JP2002333131A - Gas combustion apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve stability of detection operation for carbon monoxide concentration with a CO sensor (60), and prevent acidic liquid particles produced upon initial combustion of gas burners (36), (37) from adhering to the CO sensor (60) in a gas combustion apparatus having the CO sensor (60) for detecting the carbon monoxide concentration provided on an exhaust passage permitting combustion exhaust air from the gas burners (36), (37) to flow through. SOLUTION: The foregoing CO sensor (60) is accommodated in an exhaust storage box (62), an opened one end section of which is connected with a connection hole opened in a constitution wall of the exhaust storage box (62), and along a peripheral side wall of which a vent pipe (63), which vent holes (67). (67) exposed in a flow of the combustion exhaust air penetrate, is provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas combustion apparatus, and more particularly to a gas combustion apparatus having improved stability in detecting the incomplete combustion of a gas burner. Applicable to equipment.

[0002]

2. Description of the Related Art A water heater having a function of forcibly stopping an operation when a gas burner enters an incomplete combustion state has a structure disclosed in Japanese Patent Application Laid-Open No. Hei 9-217929. In this case, as shown in FIG. 6, the lower end of a casing (10) in which first and second gas burners (11) and (12) for selectively burning in order to switch the hot water supply capacity are provided at the lower end thereof. 13) is connected and the first and second
Above the gas burners (11) and (12), a number of heat absorbing fins (14) (1
4) and a heat exchange section (16) comprising a water pipe (15) penetrating therethrough.

On the other hand, as shown in FIGS. 6 and 7, an exhaust port (18) having an opening width substantially equal to the lateral width of the casing (10) is formed in the upper front surface of the casing (10). The exhaust port (18) and the heat exchange section (16) in the casing (10) communicate with each other via a passage restricting section (17). Then, the passage expanding portion (2) connected from the passage throttle portion (17) to the exhaust port (18).
The constituent wall of (0) is provided with a CO sensor (19) for detecting the concentration of carbon monoxide in the combustion exhaust gas.

Next, the operation of the water heater will be described. When only the second gas burner (12) is burned (small capacity state) by the air supply from the air supply fan (13), the first gas burner is activated.
The air from the air supply fan (13) ascending in the outer peripheral area of (11) and the combustion exhaust gas of the second gas burner (12) are caused to flow downstream by a group of heat absorbing fins (14) and (14) arranged at an angle. Side so as to collide with each other, whereby the combustion exhaust gas diluted with the air passes from the passage throttle portion (17) to the CO sensor (19) through the arrangement portion of the CO sensor (19) to the outside through the exhaust port (18). Discharged.

When the concentration of carbon monoxide in the combustion exhaust gas detected by the CO sensor (19) exceeds a predetermined reference value, the control device (21) judges this state, and the first and second states are determined.
The gas source valve (23) provided in the gas circuit (22) of the gas burners (11) and (12) is closed to forcibly stop combustion, thereby ensuring a safe state.

In this case, even if only one of the second gas burners (12) is burned as described above, the first gas burner in a fire-extinguishing state with the combustion exhaust gas from the second gas burner (12).
Air rising in the outer peripheral area of (11) is mixed in the heat absorbing fins (14) (14) group and the passage narrowing portion (17) arranged in a C shape. Therefore, the enlarged path portion (2) where the CO sensor (19) is disposed
In (0), the variation in the concentration of the combustion exhaust gas depending on the location is reduced, and as a result, the first and second gas burners (11) (1)
2) It is possible to detect the carbon monoxide concentration of the combustion exhaust gas generated from the whole with high accuracy.

[0007]

However, in the above conventional apparatus, the stability of the operation of detecting the concentration of carbon monoxide by the CO sensor (19) cannot be ensured, and the first and second gas burners (11) and (12) cannot be ensured. There is a problem that mist-like liquid particles having a high acidity, which are often generated in the early stage of combustion, adhere to the CO sensor (19) and easily corrode them.

