JP2006118758A - Gas cooker - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inexpensive small kitchen range capable of certainly detecting occurrence of incomplete combustion and discriminating the supplied gas type. <P>SOLUTION: The lower part of a combustion casing 3 of which top face is blocked by a glass top plate 2 is provided with a surface combustion type burner 4 made of a gas permeable porous body and employs the surface facing the glass top plate 2 as the radiation surface, and a radiation mat 5 that is made of a gas permeable porous body, passes flue gas of the burner 4, recovers exhaust heat, and employs the surface facing the glass top plate 2 as the radiation surface. A heated object mounted on the top face of the glass top plate 2 is heated. The radiation mat 5 is provided with a through hole section 6 preferably having a diameter equal to or longer than an antiphlogistic distance, an exhaust port 8 is provided with a flame detecting means 12, and a combustion controlling means 31 for stopping the combustion of the burner 4 when the flame detecting means 12 detects a flame. The flame detecting means 12 is a temperature detecting means. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a gas stove in a form in which an object to be heated is placed on the upper surface of a combustion soot and a flame is not exposed during heating.

  Conventionally, a combustion soot whose upper surface is closed with a glass top plate is disposed below the glass top plate, and a surface combustion type burner having an upper surface as a combustion surface is provided below the combustion soot. A gas stove that heats an object to be heated such as a pan placed on the upper surface is known (see, for example, Patent Document 1).

  In the gas stove, the burner is formed in an annular shape, and a radiation mat made of a porous material having air permeability is attached to the inner diameter portion of the burner, and the combustion exhaust gas in the combustion soot is exhausted through the radiation mat. In this way, exhaust heat is recovered. In this way, in addition to the combustion surface of the burner, the radiant mat is also red-hot, and the radiated heat from the combustion surface and the radiant mat and the heat of the combustion exhaust gas are used to heat the object through the glass top plate. Things can be heated with high thermal efficiency.

  By the way, in the gas stove, the gas type of the fuel gas to be supplied is set in advance such as city gas such as the gas group 13A or LPG or the like, so that the amount is suitable for the fuel gas of the set gas type. In addition, the supply amounts of the fuel gas and the combustion air are adjusted. The gas types are classified by, for example, the Wobbe index, and LPG has a higher Wobbe index than city gas such as the gas group 13A.

  The Wobbe index is a value obtained by dividing the amount of heat of gas by the square root of the specific gravity of the gas with respect to the air. The higher the Wobbe index, the greater the amount of combustion air supplied to the fuel gas. Therefore, for example, in a gas stove adjusted for LPG, the supply amount of combustion air per unit volume of fuel gas is increased compared to city gas such as the gas group 13A having a lower Wobbe index. Yes. In such a gas stove, even if city gas such as the gas group 13A having a lower Wobbe index than the set gas type is erroneously supplied, the supply amount of the combustion air becomes excessively large for the city gas and ignites. There is nothing.

  On the other hand, in the gas stove adjusted for city gas such as the gas group 13A, the supply amount of the combustion air per unit volume of the fuel gas is reduced as compared with the LPG having a higher Wobbe index. . Therefore, if LPG having a Wobbe index higher than the set gas type is erroneously supplied to such a gas stove, although it ignites, the supply amount of combustion air may be insufficient and incomplete combustion may occur. There is a problem.

  In order to solve the above problem, a CO sensor is provided in the exhaust passage of the gas stove, and it is determined that incomplete combustion has occurred when the CO sensor detects CO of a predetermined reference value or more, It is conceivable to stop the combustion of the gas burner.

  However, the CO sensor not only greatly increases the cost, but also has a disadvantage of low reliability because it is poisoned by tempura oil or the like entering from the exhaust port through which the exhaust passage communicates.

  In order to solve the problem, a temperature sensor is provided on the combustion surface of the burner or the exhaust passage so that the combustion of the gas burner is stopped when an abnormal combustion state due to a difference in gas type is detected by the temperature sensor. Can be considered.

