JP5746674B2 - Cooker - Google Patents

Description

  The present invention relates to a cooking device. In particular, the present invention relates to a cooking device including a control unit that can appropriately determine incomplete combustion of an oven burner.

  2. Description of the Related Art Conventionally, there is known a heating cooker having a heating chamber for storing an object to be cooked, an oven burner for generating hot air disposed in a chamber separate from the heating chamber, and a circulation fan for circulating hot air into the heating chamber. (For example, Patent Document 1).

  In this type of heating cooker, it is necessary to take in external air with a circulation fan in order to generate gas by burning gas with an oven burner. The generated hot air is sent to the heating chamber, and during oven cooking, hot air containing a large amount of oily smoke circulates in the heating chamber, and part of the hot air becomes exhaust and is discharged from the heating chamber to the exhaust port. . As a result, an outlet and an inlet for circulating hot air provided on the constituent walls of the heating chamber, an exhaust outlet for exhausting exhaust from the heating chamber, and an exhaust outlet for exhausting exhaust to the outside, etc. May be clogged by oil or the like, and it is difficult for external air to be taken in, and incomplete combustion may occur in the oven burner.

  When the above incomplete combustion occurs, an overheat switch such as a bimetal is disposed at a position where the combustion flame is burned by the incomplete combustion state by utilizing the fact that the combustion flame extends due to insufficient oxygen. ing. According to this, when the overheat switch, which is a means for detecting incomplete combustion, is overheated by the combustion flame, it can be determined that a combustion failure has occurred and combustion of the oven burner can be stopped.

JP 2000-249343 A

  Although incomplete combustion can be determined when the above-mentioned overheat switch is provided, the incomplete combustion can be determined. However, if the combustion flame extends to some extent and the overhit switch is not overheated directly by the combustion flame, it will not be determined as incomplete combustion. It is difficult to determine combustion failure early and reliably.

  On the other hand, in order to change the combustion amount of the burner, a thermocouple is disposed near the flame hole of the burner, and the gas supply amount is controlled based on the thermoelectromotive force from the thermocouple burned by the combustion flame. ing. Therefore, since the shape of the combustion flame changes when incomplete combustion occurs, a change in the absolute value of the thermoelectromotive force during ignition of the oven burner is detected by using a thermocouple as a means of detecting incomplete combustion instead of the overhit switch. If so, it is considered that incomplete combustion can be determined.

  By the way, the gas supplied to a heating cooker such as a gas stove differs depending on the region, and a plurality of gas types having different components such as city gas, propane gas, and butane gas are used. Since these gas types have different calorific values, when determining incomplete combustion based on the absolute value of the thermoelectromotive force output from the thermocouple as described above, it is necessary to set a determination threshold for each gas type. There is. Therefore, in manufacturing a cooking device, it is necessary to design a control unit in which different threshold values are set according to the gas type of the supply gas, and to incorporate this into the cooking device.

  However, designing a different control unit for each gas type has a problem of lack of versatility and high cost. In consideration of safety, it may be possible to set a threshold value for the gas type with the highest calorific value, but in this case, incomplete combustion will occur if oven cooking is performed using another gas type with a low calorific value. However, only a thermoelectromotive force below the threshold value can be obtained, and it is determined that a combustion failure has occurred, and combustion of the oven burner is stopped.

  Further, in order to correspond to a plurality of gas types with a single control unit, a plurality of thresholds when incomplete combustion occurs in the control unit are set, for example, according to the type of gas type to be supplied It is also conceivable to change the threshold by, for example. However, it is complicated to change the setting every time the usage environment changes, and the setting change may be erroneous. Therefore, a cooking device that can determine incomplete combustion of the oven burner without changing the setting of the control unit by the user or installer is desired.

  The present invention has been made to solve the above problems, and the object of the present invention is to use a plurality of types of supply gases having different components in a heating cooker that circulates hot air generated by an oven burner. In the single control unit, the incomplete combustion of the oven burner is appropriately determined without changing the setting of the threshold value of the thermoelectromotive force.

