JPS63105317A - Combustion apparatus - Google Patents

Abstract

PURPOSE:To enable combustion to be terminated before a concentration of oxygen is reduced by a method wherein a thermocouple element is placed through a holding pipe at a downstream side from an auxiliary air hole made in a wall of combustion chamber near a burner and at the same time a part of the holding pipe is provided with a bypass hole. CONSTITUTION:A part of a holding pipe 4 is provided with a bypass hole 7. In a normal combustion, air flowing from the holding pipe 4 of a thermocouple element 5 and an auxiliary air hole 6 may contribute as combustion air when premixture gas having a low air ratio performs a first stage combustion and so a got thermoelectromotive force value is also high. In urn, in an abnormal condition such as an input-down under a weak combustion or a low concentration of oxygen, air flowing from an auxiliary air hole 6 and the holding pipe 4 may break a flame plane to be formed, eliminate a flame and cool the thermocouple element 5 placed adjacent within the combustion chamber 3, with the result that a got thermoelectromotive force value is also reduced. As a result, it may be detected stably before a concentration of CO is rapidly increased or before it is lower than a specified concentration of oxygen due to a variation of a thermoelectromotive force value when a combustion is transferred to its abnormal condition.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to the prevention of incomplete combustion in combustion devices for space heaters such as stoves and fan heaters.

BACKGROUND OF THE INVENTION Conventionally, this type of indoor open type heater has a burner 2, a thermocouple element 6, and auxiliary air in a combustion chamber 3, as shown in FIG. 6, in order to maintain the cleanliness and safety of the indoor environment. A hole e is provided, and a certain detection level (threshold) is set based on the signal characteristics of the thermocouple element 6 during incomplete combustion, and the quality of the combustion state is determined by the detection level and the signal from the thermocouple element 5 Judgment is made by comparing with the signal.

Problems to be Solved by the Invention In the above configuration, compared to the signal changes of the thermocouple element 6 such as input (combustion amount) fluctuations and voltage fluctuations during weak combustion, as shown in FIG. Carbon monoxide (CO) may increase significantly and the value of the evaluation value CO/Co2 may increase rapidly. Furthermore, when combustion occurs when the indoor oxygen concentration decreases, the Co/CO2 value in the exhaust gas increases, or even if the co7c○2 value does not increase, breathing becomes difficult in a heated room. There is.

On the other hand, if we take into account the dispersion of the signal from the thermocouple element 6 (due to the performance of the thermocouple element 6 itself or 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 to a low level. However, if this is done, even if the CO concentration in the exhaust gas increases rapidly, it will not be detected and combustion will continue, leading to the possibility of poisoning symptoms due to the high concentration of CO emissions, or breathing difficulties due to lack of oxygen. There is.

The present invention solves such conventional problems by increasing the signal change of the thermocouple element especially when the input is down, the voltage fluctuates, and when the oxygen concentration decreases, and the indoor The present invention provides a combustion device equipped with a safety device that stops combustion before the oxygen concentration decreases.

Means for Solving the Problems In order to solve the above problems, the combustion apparatus of the present invention includes a burner in the combustion chamber, an auxiliary air hole in the wall of the combustion chamber near the burner, and a thermocouple element via a holding pipe on the downstream side. At the same time, a bypass hole is provided in a part of the holding pipe, or the bypass hole is provided facing upstream.

Function: With the above configuration, air flows into the combustion chamber through the auxiliary air hole and the holding pipe and contributes to combustion. Therefore, although it contributes to combustion during steady combustion (strong to weak combustion), under abnormal conditions such as input down during weak combustion or weak combustion under low oxygen concentration, the flame front that forms near the auxiliary air holes. and at the same time cool the thermocouple element facing into the combustion chamber. As a result, a large output can be obtained during steady combustion, and a small output can be obtained during abnormal combustion. Then, a characteristic showing a large gradient of change as shown in FIG. 4 is obtained, and it becomes possible to set a detection level for variations without risk of malfunction. Therefore, even if there is a sudden increase in Co in the exhaust gas (for example, an abnormal input drop due to port breakage) or if the oxygen concentration drops significantly and breathing becomes difficult, it will be detected immediately and combustion will be stopped. can do.