[0008] This is because the CO sensor (19) is exposed to the flow of the combustion exhaust gas. That is, in the above-described conventional apparatus, the CO sensor (19) is disposed in such a manner that the CO sensor (19) is exposed in the enlarged passage (20) near the exhaust port (18) of the combustion exhaust passage. ) Is exposed to the combustion exhaust stream. Therefore, if the flow rate of the combustion exhaust gas flowing through the CO sensor (19) is suddenly changed due to a change in the rotation speed of the air supply fan (13) due to a change in the amount of combustion of the first and second gas burners (11) and (12), The degree to which the CO sensor (19) is cooled by the rapidly changing combustion exhaust gas greatly changes, whereby the temperature of the CO sensor (19) changes and its electrical characteristics change. This makes the operation of detecting the concentration of carbon monoxide by the CO sensor (19) unstable.

In the early stage of combustion of each gas burner,
The temperature of the heat exchange section (16) etc. is not sufficiently raised, and the combustion exhaust gas in contact with it is cooled below the dew point. appear. Then, when the combustion exhaust containing the large amount of liquid particles contacts the CO sensor (19) exposed in the combustion exhaust stream,
The liquid particles in the combustion exhaust gas adhere to the CO sensor, and the CO sensor (19) is easily corroded by acidic components contained therein.

[0010] The present invention has been made in view of the above-mentioned point, and has been made in view of the fact that "in an exhaust passage through which combustion exhaust gas from a gas burner flows,
In a gas combustion device provided with a CO sensor for detecting the concentration of carbon monoxide, the stability of the operation of detecting the concentration of carbon monoxide by the CO sensor is improved, and the gas is generated in the early stage of combustion of the gas burner. An object is to prevent acidic liquid particles from adhering to a CO sensor.

[0011]

Means for Solving the Problems [1] The technical means of the present invention for solving the above-mentioned problem is as follows: "The CO sensor is housed in an exhaust gas storage box, and the constituent wall of the exhaust gas storage box is And a ventilation pipe is provided on the peripheral side wall, the ventilation hole being exposed in the flow of the combustion exhaust gas, and the inside of the ventilation pipe and the inside of the exhaust gas storage box communicate with each other. It is.

According to the above technical means, the combustion exhaust gas that has entered the ventilation pipe from the ventilation hole gradually diffuses into the ventilation pipe and into the exhaust storage box connected to one end opening of the ventilation pipe. As a result, the combustion exhaust gas stays in the exhaust gas storage box in a substantially stagnant state, and the CO sensor is exposed to the combustion exhaust gas in the staying state. Therefore, the CO
The sensor detects the carbon monoxide concentration of the combustion exhaust gas in the substantially stagnant state.

[2] The method according to the above [1], wherein a leak hole for leaking the combustion exhaust gas stored in the exhaust gas storage box into the exhaust passage is formed in a wall of the exhaust gas storage box. In this case, the combustion exhaust gas in the exhaust gas storage box is leaked from the leak hole, and the ventilation in the exhaust gas storage box is promoted within an appropriate range.

[3] In the item [1] or [2] above, wherein the plurality of ventilation holes are formed at intervals in the axial direction of the ventilation pipe, Are formed so as to be scattered at intervals in the axial direction. Therefore, even when the combustion exhaust gas flows in a laminar state,
Combustion exhaust gas flowing through different portions in the thickness direction of the layer is sampled at the plurality of ventilation holes, and diffused into the ventilation pipe and into the exhaust storage box. Thereby, the detection accuracy of the carbon monoxide concentration by the CO sensor is improved.

[4] In the above item [1] to [3], wherein the assembly of the ventilation pipe and the exhaust storage box is located downstream of a passage restricting portion formed by narrowing a passage cross section of the exhaust passage. In that, the combustion exhaust gas having different carbon monoxide concentrations generated from different gas burners among the plurality of gas burners arranged is turbulently generated by a change in flow velocity when passing through the passage restricting portion. The combustion exhaust gases having different carbon monoxide concentrations are mixed to make the concentrations uniform.