The present invention comprises an oven burner that generates hot air by burning a supply gas;
A heating chamber for heating the cooking object;
A circulation fan that takes in external air that burns the oven burner and circulates hot air generated by the oven burner to the heating chamber;
A thermocouple facing the flame hole of the oven burner;
A control unit capable of determining incomplete combustion of the oven burner, and the control unit monitors the thermoelectromotive force output from the thermocouple when oven cooking is started,
During cooking, the maximum thermoelectromotive force is updated from the thermoelectromotive force during the oven burner ignition being monitored,
When the thermoelectromotive force during ignition of the oven burner being monitored is lower than a predetermined value with respect to the maximum thermoelectromotive force, the cooking device determines that the oven burner is in an incomplete combustion state.

In the heating cooker, since the external air is forcibly taken in by the circulation fan and the oven burner is burned, the suction inlet and outlet of the heating chamber, and further the exhaust outlet and exhaust outlet are partially blocked by oil. However, if most of these are not obstructed, the air around the oven burner and a certain amount of external air taken in can be burned together with the supply gas as combustion air, and the normal supply gas used A thermoelectromotive force equivalent to that in the combustion state can be generated. However, as the temperature of each part rises as the steady state is reached, the ventilation resistance increases and the amount of external air taken in decreases. If the hot air flow path such as the suction port or the outlet is closed to the extent that incomplete combustion is caused, but the combustion flame is not formed normally, the thermoelectromotive force gradually decreases. . On the other hand, since the calorific value differs depending on the gas type of the supply gas, the absolute value of the maximum thermoelectromotive force and the absolute value of the thermoelectromotive force in the incomplete combustion state differ depending on each supply gas. Are substantially the same regardless of the supply gas of any gas type. Therefore, when oven cooking is started, the thermoelectromotive force output from the thermocouple is monitored, and the thermoelectromotive force during ignition of the oven burner being monitored is the maximum thermoelectromotive force that is updated during cooking . If the incomplete combustion of the oven burner is determined based on whether or not it falls by a predetermined value or more, the combustion failure can be determined at an early stage regardless of the gas type of the supply gas.

  In the heating cooker, preferably, the control unit increases the rotational speed of the circulation fan in the initial ignition stage of the oven burner.

  If the circulation fan is rotated at high speed in the early stage of ignition, the amount of external air taken in will increase, and even if there is a partial blockage, an air-rich state can be formed, so the maximum thermoelectromotive force can be obtained in a short time. it can.

  As described above, according to the present invention, in order to determine incomplete combustion of the oven burner, there is no need to manufacture a control unit for each of a plurality of gas types having different components, and the control unit corresponding to the gas type. It is not necessary to change the setting of the threshold value of the thermoelectromotive force in Thereby, it is excellent in workability | operativity and can provide a highly versatile heating cooker at low cost.

It is a schematic cross-sectional perspective view which shows an example of the heating cooker which concerns on embodiment of this invention. It is a cross-sectional principal part perspective view which shows the back part of the heating cooker which concerns on embodiment of this invention. It is a block diagram in the heating cooker which concerns on embodiment of this invention. It is a graph which shows each combustion characteristic at the time of using 3 types of gas types with the heating cooker which concerns on embodiment of this invention, (a) is a combustion characteristic at the time of using city gas, (b) ) Is a combustion characteristic when propane gas is used, and (c) is a combustion characteristic when butane gas is used. It is a flowchart which shows an example of control operation of the heating cooker which concerns on embodiment of this invention.

  FIG. 1 is a schematic cross-sectional perspective view showing an example of a heating cooker according to the present embodiment. This cooking device is a built-in gas stove in which a stove body 11 is incorporated in a state of being dropped into an opening of a countertop 10 of a system kitchen. The oven incorporated in the gas stove is located below the countertop 10 and has a heating chamber (oven cabinet) 3a for containing the food to be cooked, and a combustion chamber 3b provided therebelow. In this specification, the direction in which the door 32 side and the back side of the heating chamber 3a face each other is referred to as the front-rear direction, the width direction of the heating chamber 3a is referred to as the left-right direction, and the height direction of the heating chamber 3a is referred to as the up-down direction.

  The heating chamber 3a is horizontally long on the left side of the stove main body 11, and by opening and closing the door 32 of the front panel, an object to be cooked can be taken in and out of the heating chamber 3a.

