JP4547555B2 - Incomplete combustion prevention device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an incomplete combustion preventing device used for a gas combustion appliance such as a fan heater.
[0002]
[Prior art]
Gas combustion appliances, such as fan heaters, can detect in advance and supply gas when indoor ventilation is inadequate because the oxygen concentration in the room is low and incomplete combustion may occur. An incomplete combustion prevention device (hereinafter abbreviated as non-combustion prevention device) is provided.
Specifically, a thermocouple is installed near the burner of the fan heater, and the electromotive force obtained here is directly used to hold the magnet solenoid valve provided in the gas flow path, or the controller that controls opening and closing of the magnet solenoid valve It is the composition which makes it monitor. As a result, when the oxygen concentration in the room decreases, the electromotive force of the thermocouple decreases due to the lift or extinguishing of the burner flame, so the magnet solenoid valve is closed directly or via the controller to supply gas. Will be cut off. In such a non-combustion preventive device, the electromotive force of the thermocouple is about the same when the capacity is high and when the capacity is low, and has a characteristic that changes greatly between normal combustion and oxygen shortage. preferable.
[0003]
Conventionally, as a burner used for a fan heater, in order to reduce NOx, a flame hole plate having a large number of slit-shaped primary flame holes is attached to the upper part of the burner body, and the upper surface thereof is covered with a box. A secondary combustion is formed by forming a primary combustion chamber and opening a secondary flame hole on the upper surface of the box, and dividing the combustion into a primary combustion performed in the primary flame hole and a secondary combustion performed in the secondary flame hole A method is known. And the thermocouple of a nonflammable prevention apparatus is installed in the vicinity of the slit-shaped primary flame hole 70 where such burner primary combustion is performed, as shown in FIGS. 7 is a top view of the flame hole plate 30 provided with a large number of slit-shaped primary flame holes 70, and FIGS. 8 and 9 are cross-sectional views taken along one-dot chain line BB.
In such a non-combustible device, when the thermosensitive portion 140a of the thermocouple 140 is installed directly above the flame formed in the slit-shaped primary flame hole 70, an appropriate electromotive force is obtained when the capacity is large as shown in FIG. When the capacity is low, as shown in FIG. 9, the heat sensitive part 140a enters the outer flame film, but the electromotive force that can be separated from the flame is reduced. Further, when installed at the position (B) where an appropriate electromotive force can be obtained when the capacity is small, as shown in FIG. 8, when the capacity is large, the heat-sensitive part 140a enters the inner part (flame core) of the low-temperature internal flame. Therefore, only low electromotive force can be obtained. Therefore, by shifting the thermocouple 140 from the position (B) to the outside of the flame (on the left side in FIGS. 8 and 9), the side surface portion of the flame with little change in the magnitude of the flame between when the ability is large and when it is small That is, the thermocouple 140 is installed on the side surface portion of the flame which is located outside the low temperature flame core and is always a high temperature portion.
[0004]
[Problems to be solved by the invention]
However, since the high-temperature outer flame and inner flame portion are narrow, there has been a problem that the electromotive force of the thermocouple fluctuates due to a slight fluctuation of the flame. In addition, since variations in electromotive force due to assembly errors become large, the manufacturing process must be managed very strictly.
In addition, even if lifted when oxygen is insufficient, the thermocouple is provided above the flame formed in the slit-shaped primary flame hole 70, so that the thermocouple is heated to some extent, and the electromotive force is gradually reduced. There was also a problem.
The incomplete combustion preventing device of the present invention solves the above-mentioned problem, and in the entire gas amount adjustment range from high capacity to low capacity, an appropriate electromotive force of the thermoelectric element is obtained, and the electromotive force is generated when oxygen is insufficient. The goal is to change quickly and drastically.
[0005]
[Means for Solving the Problems]
The incomplete combustion preventing apparatus according to claim 1 of the present invention for solving the above-mentioned problems is provided.
A burner provided with a flame hole plate in which a series of flame holes in which a large number of slit flame holes are arranged linearly in the longitudinal direction, and a thermoelectric element heated by the flame of the burner,
In the incomplete combustion preventing device for detecting incomplete combustion of the burner based on the electromotive force obtained from the thermoelectric element,
The central portion of the flame hole plate in which the flame hole array is arranged is lifted to form a step portion along the longitudinal direction, and the slit flame hole is opened from the upper surface to the side surface of the step portion. The gist is to spread the flame formed in the flame hole in the lateral direction, and to provide the heat-sensitive portion of the thermoelectric element at a position heated by the side surface of the flame expanded in the lateral direction.
[0006]
The incomplete combustion preventing apparatus according to claim 1 of the present invention having the above-described configuration lifts the central portion of the flame hole plate to form a step portion along the longitudinal direction, and slit flame extends from the upper surface to the side surface of the step portion. By opening the hole, the flame formed in the slit flame hole is expanded in the lateral direction. That is, the high temperature external flame and the internal flame part located on the outer surface of the flame core having a low flame temperature are widened laterally. Thus, by providing the heat sensitive part of the thermoelectric element on the side surface of the flame where the high temperature part is widened, it is possible to obtain a stable and suitable electromotive force from when the capacity is high to when the capacity is low.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
In order to further clarify the configuration and operation of the present invention described above, a preferred embodiment of the incomplete combustion preventing apparatus of the present invention will be described below.