[0016]

According to the present invention having the above configuration, the following specific effects are obtained. Since the CO sensor detects the concentration of carbon monoxide in the exhaust gas in the exhaust storage box in a substantially stagnant state, the flow of the combustion exhaust gas is blown to the CO sensor and cooled as in the conventional device described above. There is no performance change. Therefore, there is no inconvenience that the detection operation of the CO sensor becomes unstable even if the flow velocity of the combustion exhaust changes rapidly. Also, since the CO sensor is not exposed to the combustion exhaust stream, the combustion exhaust containing a large amount of liquid particles generated in the early stage of combustion of the gas burner is blown to the CO sensor, and the liquid particles do not adhere to the CO sensor. There is no fear that the CO sensor is corroded by the acidic components contained in the combustion exhaust gas.

According to the second aspect, the combustion exhaust gas that has not passed for a very long time since the generation is easily stored in the exhaust storage box. Therefore, by appropriately setting the size of the leak hole, it is possible to appropriately set the responsiveness of the detection operation while ensuring the stability of the operation of detecting the concentration of carbon monoxide.

According to the third aspect, since a plurality of ventilation holes are formed scattered in the axial direction of the ventilation pipe, the accuracy of detecting the concentration of carbon monoxide in the combustion exhaust gas flowing in a laminar state is improved as described above. I do.

According to the fourth aspect, the mixing of the combustion exhaust gas is promoted by the passage restricting portion formed by narrowing the passage cross section of the exhaust passage, so that the accuracy of detecting the concentration of carbon monoxide by the CO sensor is further improved.

[0020]

Next, an embodiment of the present invention will be described. FIG. 1 is a longitudinal sectional view of a water heater showing an example of the gas combustion apparatus of the present invention, and FIG. 2 is a II-II of FIG.
It is a side view of the water heater which cut | disconnected the line part.

The water heater includes a burner case (31) containing a gas burner and a heat exchanger (41) connected to the upper end thereof.
And an exhaust collecting cylinder (51) continuously provided thereabove, and these parts have the following specific structures.

[About Burner Case (31)] An air supply port is provided on the bottom wall of the burner case (31) formed in a rectangular box shape which is open upward.
(32) is formed, and the outlet of the air supply fan (33) is connected to the air supply port (32). In addition, the air supply port (3
The upper space of 2) is vertically divided by an air supply distribution plate (35) in which a number of through holes (34) (34) are formed. A small burner (36) and a large burner (37) are arranged above the air supply distribution plate (35), and the small burner (36) is provided when the water heater operates in a small capacity state. Only the large burner (37) burns when operating in the medium capacity state, and the small burner (36) and the large burner (37) burn together when operating in the high capacity state. It has become.

[About the heat exchanger (41)] The above burner case
The heat exchanger (41) connected to the upper end of the (31) includes a can (42) and a water pipe (43), and the heat exchanger (41) passes through the vicinity of the upper end of the can (42) in a meandering state. Water pipe (43) has many heat absorbing fins (44) (44)
Groups are connected in series.

[Exhaust Collecting Tube (51)] The heat exchanger (4)
The exhaust collecting cylinder (51) connected to the upper end of (1) has a duct part (52) formed in a rectangular box shape with an open lower end, and an exhaust guide plate arranged in such a manner that the inside thereof is vertically divided. (55) and duct
(52) a cylinder (54) connected to the ceiling hole (53); and a sensor box (61) disposed below the ceiling hole (53). A bracketed CO sensor (60) for detecting the carbon monoxide concentration of the combustion exhaust gas is accommodated in the parentheses.

