JP4885172B2 - Gas stove - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve a problem that it takes a long time to detect an ember state in a routine to detect a misfire state since, in a conventional stove burner, the ember state that the flame of the burner is not extinguished though a fire extinguishing operation is performed is not independently detected though the misfire state that the flame of the burner is extinguished on the way is detected on the basis of a value of thermoelectric power from thermocouple disposed near the burner. <P>SOLUTION: This stove burner is constituted to independently detect the ember state separately from the detection of the misfire state. Concretely, a first threshold is determined, so that the occurrence of the misfire state is determined when the value of the thermoelectric power is lower than the first threshold, and furthermore, a second threshold higher than the first threshold is determined, so that the occurrence of the ember state is determined when the thermoelectric power is higher than the second threshold at a point when a prescribed monitoring time has been continued from a point when the fire extinguishing operation is performed. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a gas stove that includes a thermocouple in the vicinity of a gas burner and detects a misfire state or an afterfire state based on the state of a thermoelectromotive force output from the thermocouple.

  Conventionally, a gas stove provided with a thermocouple so as to be heated by the flame of the gas burner in the vicinity of the gas burner is known. While the gas burner is ignited, the thermocouple is heated by the flame and outputs a thermoelectromotive force.However, when the gas burner flame disappears, the thermoelectromotive force decreases, and the presence or absence of the gas burner flame is determined. Gas stoves that detect from the state of electromotive force are widely known.

  An example of such a gas stove is a gas stove that uses a single gas cock to increase / decrease the thermal power and open / close the gas supply path to the gas burner, without providing a cock switch that detects that the fire has been extinguished. There is known a gas stove that detects that a gas burner has extinguished only from a reduced power state and closes an electromagnetic safety valve (see, for example, Patent Document 1). In this case, the thermoelectromotive force is constantly monitored, the thermocouple continues to decrease for a predetermined time, for example, 5 seconds, and decreases after 5 seconds to a level of, for example, 0.62 times the thermoelectromotive force at the start of the decrease. It is judged that the gas burner has been extinguished when the two conditions are met simultaneously.

In this case, the cause of fire extinguishing is specified based on the rate of decrease in thermoelectromotive force, etc. For example, when extinguishing due to spillage from a pan or the like, the rate of decrease in thermoelectromotive force is fast. Thus, the occurrence of such a misfire condition is identified.
Japanese Patent Laid-Open No. 2002-130666 (paragraph 0008, FIG. 4) JP-A-2004-108694 (paragraph 0037)

  In the thing of the said patent document 1, while operating a gas cock manually and adjusting a thermal power, the fire extinguishing of a gas burner is performed. Therefore, when the fire power is reduced to reduce the heat and the cock is further turned to extinguish the gas burner, there is no afterfire condition in which the gas burner remains ignited even though the user performs the fire extinguishing operation. .

  On the other hand, in the thing of patent document 2, since a gas cock is rotated with a motor, supply of the gas to a gas burner cannot be stopped even if fire extinguishing operation was performed by the cause of failure etc., There is a risk of an afterfire condition in which the gas burner remains burned.

  However, since the device described in Patent Document 2 does not have a means for detecting that an afterfire condition has occurred, after the fire extinguishing operation is performed, the afterfire condition is detected unless a considerable time has elapsed. The trouble that cannot be done occurs.

  Then, this invention makes it a subject to provide the gas stove which can each detect a misfire state and an afterfire state appropriately in view of said problem.

  In order to solve the above problems, a gas stove according to the present invention comprises a thermocouple heated by a flame of a gas burner in the vicinity of the gas burner, and a controller for detecting the presence or absence of a flame of the gas burner by a thermoelectromotive force output from the thermocouple. The controller supplies gas to the gas burner at least when a misfire condition occurs where the flame is misfired during the combustion of the gas burner and when an afterfire condition occurs where the flame remains despite being extinguished. In the gas stove that forcibly stops the controller, the controller sets a first threshold value, determines that a misfire condition has occurred when the value of the thermoelectromotive force falls below the first threshold value, The thermoelectromotive force is higher than the second threshold when a predetermined monitoring time has elapsed from the time when the second threshold higher than the threshold is set and the fire extinguishing operation is performed. Characterized by determining that remaining fire condition occurs in the case.

  Conventionally, since only a function for detecting a misfire state has been provided, there is a problem in that it takes a long time to detect if an afterfire state is detected by a function for detecting a misfire state. Therefore, in the present invention, the function of detecting the misfire state and the function of detecting the afterfire state are provided separately. That is, in order to detect a misfire state, a first threshold value is set, and it is determined that a misfire state has occurred when the value of the thermoelectromotive force falls below the first threshold value. On the other hand, after the predetermined monitoring time has elapsed from the time when the second threshold value higher than the first threshold value was set and the fire extinguishing operation was performed, an after-fire condition occurred when the thermoelectromotive force was higher than the second threshold value. It was decided to judge.

  The second threshold value may be set based on the thermoelectromotive force at the time when the fire extinguishing operation is performed.

  As is apparent from the above description, the present invention is provided with a function for detecting a misfire condition and a function for detecting an afterfire condition separately, so that it is ensured that the afterfire condition has occurred and for a short time. Can be detected.

  With reference to FIG. 1, 1 is an example of a gas stove according to the present invention. The gas stove 1 is provided with two large burners 11 and a middle burner 12 on the upper surface, and a gas burner for grilling (a pair of an upper fire burner and a lower fire burner) in a grill cabinet 13 that can be taken in and out from the front. Is provided. In addition to the power switch 10, dials 11 a, 12 a, and 13 a that perform point fire extinguishing and heating power adjustment of each burner are provided on the front surface. For example, when the middle burner 12 is ignited, the middle burner 12 is ignited by pressing the dial 12a to perform the ignition operation. Then, the heating power is adjusted by turning the dial 12a left and right, and the middle burner 12 is extinguished by pressing the dial 12a again.