[0008]
FIG. 1 is a schematic cross-sectional view of a gas burner (a cross section taken along one-dot chain line A-A in FIGS. 2 and 3), FIG. 2 is a front view of the gas burner with a part cut away, and FIG. It is a top view of the flame hole board provided.
The burner 1 is a gas burner that is used in a gas fan heater and that reduces NOx by two-stage combustion. The burner 1 includes a burner body 2, a flame hole plate 3, and a box 4.
[0009]
The burner body 2 is formed with a mixing pipe 5 for mixing the fuel gas and the primary air, and an inlet 6 through which the fuel gas and the primary air are sucked opens at the base end of the mixing pipe 5. Yes. A flange portion 10 extending in the horizontal direction is formed on the upper portion of the burner body 2, and a flame hole plate 3 having a large number of slit-like primary flame holes 7 is attached to the flange portion 10 by spot welding.
A box 4 is provided at the top of the flame hole plate 3 so as to cover the primary flame hole 7, and a primary combustion chamber 9 is formed inside the box 4. In order to supply secondary air to the primary combustion chamber 9, a plurality of air holes 11 penetrating the flange 10 of the burner body 2 and the flame hole plate 3 are provided around the primary flame hole 7. A rectangular secondary flame hole 12 is opened on the upper surface of the box 4.
[0010]
The flame hole plate 3 is formed with a step portion 16 including a top surface 16a that is a horizontal surface and a side surface 16b that is an inclined surface along the longitudinal direction by lifting the central portion from the surrounding horizontal plane portion 17 by pressing. The And in this step part 16, many slit-shaped primary flame holes 7 are arranged in two rows before and after the first flame hole row 18a on the front side and the second flame hole row 18b on the back side, The primary flame holes 7 are arranged in groups of four at a predetermined pitch to form the block flame holes 8, and the block flame holes 8 have a length shorter than the possible flame transfer distance. A flameless hole 13 is provided.
Each primary flame hole 7 of the first flame hole row 18a is opened from the vicinity of the center of the upper surface 16a of the step portion 16 to the inclined surface 16b on the near side, and each primary flame hole 7 of the second flame hole row 18b is formed on the step portion. 16 is opened from the vicinity of the center of the upper surface 16a to the inclined surface 16b on the back side. By opening in this way, gas is ejected in a substantially horizontal direction from the outer end portion 7 a formed on the side surface 16 b of the step portion 16 of the slit-shaped primary flame hole 7, and the flame formed in the primary flame hole 7. Spreads horizontally.
[0011]
The rightmost block flame hole in FIG. 3 of the flame hole plate 3 is formed by nine primary flame holes 7, and an ignition electrode (not shown) is provided thereabove. In other words, two block flame holes 8 composed of four primary flame holes 7 are combined to form a large block flame hole without the flameless hole portion 13 therebetween, so that the flame is surely ignited by a spark from the ignition electrode. I have to.
Further, a thermocouple 14 as a thermoelectric element is placed on the side surface of the box body 4 from the outside of the box body 4 at a position heated to the side surface of the flame formed in the third flame hole hole 8 from the right of the first flame hole row 18a. It is provided by being inserted into a thermocouple mounting hole 15 that is opened to the outside. The thermocouple 14 is connected to a controller (not shown). When the electromotive force obtained from the thermocouple 14 is greater than or equal to a predetermined value, the controller energizes and holds the magnet electromagnetic valve provided in the gas flow path, and when the obtained electromotive force falls below the predetermined value, the magnet electromagnetic Incomplete combustion is prevented by stopping energization and shutting off the gas supply. In FIG. 2, the thermocouple 14 is omitted.
[0012]
In the burner 1 having the above-described configuration, fuel gas is ejected from a gas nozzle (not shown) to the mixing pipe 5 of the burner body 2 through the suction port 6, and the air necessary for combustion as primary air from the suction port 6 is accompanied by the ejection. Part of is captured. The fuel gas mixed with the primary air in the mixing tube 5 in this manner is ejected from the upper part of the burner body 2 through the primary flame hole 7 of the flame hole plate 3 and ignited by the ignition electrode. The flame ignited by the ignition electrode moves well between the block flame holes 8 over the entire flame hole surface.
Secondary air is sucked into the primary combustion chamber 9 from the air holes 11 and used for primary combustion. Since the air holes 11 are formed so that the sucked secondary air is less than the air necessary for the combustion, the primary combustion is an oxygen-deficient combustion, and the combustion is completed in the primary combustion chamber 9. Instead, unburned components are ejected from the secondary flame holes 12 provided in the box body 4, and secondary air is sucked from around the secondary flame holes 12 to perform secondary combustion. By performing the two-stage combustion in this manner, the flame temperature can be lowered and the amount of NOx generated can be suppressed.