  Specifically, when the door 32 is rotated forward, the plate 13 can be pulled out. For example, after an object to be cooked such as fish is placed on the plate 13, the door 32 is rotated backward. By doing so, the object to be cooked is accommodated in the heating chamber 3a. In addition, the front panel of the door 32 is provided with a point fire switch 70 for performing oven cooking and an operation unit (not shown) that opens forward by pressing the front panel. Has a cooking menu switch for selecting fish dishes or fried food dishes.

  The heating chamber 3a has an upper wall 33 that constitutes a ceiling portion, a lower wall 34 that partitions the lower combustion chamber 3b, left and right side walls 35, and a rear (back side) rear wall 36. The door 32 is closed so as to be openable forward. In addition, a large number of exhaust outlets 33 a communicating with the exhaust port 50 through the exhaust passage 5 formed above the upper wall 33 are formed in the rear central portion of the upper wall 33 of the heating chamber 3 a.

  As shown in FIGS. 1 and 2, the rear wall 36 of the heating chamber 3a is formed with a large number of suction ports 31 for taking in the hot air in the heating chamber 3a in the center, and a large number of suction ports 31 on both the left and right sides. An air outlet 21 is formed. Further, a heat shield plate 38 (see FIG. 2) is attached to the rear surface of the rear wall 36 excluding the region where the suction port 31 between the left and right outlets 21 is formed, being separated from the rear wall 36. Yes. A hot air passage 44 for supplying hot air of the combustion exhaust gas generated in the combustion chamber 3b to the heating chamber 3a is formed behind the heat shield plate 38.

  The combustion chamber 3b includes a lower wall 34 that constitutes a ceiling wall of the combustion chamber 3b, a bottom surface opposed to the lower wall 34, left and right side surfaces, and a heat shield plate attached to the rear surface of the rear wall 36. 38 and a hot-air passage forming member 45 having a rear wall facing surface 45b (see FIG. 2) disposed opposite to it.

  A flat Bunsen type oven burner 43 is disposed behind the combustion chamber 3b. The oven burner 43 is made of sheet metal formed by joining two press-molded sheet materials. In the rear part of the oven burner 43, a large number of slit-shaped flame holes that open toward the rear side are arranged at predetermined intervals in the left-right width direction. In addition, an ignition electrode and a thermocouple, which will be described later, are arranged in the vicinity of the flame hole located at one end in the left-right width direction at the rear part of the oven burner 43. Although not shown, the gas suction part of the oven burner 43 faces an opening opened on the side surface of the combustion chamber 3b, and a nozzle for ejecting supply gas is disposed in the opening.

  The heating cooker has an air intake port communicating with the outside on the lower front surface or the like of the stove body 11, and is configured such that when the circulation fan 6 is rotated, air is taken into the combustion chamber 3b from the outside. Yes. Accordingly, the external air taken in as combustion air and the supply gas are mixed and burned by the oven burner 43, whereby hot air of combustion exhaust gas is generated in the combustion chamber 3b.

  Further rearward of the position where the oven burner 43 is disposed, the hot air passage 44 communicates with the hot air passage 44 surrounded by a heat shield plate 38 and a hot air passage forming member 45 to be described later, and the hot air generated in the combustion chamber 3b is in the hot air passage. 44.

  The hot air passage forming member 45 is in close contact with the heat shield plate 38 in such a manner as to surround the upper and left sides of the suction port 31 from the rear wall facing surface 45b located behind the heat shield plate 38, and the lower part thereof is in the combustion chamber 3b. It is open. Furthermore, an opening 45a for sucking hot air through the hot air passage 44 by the circulation fan 6 described later is formed at a position facing the suction port 31 of the rear wall facing surface 45b.

  As shown in FIGS. 1 and 2, a circulation fan case 60 is disposed at the rear of the rear wall facing surface 45b of the hot air passage forming member 45 so as to surround the hot air passage 44 formed at the rear of the heating chamber 3a. Has been. The circulation fan case 60 is closed at the rear surface except for the insertion portion through which the rotation shaft of the motor 4 is inserted, and the front end portion of the upper surface, the bottom surface, and both side surfaces are joined to the peripheral edge of the rear wall 36 and closed. Has been. As a result, a circulation passage 61 is formed which communicates with the hot air passage 44 through the opening 45a and communicates with the air outlets 21 provided on the left and right sides of the rear wall 36 of the heating chamber 3a. A circulation fan 6 for forcibly circulating hot air in the heating chamber 3a is disposed in the circulation passage 61.