* Exhaust guide plate (55) The exhaust guide plate (55) has a rectangular top plate (56) which vertically divides the duct portion (52) and has a bent lower part (57) formed on the outer periphery. The bent hanging part (57) is fixed to the peripheral side plate (50) of the duct part (52) with screws (58) (58). As shown in FIG. 3, an exhaust guide port (59) as a passage restricting portion is opened in the rectangular top plate (56) of the exhaust guide plate (55) near one end in the longitudinal direction thereof. Thus, a large distance is secured between the exhaust guide port (59) and the sensor box (61).

* Sensor box (61) As shown in FIGS. 3 to 5, the sensor box (61)
Is composed of an exhaust storage box (62) containing a CO sensor (60) and a ventilation pipe (63) protruding from one end of the exhaust storage box (62), and a CO sensor (60) is arranged in the exhaust storage box (62). A cover plate (64) located closer to the ventilation pipe (63) than the installation portion is provided. Then, as shown in FIG. 5, the lateral width of the cover plate (64) is set shorter than that of the exhaust storage box (62), whereby both side edges of the cover plate (64) and the exhaust storage box (62) Side walls (73) (7
The arrangement portion of the CO sensor (60) and the side of the ventilation pipe (63) communicate with each other through the gap portions (65) and (65) with the third component (3). In addition, cover plate (64)
Are formed in a rectangular cross-section that is curved so that the vertical interval increases as approaching the tip of the CO sensor (60) from the ventilation pipe (63) side. Therefore, even if the drain (66) is generated and adheres to the inner surface of the upper inclined plate (640) extending obliquely upward from the center of the tip of the cover plate (64), this is transmitted down the upper inclined plate (640) and obliquely downward. The fluid (66) flows through the CO sensor
(60) The inconvenience of dripping on the top can be prevented. Exhaust storage box
A leak hole (71) is formed in the front wall (70) located on the side of the ventilation pipe (63) in (62).

On the other hand, a vent hole (63) is formed in a side wall of a side facing a flow of combustion exhaust gas (discussed below) discharged from an exhaust guide port (59) formed in the exhaust guide plate (55). While 67 and 67 are formed, ventilation holes 67 and 67 are also formed in the bottom wall of the ventilation pipe 63. And these vents (6
7) (67) are arranged at a predetermined pitch at intervals in the axial direction of the ventilation pipe (63). Therefore, even if the combustion exhaust gas flows in a laminar flow state, the combustion exhaust gas flowing through different portions in the thickness direction of the layer is taken into the ventilation pipe (63) from the plurality of ventilation holes (67) (67).

As shown in FIG. 4, the CO sensor (60) is composed of an electronic element group (69) including a gas detection element and an electric resistance element housed in a protective cap (68). The arrangement of the electronic element group (69) and the inside of the exhaust gas storage box (62) communicate with each other through windows (49) and (49) formed in the cap (68).

[Actual Operation] Next, the actual operation of the water heater will be described. When the hot water supply operation is started in the small capacity state, an ignition device (not shown) is activated, and only the small burner (36) starts burning.

On the other hand, the air discharged from the air supply fan (33) is diffused through the through holes (34) and (34) so as to jet uniformly from the entire surface of the air supply distribution plate (35). The small burner (36) is supplied as combustion air. Further, the jet air from the air supply distribution plate (35) passes around the large burner (37) in the fire-extinguishing state and is supplied to the downstream side. Therefore, the combustion exhaust gas generated in the small burner (36) and the air passing through the large burner (37) are mixed with each other in a laminar flow state without being mixed with each other.
It flows through the portion and merges at the exhaust guide port (59) of the exhaust guide plate (55). Then, the flow rates of the air and the combustion exhaust gas rapidly increase when passing through the exhaust guide port (59) having a small opening area, and are reduced again in the downstream duct portion (52). Then, the combustion exhaust and the air are mixed by the speed change to generate combustion exhaust having a reduced concentration, and the combustion exhaust reaches the arrangement portion of the sensor box (61).