EXAMPLE Hereinafter, an example of the present invention will be described based on FIGS. 1 to 6.

A burner 2 having a large number of flame holes 1 in FIGS. 1 to 6
is provided in the combustion chamber 3, and a thermocouple element 5 and an auxiliary air hole 6 are provided in the vicinity of the burner 2 from the wall surface of the combustion chamber 3 via a holding pipe 4, respectively. A bypass hole 7 is provided in a part of the holding pipe 4. The above-described configuration forms the first stage combustion region 8. Further, the casing 9 covers the outer periphery of the combustion chamber 3 to form an air passage 10 and at the same time constitutes a second stage combustion region 11. Furthermore, a detection circuit (not shown) and a comparison circuit (not shown) are sequentially connected to the thermocouple element 6, and the comparison circuit is a solenoid valve (not shown) that opens and closes the fuel supply.
It is connected to a drive circuit (not shown) for driving. In the comparison circuit, a comparison is made based on the difference between the thermoelectromotive force value (Ei) obtained by the thermocouple element 6 and the set detection level (E8), and a signal is output to the drive circuit.

With the above configuration, during steady combustion ranging from strong combustion to weak combustion, the air flowing into the combustion chamber 3 from the holding pipe 4 of the thermocouple element 6 and the auxiliary air hole 6 is premixed with a low secondary air ratio. The thermoelectromotive force value (E2) that can be obtained by contributing as combustion air when performing eye combustion 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 hole 6 and the holding pipe 4 destroys the flame surface that is formed and extinguishes the flame. Furthermore, the thermocouple element 6 facing into the combustion chamber 3 is cooled, and the obtained thermoelectromotive force value is also reduced.

As a result, the change in thermoelectromotive force value obtained when combustion transitions from a steady state to an abnormal state becomes large, as shown in Figure 4, and the detection level can be set stably and before the CO concentration suddenly increases. Furthermore, stable detection is possible before the oxygen concentration drops to a certain level. Therefore, a combustion device with high safety can be obtained.

FIG. 6 relates to a second embodiment of the present invention, which differs from the first embodiment only in that the bypass hole 7 is provided facing the upstream side of the flow, and the operation is the same as the first embodiment. By providing the bypass hole toward the upstream side, the effect is further increased.

Effects of the Invention As described above, according to the combustion apparatus of the present invention, a thermocouple element is installed in the burner in the combustion chamber and on the combustion chamber wall near the burner through the auxiliary air hole and the holding pipe, and the holding pipe is connected to the burner. Since a bypass hole is provided in the section, it increases the change in the signal obtained from the thermocouple element and prevents a sudden increase in the Co concentration in abnormal combustion conditions (input down due to a broken fuel supply hose, etc., or combustion under low oxygen concentration). This provides a highly safe combustion device that stably stops combustion at a set detection level before breathing becomes difficult.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view of a combustion device which is an embodiment of the present invention;
Fig. 2 is a partial enlarged sectional view of Fig. 1 showing the structure near the combustion chamber, Fig. 3 is a characteristic diagram showing the relationship between combustion amount, CO/CO2, and thermoelectromotive force value obtained by a thermocouple element; Fig. 4 is a characteristic diagram showing the relationship with the thermoelectromotive force value when oxygen production is reduced, Fig. 5 is a partially enlarged sectional view showing the structure near the holding pipe in the second embodiment of the present invention, and Fig. 6 is a FIG. 2 is a partially enlarged cross-sectional view showing the configuration of a conventional combustion chamber. 2...Burner, 3...Combustion chamber, 4...
...Holding pipe, 6...Thermocouple element, 6.
...Auxiliary air hole, 7...Bypass hole. Name of agent: Patent attorney Toshio Nakao and 1 other person1-
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Claims (2)

[Claims] (1) In the combustion chamber, a burner and an auxiliary air hole are installed in the combustion chamber wall near the burner, and a thermocouple element is installed downstream of the auxiliary air hole via a holding pipe, and a part of the holding pipe is provided. A combustion device with a bypass hole. (2) The combustion device according to claim 1, wherein the bypass hole of the holding pipe is provided facing upstream.