  The circulation fan 6 of the present embodiment is a suction-type circulation fan that is disposed downstream of the oven burner 43 in the hot air flow path. This circulation fan 6 is fixed to the tip of the rotating shaft of the motor 4 located at the rear, and corresponds to the formation area of the suction port 31 at the center of the rear wall 36 and the opening 45a of the rear wall facing surface 45b. Is installed. Therefore, when the motor 4 is energized to rotate the circulation fan 6, hot air in the heating chamber 3 a is sucked into the circulation passage 61 through the suction port 31 formed in the rear wall 36 and the lower combustion chamber. The hot air generated in 3b passes through the hot air passage 44 and is sucked into the circulation passage 61 from the opening 45a. And the sucked hot air is sent out into the heating chamber 3a from the blower outlets 21 located on the left and right sides of the rear wall 36. As a result, hot air is forcibly circulated in the heating chamber 3a, the temperature in the heating chamber 3a is rapidly increased, and the temperature can be made uniform efficiently. Fish or meat contained in the heating chamber 3a Etc. can be cooked in an oven.

  A motor chamber 40 in which the motor 4 is accommodated is provided behind the circulation fan case 60 constituting the circulation passage 61, and as shown in FIG. A supply cylinder 42 that is open to the outside is connected, and cooling external air can be taken in via the supply cylinder 42.

  A cooling fan 7 is disposed between the circulation fan case 60 and the motor 4. The cooling fan 7 is fixed to an intermediate portion in the axial direction of the rotating shaft of the motor 4. Between the cooling fan 7 and the motor 4, A cooling fan case 41 having a rear surface having an opening 41a in the center for cooling the motor 4 by the rotation of the cooling fan 7 is disposed.

  The cooling passage 8 communicates with the motor chamber 40 via the opening 41 a of the cooling fan case 41, but is separated from the circulation passage 61 by the circulation fan case 60 so as to be disconnected. The cooling air is configured not to be sent into the hot air passage 44. Thereby, the temperature fall of the hot air by cooling air is prevented.

  As described above, the exhaust passage 5 communicating with the exhaust outlet 33a and the exhaust port 50 is formed at the upper rear of the upper wall 33 constituting the ceiling portion of the heating chamber 3a. Further, the downstream end of the exhaust passage 5 and the downstream end of the cooling passage 8 are connected to a cylindrical exhaust duct 9 constituting the exhaust port 50. Thus, the cooling passage 8 is disposed in a state of being separated and separated from the exhaust passage 5 by the partition plate 52, and the exhaust from the exhaust passage 5 and the cooling air from the cooling passage 8 are They merge on the downstream side of the downstream ends of the passages 5 and 8 and are discharged to the outside through a single exhaust port 50.

  Behind the exhaust passage 5, an afterburner 83 having a ceramic combustion plate for burning and burning oil smoke is disposed with the combustion surface facing upward. An exhaust temperature thermistor 55 for detecting the temperature of the exhaust gas flowing through the exhaust passage 5 is disposed between the exhaust outlet 33a and the after burner 83. The temperature signal detected by the exhaust temperature thermistor 55 is output to a control unit C described later via a wiring (not shown).

  Accordingly, when the object to be cooked is accommodated in the heating chamber 3a and the circulation fan 6 is rotationally driven by the motor 4, external air is taken in. In this state, when the gas is supplied to the oven burner 43 and ignited, the oven burner 43 The hot air of the generated combustion exhaust gas is sent into the heating chamber 3a, and the hot air starts to circulate through the heating chamber 3a forcibly. During oven cooking, while the circulation fan 6 is rotating, external air is taken into the combustion chamber 3b, so that a part of the hot air in the heating chamber 3a serves as exhaust including oil smoke generated from the cooking object. The gas is discharged from the exhaust outlet 33a of 33 to the exhaust passage 5. When the afterburner 83 is burned, the oil smoke is heated and burned while passing through the exhaust passage 5.