The combustion exhaust gas that has reached the sensor box (61) is discharged to the outside from an exhaust cylinder (54) positioned above the sensor box (61), while the combustion exhaust gas is formed in a ventilation pipe (63). Diffusion from the ventilation holes (67) and (67) into the ventilation pipe (63) and diffusion of the combustion exhaust further expands into the exhaust storage box (62). As a result, the combustion exhaust gas remains in the exhaust gas storage box (62) in an almost stagnant state, and the CO sensor (60) detects the concentration of carbon monoxide in this atmosphere. Accordingly, the flow of the combustion exhaust is not blown to the CO sensor (60), and the CO sensor (60) is cooled, and the detection operation does not become unstable.

Accordingly, the rotation speed of the air supply fan (33) changes with the change in the amount of combustion of the small burner (36) and the large burner (37), thereby changing the flow velocity of the combustion exhaust flowing through the exhaust passage. However, the CO sensor (60) provided in the exhaust gas storage box (62) is not cooled by the flow of the combustion exhaust gas. This avoids the inconvenience that the resistance value of the electronic element group (69) constituting the CO sensor (60) changes and the detection operation becomes unstable. In addition, C in the stagnant combustion exhaust gas in the sensor box (61)
Since the O sensor (60) is located, the CO sensor (60) is not exposed to the combustion exhaust stream unlike the conventional one described above.
Therefore, the combustion exhaust gas containing a large amount of liquid particles generated by the large and small burners (37) and (36) in the initial stage of combustion is blown to the CO sensor (60), and the liquid particles do not adhere to the CO sensor (60). CO sensor based on acidic components contained in the combustion exhaust gas
Corrosion of (60) is suppressed.

When the carbon monoxide concentration of the combustion exhaust gas detected by the CO sensor (60) exceeds a predetermined reference value, a control device (not shown) judges this condition and determines whether the small burner (36) and The gas supply to the large burner (37) is shut off and the air supply fan (33) is stopped, thereby ensuring a safe state.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a water heater according to an embodiment of the present invention.

FIG. 2 is a side view of the water heater, taken along a line II-II in FIG.

FIG. 3 is a perspective view showing an arrangement relationship between an exhaust guide plate (55) and a sensor box (61).

FIG. 4 is a longitudinal sectional view of a sensor box (61).

FIG. 5 is a sectional view taken along a line VV in FIG. 4;

FIG. 6 is an explanatory view of a conventional example.

FIG. 7 is an explanatory view of a conventional example.

[Explanation of symbols]

 (36) ・ ・ ・ First gas burner (37) ・ ・ ・ Second gas burner (60) ・ ・ ・ CO sensor (62) ・ ・ ・ Exhaust storage box (63) ・ ・ ・ Ventilation pipe (71) ・ ・ ・ Leak Hole

Claims (4)

[Claims] In a gas combustion device provided with a CO sensor for detecting a concentration of carbon monoxide in an exhaust passage through which combustion exhaust gas from a gas burner flows, the CO sensor is housed in an exhaust storage box. A ventilation pipe protruding from a component wall of the exhaust gas storage box and having a peripheral hole penetrating a ventilation hole exposed in the flow of the combustion exhaust gas, provided in the ventilation pipe and the exhaust gas storage box; The inside is a gas combustion device that communicates with each other. 2. The gas combustion apparatus according to claim 1, wherein a leak hole through which a combustion exhaust gas stored in the exhaust gas storage box leaks into the exhaust passage is formed in a wall of the exhaust gas storage box. A gas combustion device in which is formed. 3. The gas combustion apparatus according to claim 1, wherein a plurality of the ventilation holes are formed at intervals in an axial direction of the ventilation pipe. 4. The gas combustion device according to claim 1, wherein the aggregate of the ventilation pipe and the exhaust storage box is formed by narrowing a cross section of the exhaust passage. The gas combustion device is located downstream of the gas combustion device.