[0013]
Next, detection of incomplete combustion of the burner 1 by the thermocouple 14 will be described. As shown in FIGS. 4 and 5, gas is ejected in a substantially horizontal direction from the outer end portion 7 a of the slit-shaped primary flame hole 7 opened in the side surface 16 b of the step portion 16 of the flame hole plate 3. The flame spreads in the lateral direction, and the high-temperature outer flame and inner flame portion located on the outer surface of the flame core having a low flame temperature become wider. And the thermocouple 14 is attached so that the heat sensitive part 14a may come to the side surface of the flame which the high temperature part became wide in this way. For this reason, the thermosensitive portion 14a of the thermocouple 14 has an external flame that is a high-temperature portion even if the flame is somewhat fluctuated in all gas amount adjustment ranges from the large capacity shown in FIG. 4 to the small capacity shown in FIG. Fully heated by internal flame. That is, a stable and appropriate electromotive force can be obtained from the thermocouple 14 in all gas amount adjustment ranges from large capacity to small capacity.
[0014]
Then, when the indoor ventilation is insufficient or the indoor oxygen concentration decreases, the flame formed in the primary flame hole 7 starts to lift. In this case, as shown in FIG. 6, the secondary air taken from around the primary flame hole 7 starts to lift from the vicinity of the outer end 7 a of the primary flame hole 7. Therefore, a flame can be quickly heard from around the thermocouple 14 installed in that portion. As a result, since the electromotive force decreases rapidly due to the lack of oxygen, incomplete combustion can be detected with high sensitivity.
[0015]
When the electromotive force obtained from the thermocouple 14 decreases due to flame lift or extinction, the controller determines that incomplete combustion has occurred, and closes the magnet solenoid valve provided in the gas flow path to the burner 1. Thus, a non-combustible device that shuts off the gas supply works.
[0016]
Although the embodiment of the present invention has been described above, the present invention is not limited to such an embodiment, and it is needless to say that the present invention can be implemented in various modes without departing from the gist of the present invention.
For example, the incomplete combustion preventing device of the present embodiment has been described for a gas burner for two-stage combustion for a fan heater. Applicable.
In addition, the electromotive force obtained from the thermocouple 14 is input to the controller, and the magnet electromagnetic valve is energized from the controller to hold the valve open. The valve may be energized.
[0017]
【The invention's effect】
As described above in detail, according to the incomplete combustion preventing device according to claim 1 of the present invention, in the entire gas amount adjustment range from the large capacity to the small capacity, it is possible to stably and appropriately remove the thermoelectric element during normal combustion. Therefore, it can be used with high reliability without malfunction. In addition, since the electromotive force is quickly reduced with respect to the lift, incomplete combustion can be detected with high sensitivity, and it can be used more safely.
In addition, since a certain margin is generated at the thermoelectric element mounting position, it is not necessary to perform so strict management in the manufacturing process for mounting the thermoelectric element, so that the manufacturing cost can be reduced.
[Brief description of the drawings]
FIG. 1 is a schematic cross-sectional view of a gas burner of an embodiment.
FIG. 2 is a front view of the gas burner of the present embodiment in a partially cutaway state.
FIG. 3 is a top view of a flame hole plate of the gas burner of the present embodiment.
FIG. 4 is an explanatory diagram of the shape of the flame formed in the primary flame hole when the thermocouple mounting position and capacity of the present embodiment are large.
FIG. 5 is an explanatory diagram of the shape of the flame formed in the primary flame hole when the thermocouple mounting position and capacity of the present embodiment are small.
FIG. 6 is an explanatory diagram showing the shape of a flame near the thermocouple during lift.
FIG. 7 is a top view of a flame hole plate of a conventional gas burner.
FIG. 8 is an explanatory diagram of the shape of a flame formed in the primary flame hole when the thermocouple mounting position and capacity of a conventional example are large.
FIG. 9 is an explanatory diagram of the shape of a flame formed in a primary flame hole when the thermocouple mounting position and capacity of a conventional example are low.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Burner, 3 ... Flame hole plate, 7 ... Primary flame hole, 7a ... Outer edge part, 14 ... Thermocouple, 14a ... Heat sensitive part, 16 ... Step part, 16a ... Upper surface, 16b ... Side surface

Claims (1)

A burner provided with a flame hole plate in which a series of flame holes in which a large number of slit flame holes are arranged linearly in the longitudinal direction, and a thermoelectric element heated by the flame of the burner,
In the incomplete combustion preventing device for detecting incomplete combustion of the burner based on the electromotive force obtained from the thermoelectric element,
The central portion of the flame hole plate in which the flame hole array is arranged is lifted to form a step portion along the longitudinal direction, and the slit flame hole is opened from the upper surface to the side surface of the step portion. An incomplete combustion preventing apparatus, wherein a flame formed in a flame hole is spread in a lateral direction, and a heat sensitive part of the thermoelectric element is provided at a position heated by a side surface of the flame spread in the lateral direction.

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