  As shown in FIG. 2, each of the burners is connected to a large burner 11, an intermediate burner 12, and branch pipes 31 that branch the gas to both burners of the grill 13 through a main valve 3 that is an electromagnetic on-off valve. It is provided in parallel. Each branch pipe 31 is provided with a thermal power adjustment unit 2.

  The thermal power adjustment unit 2 includes a thermal power adjustment unit 4 that adjusts the opening degree by a motor driven by a signal from the controller 6, and an electromagnetic safety valve 5 provided in series upstream of the thermal power adjustment unit 4. ing. The electromagnetic safety valve 5 is opened by a heating power adjusting motor, but is kept open by the electric power supplied from the controller 6 during ignition of the gas burner.

  Each burner is provided with a thermocouple 15 that is a flame sensor for detecting ignition in an ignition state. The output signals from these thermocouples 15 are individually input to the controller 6.

  Each burner is provided with a spark plug 16 as an ignition means. The operation of each of these spark plugs 16 is controlled by the controller 6, but even when any one of the burners is ignited, all the spark plugs 16 are operated to generate a spark discharge with each burner. Has been.

  Among these gas burners, when a plurality of gas burners are used, the original valve remains open, and if any one of the gas burners being ignited is extinguished, The gas burner is extinguished by closing the electromagnetic safety valve 5 provided for the fire extinguishing operation.

  With reference to FIG. 3, a curve RH shows a reduced state of the thermoelectromotive force when the gas burner is extinguished in a strong fire state. A curve RL indicates a state in which the thermoelectromotive force is reduced when the gas burner is extinguished in a low fire state.

  In the present invention, detection of the misfire state and detection of the afterfire state are performed separately. If the gas burner is in an ignition state, only the misfire state is detected. Specifically, when the first threshold value V1 is set and the state where the thermoelectromotive force from the thermocouple 15 falls below this V1 continues for a predetermined time t1 or more, the thermoelectromotive force is generated in a state where the gas burner should be in an ignition state. It is determined that a misfire condition has occurred. Then, the controller 6 closes the electromagnetic safety valve 5 connected to the gas burner in which the misfire condition has occurred. In addition, while closing the electromagnetic safety valve 5, you may make it alert | report that the misfire state generate | occur | produced with an audio | voice, warning sound, light, etc. As described above, it was determined that the misfire state occurred when the state in which the thermoelectromotive force was lower than V1 continued for the predetermined time t1 or longer. However, the predetermined time t1 was set to be shorter or t1 was set to 0. Then, it may be determined that a misfire state has occurred immediately when the thermoelectromotive force falls below V1.

  Next, when a fire extinguishing operation is performed on the dial, it is monitored whether the thermoelectromotive force falls below V2, which is the second threshold, from when the fire extinguishing operation is performed until the monitoring time t2 elapses. Since the fire extinguishing operation has been performed, the thermoelectromotive force is lower than V2 in a normal state, but if the electromagnetic safety valve 5 cannot be closed due to some failure, the gas burner continues to burn. Therefore, the thermoelectromotive force does not fall below V2 even after the monitoring time t2 has elapsed. Then, the controller 6 determines that an afterfire condition has occurred, and closes the main valve 3. Then, the above-described notification is performed, and the operation of the gas stove 1 is prohibited until maintenance such as repair is completed. Note that whether or not the afterfire state has occurred is determined when the monitoring time t2 has elapsed, so even if the thermoelectromotive force is below V2 during the monitoring time, the time when the monitoring time t2 has elapsed If the thermoelectromotive force is not lower than V2, it is determined that an afterfire condition has occurred.

  Incidentally, in the embodiment shown in FIG. 3, the second threshold value V2 is fixed. However, as shown in FIG. 4, it may be determined based on the thermoelectromotive force at the time when the fire extinguishing operation is performed. . More specifically, for example, a value lower by a predetermined value V3 than the thermoelectromotive force at the time when the fire extinguishing operation is performed can be considered as the second threshold value.

  In addition, this invention is not limited to an above-described form, You may add a various change in the range which does not deviate from the summary of this invention.

The figure which shows the structure of one embodiment of this invention Block diagram showing piping status The graph which shows the reduction | decrease of a thermoelectromotive force, and the 1st threshold value and the 2nd threshold value Graph showing another example of the second threshold

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Gas cooker 2 Thermal power control unit 3 Main valve 4 Thermal power control part 5 Electromagnetic safety valve 6 Controller 10 Power switch 15 Thermocouple t1 Predetermined time t2 Monitoring time

Claims (2)

  A thermocouple heated by the flame of the gas burner is provided in the vicinity of the gas burner, and has a controller that detects the presence or absence of the flame of the gas burner by the thermoelectromotive force output from the thermocouple, and the controller is at least a flame during the combustion of the gas burner. In the gas stove that forcibly stops the supply of gas to the gas burner when a misfire condition that causes misfire occurs and when an after-fire condition where a flame remains despite the fact that the fire is extinguished, the controller A first threshold value is set, and it is determined that a misfire state has occurred when the value of the thermoelectromotive force falls below the first threshold value, and a second threshold value higher than the first threshold value is set, and the fire extinguishing operation is performed. It is determined that an after-fire condition has occurred when the thermoelectromotive force is higher than a second threshold at a time when a predetermined monitoring time has elapsed from the time of being performed. Sukonro.   The gas stove according to claim 1, wherein the second threshold value is set based on a thermoelectromotive force at the time when a fire extinguishing operation is performed.

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