  FIG. 3 is a block diagram of the heating cooker according to the present embodiment. Branch pipes L1 and L2 branched from the gas supply pipe L are connected to the oven burner 43 and the after burner 83, respectively. A main valve 403 that is opened and closed by pressing of the fire extinguishing switch 70 is arranged in the gas supply pipe L. It is installed. Each of the branch pipes L1 and L2 includes a safety valve 404 and 804 that are electromagnetic valves that are opened when the ignition of the burners 43 and 83 is started, and an electromagnetic valve that adjusts the amount of gas supplied to the burners 43 and 83, respectively. Flow rate adjustment valves 405 and 805 are provided. The opening degree of these safety valves 404 and 804 and flow rate adjustment valves 405 and 805 is adjusted in accordance with a signal from the control unit C.

  In the vicinity of the flame holes of the burners 43 and 83, ignition electrodes 401 and 801 are disposed. The ignition electrodes 401 and 801 are subjected to a spark discharge when a high voltage is applied from the igniter 100.

  Further, thermocouples 402 and 802 are disposed in the vicinity of the flame holes of the burners 43 and 83, respectively, so that the heat-sensitive part at the tip thereof faces the flame hole. Specifically, the thermosensitive portions of the thermocouples 402 and 802 are disposed at positions where the internal flame of the combustion flame is formed when the combustion flame is formed in the normal combustion state. A thermoelectromotive force is generated by heating the thermocouples 402 and 802 with the combustion flame, and the generated thermoelectromotive force is output to the control unit C.

  The control unit C is an electronic unit including a CPU, a ROM, a RAM, and the like, and operates with power supplied from the power supply circuit 900. And the control unit C performs the heating cooking with respect to a to-be-cooked object according to operation of the operation unit 700 by a user. Although not shown, the control unit C performs motor cooking according to the operation of the operation unit 700, so that a motor drive circuit, a switch circuit, an igniter circuit, a solenoid valve drive circuit, a thermocouple circuit, a thermistor circuit, a timer Circuit, buzzer drive circuit, etc.

  The operation unit 700 includes a cooking start switch 701 for starting cooking, a cooking mode selection switch 702 for performing manual cooking and automatic cooking according to the type of cooking, and a cooking menu switch 703 for selecting a cooking type such as fish dishes. Further, a temperature setting switch 704 for setting the cooking temperature, a cooking time setting switch 705 for setting the cooking time, and the like are provided.

  FIG. 4 shows a normal combustion state where the exhaust outlet 33a is not closed and an incomplete combustion state where a part of the exhaust outlet 33a is intentionally closed using the heating cooker of the present embodiment. It is a graph which shows the change of the thermoelectromotive force of the thermocouple 402 when supplying different gas types and burning the oven burner 43, (a) is a combustion characteristic when supplying city gas (13A), ( b) shows the combustion characteristics when propane gas is supplied, and (c) shows the combustion characteristics when butane gas is supplied. In each graph, the solid line indicates the combustion characteristic in the normal combustion state, and the broken line indicates the combustion characteristic in the incomplete combustion state. In this cooking device, a chromel-constantan thermocouple (standard internal resistance: 20.8 ± 3 mΩ, generated electromotive force: 15 mV or more / heat-sensitive part temperature 650 ° C.) is used. The gas supply amount is set to a fixed amount that forms a combustion flame with the maximum thermal power in a normal combustion state.

  As shown in the figure, the maximum thermoelectromotive force of the thermocouple during ignition is about 12 to about 13 mV for city gas, about 20 mV for propane gas, and about 17 mV for butane gas, and the absolute value depends on the gas type. Although it is different, it can be seen that there is no difference in the maximum thermoelectromotive force even if the exhaust outlet 33a is not blocked or partially blocked. This is because the oven burner 43 is disposed in the combustion chamber 3b separate from the heating chamber 3a, and external air is taken in by the circulation fan 6. This is because the thermocouple 402 is heated by the combustion flame until a certain time elapses, and a maximum thermoelectromotive force equivalent to that in the normal combustion state is obtained. If a complete blockage in which external air cannot be taken in occurs, the oven burner 43 will misfire in a short time, so the misfire may be detected by the absolute value of the thermoelectromotive force, or the oven may be detected by other misfire detection means. The gas supply to the burner 43 may be stopped.