However, gas stoves that are adjusted for city gas such as the gas group 13A can only increase up to about 20% of the preset gas supply amount even if the LPG is supplied and the gas supply amount increases. Since no more LPG is discharged as unburned gas, there is no great difference in the surface temperature of the combustion surface, the degree of red heat, the temperature of the combustion exhaust gas, etc. between the city gas and LPG, and the abnormal combustion state There is a disadvantage that it is difficult to detect.
JP 2002-206713 A

  The present invention can eliminate such inconvenience and reliably detect the occurrence of incomplete combustion when fuel gas of a gas type different from a preset gas type is supplied and incomplete combustion occurs. Another object is to provide an inexpensive gas stove that can determine the type of gas being supplied.

  In order to achieve the above object, the gas stove of the present invention has a combustion soot whose upper surface is closed by the glass top plate below the glass top plate, and a breathable porous body below the combustion soot. A surface combustion burner comprising a surface facing the glass top plate as a combustion surface, and a waste gas from the combustion exhaust gas of the burner made of a breathable porous body to recover exhaust heat. In a gas stove that is provided with a radiation mat having a radiation surface as a radiation surface and heats an object to be heated placed on the upper surface of the glass top plate, the radiation mat is provided with a through-hole portion, and the radiation mat Flame detection means is provided in the vicinity of an exhaust port for discharging combustion exhaust gas that has passed through the mat, and combustion control means for stopping combustion of the burner when the flame detection means detects flame is provided.

  When the gas stove of the present invention is adjusted for city gas such as the gas group 13A, when a fuel gas having a higher Wobbe index than the city gas such as LPG is supplied, a part of the gas stove burns as unburned gas. It is discharged together with the exhaust gas. The exhaust gas containing the unburned gas is exhausted by being passed through the radiation mat. However, in the gas stove according to the present invention, the through hole is provided in the radiation mat. A part of the heat is exhausted through the through-hole without being recovered.

  As a result, the combustion exhaust gas containing the unburned gas is hot, and when it reaches the exhaust port and comes into contact with the atmosphere used as the secondary air for combustion, it ignites and produces a flame. Therefore, in the gas stove according to the present invention, flame detection means is provided in the vicinity of the exhaust port, and when the flame detection means detects the flame, the combustion control means causes incomplete combustion due to incorrect fuel gas supply. Is determined, and combustion of the burner is stopped.

  Therefore, according to the gas stove of the present invention, it is possible to reliably prevent the occurrence of incomplete combustion by inexpensive means and to determine the type of gas supplied to the gas stove.

  In the gas stove of the present invention, it is preferable that the through hole has a diameter equal to or greater than a flame extinguishing distance. When the through-hole has a diameter equal to or greater than the flame extinguishing distance, the combustion exhaust gas containing the unburned gas can maintain a temperature at which it can be reliably ignited at the exhaust port.

  In the gas stove of the present invention, a temperature sensor, a thermistor, a frame rod, or the like can be used as the flame detection means. However, since a flame can be detected reliably at a low cost, it is preferably a thermocouple type temperature sensor. .

  Next, embodiments of the present invention will be described in more detail with reference to the accompanying drawings. FIG. 1 is a perspective view showing the configuration of the gas stove according to the present embodiment, and FIG. 2 is a system configuration diagram showing the configuration of the gas stove shown in FIG.

  As shown in FIGS. 1 and 2, in the gas stove 1 of the present embodiment, a combustion rod 3 whose upper surface is closed by the glass top plate 2 is disposed below the glass top plate 2 made of heat-resistant glass such as ceramic glass. And a surface combustion burner 4 having a surface facing the glass top plate 2 as a combustion surface and a radiation mat 5 having a surface facing the glass top plate 2 as a radiation surface. ing. The burner 4 and the radiation mat 5 are both made of an air-permeable porous body, and the radiation mat 5 is provided at the inner diameter portion of the annular burner 4, and the radiation mat 5 has a fuel gas at the center thereof. A through hole 6 having a diameter equal to or greater than the flame extinguishing distance is formed.

