JPH0754179B2 - Combustion safety device - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for preventing incomplete combustion of a combustion device for a heater such as a stove and a fan heater.

2. Description of the Related Art Conventionally, in order to maintain the cleanliness and safety of the indoor environment, this type of indoor open type heater has a burner 2, a thermocouple 5, and an auxiliary air hole in the combustion chamber 3 as shown in FIG. 6 is installed in advance, and a constant detection level (threshold value) is set based on the signal characteristics of the thermocouple 5 at the time of incomplete combustion. Whether the combustion state is good or bad is determined by this detection level and the signal from the thermocouple 5. Compare and judge.

Problems to be Solved by the Invention In the above-mentioned configuration, although the incomplete combustion state is reliably determined, the signal from the thermocouple 5 such as when the input (combustion amount) fluctuates during weak combustion and the voltage fluctuates. Compared to the change, as shown in Fig. 2, carbon monoxide (CO) in the exhaust gas may remarkably increase and the value of CO / CO ₂ may sharply increase. on the other hand,
Considering the variation of the signal from the thermocouple 5 (due to the performance of the thermocouple itself, the mounting position, etc.), the difference between the steady level and the detection level must be increased to prevent malfunction. Therefore, it is necessary to set the detection level low. However, if only the detection level is set low with such characteristics, even if the CO concentration in the exhaust gas suddenly increases, combustion cannot be detected and combustion may continue, and poisoning symptoms due to high concentration CO emission may occur. , Or may have dyspnea due to lack of oxygen.

The present invention solves such a conventional problem, in particular, by increasing the signal change of the thermocouple at the time of input down, voltage fluctuation, and oxygen concentration decrease, before the CO concentration sharply increases, and further, the oxygen concentration in the room remains constant. The present invention provides a combustion device having a safety device that stops combustion before it decreases.

Means for Solving the Problems In order to solve the above problems, a combustion apparatus of the present invention is provided with a bottomed combustion chamber, a burner provided at the bottom of the combustion chamber, and a combustion chamber bottom near the burner. A supplementary air hole, a thermocouple inserted into the flame formed on the flame hole while facing the combustion chamber above the supplementary air hole, and directly below the thermocouple, and relative to the lower end of the flame. And a hole provided at a position to be formed.

Action With the above configuration of the present invention, air flows into the combustion chamber through the auxiliary air holes and the holes (auxiliary holes) and contributes to steady combustion. However, under an abnormal condition such as an input down in weak combustion or a low oxygen concentration, the ratio of the air amount of the air flowing in from the hole (auxiliary hole) to the amount of the premixed gas forming the flame becomes unbalanced. Air flowing from the holes (auxiliary holes) locally destroys and cools the flame formed near the holes (extinguishing action), and at the same time, cools the thermocouple facing the combustion chamber immediately above. As a result, a large output is obtained in steady combustion, and a small output is obtained in abnormal combustion. Then, a characteristic showing a large output signal change gradient as shown in FIGS. 2 and 3 can be obtained, and it becomes possible to set the detection level with respect to variations without risk of malfunction.

Therefore, even if a rapid increase in CO in exhaust gas occurs (for example, input down due to a hose break) or even if breathing becomes difficult due to a significant decrease in oxygen concentration, it is possible to detect combustion immediately and stop combustion immediately. it can.

Embodiment An embodiment of the present invention will be described below with reference to FIGS. 1 to 3.

A burner 2 having a large number of flame holes 1 in FIGS. 1 to 3.
Is provided in the combustion chamber 3, and a thermocouple 5 and an auxiliary air hole 6 are respectively provided from the wall surface of the combustion chamber 3 to the vicinity of the burner 2 via a holding pipe 4. An auxiliary hole 7 is provided on the wall surface of the combustion chamber 3 directly below the thermocouple 5 and between the thermocouple 5 and the auxiliary air hole 6. With the above configuration, the first-stage combustion region 8 is formed. Further, the casing 9 covers the outer periphery of the combustion chamber 3 while the air passage is provided.
At the same time when 10 is formed, the second combustion region 11 is formed. Further, a detection circuit (not shown) and a comparison circuit (not shown) are sequentially connected to the thermocouple 5, and the comparison circuit drives an electromagnetic valve (not shown) for opening and closing the fuel supply. Drive circuit (not shown). In the comparison circuit, the thermoelectromotive force value (E
_i ) and the set detection level (E _s ) are compared and judged, and a signal is output to the drive circuit.

With the above configuration, during steady combustion from strong combustion to weak combustion, the air flowing into the combustion chamber 3 from the auxiliary air holes 6 and 7 when the premixed air with a low primary air ratio performs the first-stage combustion. Contributes as combustion air, and the obtained thermoelectromotive force value (E ₂ ) is also large. On the other hand, under abnormal conditions that may occur such as input down under weak combustion or weak combustion under low oxygen concentration, the air flowing in from the auxiliary air holes 6 is used as combustion air and forms a large flame surface on the upper side. However, the air flowing in from the auxiliary holes 7 partially destroys and cools the formed flame surface, and also cools the thermocouple 5 immediately above. As a result, the change in the thermoelectromotive force value obtained when the combustion transitions from the steady state to the abnormal state becomes large as shown in FIGS. 2 and 3, and the detection level can be set stably and the CO concentration sharply increases. Further, stable detection can be performed before the oxygen concentration becomes constant. Therefore, a highly safe combustion device can be obtained.

As described above, according to the combustion apparatus of the present invention, the burner at the bottom of the bottomed combustion chamber, the auxiliary air hole in the combustion chamber wall near this burner, and the auxiliary hole (hole) at the upper part of this auxiliary air hole Furthermore, since the thermocouples are installed directly above the auxiliary holes in the combustion chambers respectively, the signal change obtained from the thermocouples is increased to cause an abnormal combustion state (input down due to breakage of the hose for fuel supply, etc. or under low oxygen concentration). Before the rapid increase in CO concentration
Alternatively, the fuel can be stopped stably at the set detection level before the user has difficulty breathing in the low O ₂ state.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of a combustion apparatus according to an embodiment of the present invention,
2 is a characteristic diagram showing the relationship between the combustion amount, CO / CO ₂ and the thermoelectromotive force value obtained by the thermocouple, and FIG. 3 is a characteristic diagram showing the relationship between the thermoelectromotive force value when the oxygen concentration decreases, FIG. 4 is a partially enlarged cross-sectional view showing the structure of the conventional combustion chamber. 2 ... Burner, 3 ... Combustion chamber, 5 ... Thermocouple, 6 ... Auxiliary air hole, 7 ... Hole (auxiliary hole).

Claims (1)

[Claims] 1. A combustion chamber having a bottom, a burner provided at the bottom of the combustion chamber, an auxiliary air hole provided at the bottom of the combustion chamber near the burner, and an upper part of the auxiliary air which faces the combustion chamber. A combustion safety device comprising a thermocouple inserted into the flame formed on the flame hole and a hole provided directly below the thermocouple and facing the lower end of the flame.