  On the other hand, when partial blockage occurs, the temperature of each part rises as it reaches the steady state, and the ventilation resistance increases and the amount of external air taken in decreases. It becomes difficult to form, and the shape of the combustion flame collapses and a partial lift of the combustion flame occurs. Therefore, within a short time after ignition, even if the thermocouple 402 is heated in the high temperature part of the inner flame of the combustion flame, it will be burned by the low temperature combustion flame due to lack of oxygen, and the thermoelectromotive force will decrease. To do. The thermoelectromotive force when this incomplete combustion state occurs also varies depending on the gas type, and is about 3 mV for city gas, about 9 mV for propane gas, and about 7 to about 9 mV for butane gas. Therefore, in order to determine the combustion failure based on the absolute value of the thermoelectromotive force, it is necessary to set different threshold values for each gas type.

  However, as shown in the table below, the difference between the maximum thermoelectromotive force and the thermoelectromotive force after the incomplete combustion state occurs is the difference between any gas type and the degree of blockage. , About 8 mV to about 11 mV.

  Therefore, when these three types of supply gases having different calorific values are used, if the thermoelectromotive force is reduced by about 7 to 8 mV from each maximum thermoelectromotive force, the oven burner 43 burns in an incomplete combustion state with any gas species. It can be determined that there is a risk of doing so. In addition, in some cooking devices that perform oven cooking, the oven burner 43 is extinguished during cooking to adjust the temperature in the heating chamber 3a. Since clogging of the exhaust outlet 33a and the like due to oily smoke is likely to occur during cooking, such a heating cooker causes poor combustion not only at the start of oven cooking but also during the oven burner 43 is ignited during temperature adjustment. If determined, it is possible to prevent the oven burner 43 from burning in an incomplete combustion state at an early stage.

  Next, an example of the control operation in the case of performing oven cooking using the heating cooker of the present embodiment will be described based on the flowchart shown in FIG. In this cooking device, in order to adjust the temperature during cooking in the oven, when the exhaust temperature detected by the exhaust temperature thermistor 55 becomes higher than the set temperature by a predetermined temperature or more, the safety valve 404 is closed and the oven burner 43 is closed. The temperature is controlled so that the oven burner 43 is re-ignited when the temperature becomes lower than the set temperature by a predetermined temperature or more. The gas supply amount to the oven burner 43 during ignition including the first ignition process is the maximum. It is set to a fixed amount that provides thermal power.

  To perform oven cooking, the user rotates the door 32 forward, places an object to be cooked such as fish or meat on the plate 13 taken out from the heating chamber 3a, and rotates the door 32 backward. Then, after closing the front opening part of the heating chamber 3a, when the point fire switch 70 is pressed (step ST1), power is supplied from the power supply circuit 900 and the control unit C starts operating, and the main valve 403 Opens. Then, for example, when the user selects automatic cooking with the cooking mode selection switch 702 of the operation unit 700, further selects the fish cooking switch with the cooking menu switch 703, and turns on the cooking start switch 701 (steps ST2 to ST2). ST3) An ON signal is input to the control unit C, and oven cooking is started. At this time, the control unit C determines in advance whether or not the exhaust temperature detected by the exhaust temperature thermistor 55 is lower than the set temperature by a predetermined temperature (for example, −4 ° C.) (step ST4). That is, when oven cooking is performed continuously, the inside of the heating chamber 3a may already be heated to a set temperature or higher. Therefore, if the exhaust temperature detected by the exhaust temperature thermistor 55 is not lower than the set temperature by a predetermined temperature or more (No in step ST4), cooking can be started without igniting the oven burner 43.

  When the exhaust temperature detected by the exhaust temperature thermistor 55 is lower than the set temperature by a predetermined temperature or more (Yes in step ST4), the control unit C starts the timer and energizes the motor 4 to supply the circulation fan 6 and the cooling fan. 7 is rotated at a predetermined rotational speed (step ST5). Thereby, external air is taken into the combustion chamber 3b. In this embodiment, the rotational speed of the circulation fan 6 is the same before and after ignition. However, the rotational speed at the initial stage of ignition may be increased more than the rotational speed after the ignition of the oven burner 43 is completed. According to this, even if partial blockage occurs, an air-rich state can be formed at the time of ignition, so that the maximum thermoelectromotive force can be obtained early.