  The gas stove 1 heats an object to be heated such as a pan placed on the glass top plate 2 with a burner 4 and a radiation mat 5, supplies combustion air to the burner 4, and A supply / exhaust fan 9 for sending combustion exhaust gas from the exhaust passage 7 to the exhaust port 8 via the radiation mat 5 and the through hole 6, a heating start / stop switch 10 for instructing start / stop of the heating operation, and a heating amount A heating amount setting switch 11 to be set and a thermocouple type which is provided at a downstream position facing the exhaust port 8 of the exhaust passage 7 and detects the generation of a secondary flame at the exhaust port 8 by detecting the temperature of the combustion exhaust gas. And a temperature sensor 12.

  Combustion air is supplied to the burner 4 through an air supply passage 20 by an air supply / exhaust fan 9, and fuel gas is jetted into the air supply passage 20 from a nozzle 22 provided at the tip of a gas supply pipe 21. The gas supply pipe 21 is provided with a gas source valve 23 and a gas on-off valve 24 in order from the upstream side. The gas stove 1 is adjusted for the city gas of the gas group 13A, and the supply / exhaust fan 9 is adjusted to the supply amount when the city gas is supplied from the gas source valve 23 and the gas on-off valve 24. An appropriate amount of combustion air is supplied.

  Further, the gas stove 1 includes a controller 30 constituted by a microcomputer or the like, and its operation is controlled by the controller 30. The controller 30 receives output signals from the heating start / stop switch 10 and the heating amount setting switch 11 for setting the heating amount, and detects the operation state of each switch based on these output signals. In addition, the controller 30 outputs control signals to the supply / exhaust fan 9, the gas source valve 23, and the gas on / off valve 24, and the supply / exhaust fan 9 is operated according to the operation of the heating start / stop switch 10 and the heating amount setting switch 11. And the operation of the gas source valve 23 and the gas on-off valve 24 are controlled.

  Further, the combustion control means 31 provided in the controller 30 determines that a secondary flame has occurred at the exhaust port 8 when the temperature of the combustion exhaust gas detected by the temperature sensor 12 exceeds a predetermined temperature, Burning of the burner 4 is stopped.

  Next, the operation of the gas stove 1 of this embodiment will be described.

  When the gas stove 1 is turned on, the controller 30 waits for the heating start / stop switch 10 to be turned on. When the user turns on the heating start / stop switch 10, the burner 4 is ignited. The ignition process of the burner 4 is performed by operating the air supply / exhaust fan 9 to supply combustion air to the air supply passage 20 and causing a spark discharge to occur in an ignition plug (not shown). Is opened and fuel gas supply is started. When the burner 4 is normally ignited, the controller 30 adjusts the opening degree of the gas on-off valve 24 so that the heating amount set by the heating amount setting switch 11 is reached, and the burner 4 and the radiation mat 5 are adjusted. Control the amount of heating.

  In the gas stove 1, the fuel gas is mixed with the combustion air in the air supply passage 20 to form an air-fuel mixture. When the burner 4 is ignited by the ignition process, the air-fuel mixture is formed on the combustion surface of the burner 4. Burns and high-temperature combustion exhaust gas is generated in the combustion soot 3. The combustion exhaust gas passes through the radiation mat 5 made of the air-permeable porous body and is exhausted to the exhaust passage 7. At this time, exhaust heat is recovered by the radiation mat 5, and the radiation mat 5 is red hot. Releases radiant heat. As a result, the glass top plate 2 is heated with high thermal efficiency by the radiant heat from the burner 4 and the radiant mat 5 and the heat of the combustion exhaust gas. On the other hand, since the radiation mat 5 is provided with the through hole 6, a part of the combustion exhaust gas is directly discharged to the exhaust passage 7 through the through hole 6 without collecting exhaust heat by the radiation mat 5. .

