value smaller than the value of the ion current flowing during normal combustion, and if the value is higher than that, combustion will continue; , to close the gas valve 12? Since it is controlled by the l+lI control circuit 16, ignition and misfire detection are performed.

In other words, when the atmospheric oxygen concentration decreases, the amount of oxygen in the premixture also decreases, so the flame that was performing surface combustion in the wire mesh flame nozzle 6 stretches out as the oxygen concentration decreases, completely destroying the flame rod 8. It becomes like covering it.

When the oxygen concentration further decreases, a phenomenon occurs in which the flame floats up from the wire mesh flame opening 6. Therefore, the ion current increases as the oxygen concentration decreases as shown in the curve, reaches a peak value just before the flame rises, and then rapidly decreases. Now, the second set value is set to be larger than the first set value a and smaller than the peak value C, and the control circuit 16 closes the gas valve 12 when an ion current exceeding the second set value flows. .

On the other hand, in the combustion state, when the flame starts to rise, the V
Although the generation of harmful gases such as o and HCHO increases, the second set value can be detected before that.

Although FIG. 2 relates to a time when the atmospheric oxygen concentration is low, when the primary air port is clogged, the primary air suction area is decreased, so the situation is exactly the same as when the oxygen concentration is low. Furthermore, even during so-called exhaust blockage when the blow-off port 19 is blocked, the amount of air blown by the blower 16 decreases, and the combustion gas suction force decreases due to the air blowing, resulting in a situation that is exactly the same as a primary air shortage.

The method for controlling combustion has been described above in which the control circuit 16 uses the first set value d and the second set value, but the second set value d is the peak value immediately before the flame rises from the flame opening. It is also possible to perform combustion control by detecting C and detecting an incomplete combustion state.

As is clear from the above description, the combustion safety device of the present invention is capable of controlling ion ions by the phenomenon that in premixed surface combustion, the flame grows as the oxygen meter in the premixture decreases, and when the oxygen meter in the premixture decreases further, the flame rises to the surface. Since this method utilizes the characteristic that the current increases, reaches a peak value, and then decreases, the ion flow by the flame rod is detected and the first. By controlling combustion using the second set value, combustion can be controlled by detecting ignition or misfire, or by detecting incomplete combustion when the atmospheric oxygen concentration drops, when the primary air port is clogged, or when the exhaust is blocked. I can do it.

Therefore, even in devices that perform premixed surface combustion, it is possible to provide a combustion safety device that detects incomplete combustion using the flame rod. Detection response is fast,
No separate means for combustion detection is required. Furthermore, Zro
It is superior in durability and reliability compared to 2 sensors, etc., and
It is also excellent in terms of cost.

[Brief explanation of the drawing]

FIG. 1 is a side cross-sectional view showing one embodiment of the combustion safety device of the present invention, and FIG. 2 is a characteristic diagram showing the ionic current of the combustion safety device when the atmospheric oxygen concentration decreases. 1----... Burner, 6-- ■ [Co., Ltd.] Enokuchibe, 8-
...... Frame rod, 16... Control circuit, a... First set value, b... Second set value, C...・Peak value. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 2

Claims (1)

[Claims] A flame rod is installed near the flame tip that is in close contact with the flame opening of the bath that performs premixed surface combustion, and the ion flow flowing to the flame rod is detected and ignited at the first set value, resulting in combustion in the event of a misfire. Detecting incomplete combustion at a second set value or peak value that is larger than the first set value,
A combustion safety device equipped with a control circuit that controls combustion.