  When the circulation fan 6 is rotationally driven at a predetermined number of revolutions (Yes in step ST6), the safety valves 404 and 804 are opened, the flow rate adjusting valve 405 is at the maximum heating power, and the flow rate adjusting valve 805 is the standard heating power ( The valve is opened at an opening degree of about 80% of the maximum thermal power), and a high voltage is further applied from the igniter 100 to the ignition electrodes 401 and 801, and a spark is discharged for a predetermined ignition detection time (for example, 10 seconds) (step ST7). ). Then, monitoring of the thermoelectromotive force generated when the thermocouple 402 is heated by the combustion flame is started.

  When the thermoelectromotive force (Vx) of the thermocouple 402 being monitored is input to the control unit C, the control unit C first starts the thermoelectromotive force at an ignition level (for example, 2.5 mV) within a predetermined ignition detection time. Is determined (step ST8). Thereby, ignition failure can be determined. If a thermoelectromotive force higher than the ignition level cannot be obtained even after a predetermined ignition detection time has elapsed (No in step ST8, Yes in step ST17), the igniter 100 is turned off (step ST18), and the buzzer 600 After notifying the abnormality (step ST19), the main valve 403 is closed and the motor 4 is stopped to end the ignition process (step ST20). Note that the ignition detection may be performed by a frame rod.

  On the other hand, when the thermoelectromotive force at the ignition level is obtained within the predetermined ignition detection time (Yes in step ST8), the igniter 100 is turned off (step ST9), and the maximum value (Vmax) of the monitored thermoelectromotive force (Vmax). Is updated in the memory (step ST10). Next, it is determined whether or not the monitored thermoelectromotive force (Vx) during ignition is reduced by a predetermined value (for example, 7 mV) or more with respect to the acquired maximum thermoelectromotive force (Vmax) (step ST11). ).

  When the monitored electromotive force (Vx) during ignition of the oven burner 43 decreases by a predetermined value or more with respect to the maximum thermoelectromotive force (Vmax) (Yes in step ST11), the control unit C After determining that 43 is incompletely burned and notifying abnormality (step ST19), the main valve 403 is closed, the motor 4 is stopped, and the ignition process is terminated (step ST20). Thereby, even if any gas type is used, the single control unit C can prevent the combustion failure of the oven burner 43 without setting a plurality of determination thresholds. In the present embodiment, the afterburner 83 is disposed in the vicinity of the exhaust port 50, and since a ceramic planar burner is used, it is difficult for combustion failure to occur. Although it is sufficient to determine the combustion failure based only on the electromotive force, the combustion failure may be determined using both thermoelectromotive forces of the thermocouple 402 and the thermocouple 802.

  On the other hand, if the thermoelectromotive force (Vx) of the monitored thermocouple 402 has not decreased by a predetermined value or more with respect to the maximum thermoelectromotive force (Vmax) (No in step ST11), the control unit C selects Temperature control is performed based on the cooking menu setting.

  In this temperature control, first, it is determined whether or not a predetermined heating time for fish dishes selected by the cooking menu switch 703 has elapsed (step ST12), and if the heating time has not elapsed (in step ST12, No), it is determined whether the exhaust temperature detected by the exhaust temperature thermistor 55 is higher than the set temperature for fish dishes selected by the cooking menu switch 703 by a predetermined temperature (for example, + 4 ° C.) or more (step ST13). . Then, until the exhaust temperature becomes higher than the set temperature by a predetermined temperature or more (No in step ST13), the monitored thermoelectromotive force (Vx) and the maximum thermoelectromotive force (Vmax) registered in the memory. And incomplete combustion of the oven burner 43 is determined while updating the maximum thermoelectromotive force (Vmax) (steps ST10 to ST12). In the present embodiment, during ignition, the oven burner 43 is supplied with a certain amount of gas capable of obtaining the maximum heating power. Therefore, incomplete combustion occurs due to partial blockage, as shown in FIG. As described above, the maximum thermoelectromotive force (Vmax) is acquired until a predetermined time elapses after the first ignition of the oven cooking, and thereafter, the thermoelectromotive force (Vx) decreases. For this reason, the maximum thermoelectromotive force (Vmax) may be obtained only from the thermoelectromotive force (Vx) until a predetermined time elapses from the first ignition. However, for example, the maximum thermoelectromotive force (Vmax) is set in consideration of a case where ignition is performed with a gas supply amount at which medium thermal power is obtained in the first ignition processing, and a gas supply amount is increased in the reignition processing in temperature adjustment. It is preferable to update from time to time based on the thermoelectromotive force (Vx) during ignition being monitored.