  By the way, the gas stove 1 is adjusted for the city gas of the gas group 13A as described above, and when the city gas is supplied, the temperature of the combustion exhaust gas discharged from the exhaust port 8 through the exhaust passage 7 is adjusted. Is about 400 ° C. Further, when the city gas is supplied to the gas stove 1, since an appropriate amount of combustion air is supplied, the city gas is completely burned by the burner 4, and the combustion exhaust gas contains almost carbon monoxide. It does not contain unburned gas. Therefore, the combustion exhaust gas is discharged from the exhaust port 8 as it is.

  On the other hand, when LPG is erroneously supplied to the gas stove 1, the LPG has a higher Wobbe index than the city gas, so that the gas supply amount to the burner 4 is increased by about 50% compared to the case of the city gas. In this case, the combustion amount of the gas stove 1 can only cope with an increase of about 20% relative to the preset supply amount of the combustion air for the city gas. Therefore, about 30% of the increased gas supply amount of 50% is incompletely combusted or discharged into the exhaust passage 7 together with the combustion exhaust gas as unburned gas.

  At this time, since the radiation mat 5 includes the through holes 6 as described above, a part of the combustion exhaust gas is directly exhausted through the through holes 6 without exhaust heat being collected by the radiation mat 5. It is discharged into the passage 7. When the exhaust gas reaches the exhaust port 8 and comes into contact with the atmosphere, the combustion exhaust gas is hot enough to pass through the through-hole 6 and the exhaust heat is not recovered by the radiation mat 5, so that it is not contained in the combustion exhaust gas. The combustion gas ignites using the atmosphere as the secondary air for combustion, and forms a secondary flame in the vicinity of the downstream side of the exhaust port 8.

  When the secondary flame is formed, the temperature of the combustion exhaust gas rises in the vicinity of the exhaust port 8 and reaches about 800 ° C. Therefore, in the gas stove 1, when the temperature sensor 12 detects an increase in the temperature of the combustion exhaust gas due to the formation of the secondary flame, the combustion control means 31 determines that incomplete combustion has occurred due to an incorrect gas type being supplied. Immediately stop the combustion of the burner 4.

  The combustion stop of the burner 4 is the same as a normal combustion stop by turning off the heating start / stop switch 10, and the controller 30 closes the gas source valve 23 and the on-off valve 24 to shut off the supply of fuel gas. Then, the air supply / exhaust fan 9 is operated at a predetermined rotational speed to perform the post purge process. By the post-purge process, the combustion exhaust gas and unburned gas staying in the combustion soot 3 are discharged.

  In the above-described embodiment, the temperature sensor 12 is disposed at the downstream position facing the exhaust port 8 so as to directly detect the flame temperature. However, the generated flame is disposed near the upstream side of the exhaust port 8. The occurrence of a flame may be determined by detecting a temperature rise based on the radiant heat or heat transfer through a wall constituting the exhaust passage 7.

The perspective view which shows the structure of the gas stove which concerns on this invention. The system block diagram which shows the structure of the gas stove shown in FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Gas stove, 2 ... Glass top plate, 3 ... Combustion soot, 4 ... Surface combustion type burner, 5 ... Radiant, 6 ... Through-hole, 8 ... Through-hole, 12 ... Temperature detection means (flame detection means), 31 ... Combustion control means.

Claims (3)

A combustion soot whose upper surface is closed by the glass top plate is disposed below the glass top plate, and a surface made of a breathable porous body and facing the glass top plate is a combustion surface at the bottom of the combustion soot. A surface-burning burner, and a radiating mat that is made of a breathable porous body and that recovers exhaust heat by passing the combustion exhaust gas of the burner and that has a surface facing the glass top plate as a radiation surface. In the gas stove configured to heat the heated object placed on the upper surface of the glass top plate,
A through hole is provided in the radiation mat, flame detection means is provided in the vicinity of an exhaust port for discharging combustion exhaust gas that has passed through the radiation mat, and combustion of the burner is stopped when the flame detection means detects flame. A gas stove comprising a combustion control means.   The gas stove according to claim 1, wherein the through hole has a diameter equal to or greater than a flame extinguishing distance.   The gas stove according to claim 1 or 2, wherein the flame detection means is a temperature detection means.

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