  When the exhaust gas temperature becomes higher than the predetermined temperature (Yes in step ST13), the safety valve 404 that supplies gas to the oven burner 43 is closed, and the oven burner 43 is extinguished (step ST14). Thereby, since hot air is not sent into the heating chamber 3a from the combustion chamber 3b, the temperature in the heating chamber 3a can be lowered. At this time, since the thermocouple 402 is not beaten by the combustion flame, the thermoelectromotive force is reduced, but incomplete combustion due to the thermoelectromotive force is not determined during extinguishing of the oven burner 43 with the safety valve 404 closed. Misjudgment is prevented. During the extinguishing of the oven burner 43, the rotational speed of the circulation fan 6 may be reduced or stopped in order to reduce the exhaust discharged from the heating chamber 3a to the exhaust passage 5.

  After the oven burner 43 is extinguished, the control unit C determines that the exhaust temperature detected by the exhaust temperature thermistor 55 is a predetermined temperature (for example, −4 ° C.) or higher than the set temperature for fish dishes selected by the cooking menu switch 703. It is determined whether it has become low (step ST15).

  When the exhaust gas temperature becomes lower than the predetermined temperature (Yes in step ST15), it is determined whether or not the heating time has elapsed (step ST16). And if heating time has not passed, in order to perform the reignition process of the oven burner 43, it transfers to the ignition process after step ST7 mentioned above.

  The control in the temperature adjustment is performed until the heating time set for the fish dish selected by the cooking menu switch 703 is up, and when the predetermined heating time is up (Yes in step ST12 or ST16), The control unit C closes the main valve 403 to extinguish the oven burner 43 and the after burner 83, stops energization of the motor 4, and stops the rotation of the circulation fan 6 (step ST20).

(Other embodiments)
(1) In the above embodiment, in order to circulate hot air in the heating chamber, a suction-type circulation fan is disposed downstream of the oven burner in the hot air flow path, but upstream of the oven burner. A push-type circulation fan may be disposed on the upper side of the oven burner, and a push-type circulation fan may be disposed on the downstream side of the oven burner.

(2) In the above embodiment, the incomplete combustion of the oven burner is determined from the start to the end of the oven cooking. However, the incomplete combustion is performed at an arbitrary timing as long as the oven cooking is being performed. You may judge. For example, as described above, when a partial blockage occurs, the thermoelectromotive force is maximized until a certain time has elapsed since the first ignition at the start of oven cooking. A determination of combustion may be made. Further, since the air outlet and the suction port in the heating chamber may be blocked during oven cooking, incomplete combustion may be determined during the oven cooking.

3a Heating chamber 3b Combustion chamber 43 Oven burner 4 Motor 6 Circulating fan 402, 802 Thermocouple C Control unit

Claims (2)

An oven burner that generates hot air by burning the supply gas;
A heating chamber for heating the cooking object;
A circulation fan that takes in external air that burns the oven burner and circulates hot air generated by the oven burner to the heating chamber;
A thermocouple facing the flame hole of the oven burner;
A control unit capable of determining incomplete combustion of the oven burner, and the control unit monitors the thermoelectromotive force output from the thermocouple when oven cooking is started,
During cooking, the maximum thermoelectromotive force is updated from the thermoelectromotive force during the oven burner ignition being monitored,
A cooking device that determines that the oven burner is in an incomplete combustion state when a thermoelectromotive force during the ignition of the oven burner being monitored is lower than a predetermined value with respect to the maximum thermoelectromotive force. The heating cooker according to claim 1, wherein
The said control unit is a heating cooker which increases the rotation speed of the said circulation fan in the ignition initial stage of the said oven burner.

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