JP5979990B2 - Induction heating cooker - Google Patents

Description

  The present invention relates to an induction heating cooker that induction-heats an object to be heated such as a pan or a frying pan using a heating coil.

In recent years, induction heating cookers have been widely used because they have been recognized for their excellent characteristics of safety, cleanliness, and high efficiency. In order to detect the temperature of the object to be heated, this type of induction heating cooker has been proposed that includes an infrared sensor that detects infrared energy emitted from the object to be heated (for example, Patent Document 1). reference).
The infrared sensor is provided below the top plate, receives infrared rays emitted from the object to be heated from an infrared incident region provided on the top plate, and outputs a signal that changes according to the temperature of the object to be heated. The heating cooker described in Patent Document 1 reduces the output of the heating coil or stops heating when the amount of increase from the value of the initial detection value becomes equal to or greater than a predetermined value using an infrared sensor.

WO2009 / 022475 (FIG. 8)

  In the technique described in Patent Document 1 described above, the output of the heating coil is controlled by the amount of change in the value of the infrared sensor immediately after the start of heating, but the temperature of the heated object at the start of heating is, for example, about 150 ° C. When the temperature is high and heating is performed until the control by the amount of change of the infrared sensor is applied, the object to be heated becomes, for example, 300 ° C. or more, and the object to be heated is subject to deterioration such as deformation due to heat. Oil may ignite.

  The present invention has been made to solve the above-described problems, and an object thereof is to obtain an induction heating cooker that controls the output of a heating coil in accordance with the amount of change in temperature of an object to be heated before the start of heating. And

An induction heating cooker according to the present invention includes a top plate on which an object to be heated is placed, a heating coil disposed below the top plate, DC power is converted into high frequency power, and high frequency current is supplied to the heating coil. And an inverter circuit that induction-heats the object to be heated, a temperature sensor that detects the temperature of the object to be heated via the top plate, and a control device that controls the output of the inverter circuit. The temperature of the top plate on which the object to be heated is placed is read from the temperature sensor for a certain time before the start of heating, and the amount of change in temperature is calculated for a certain time. in which heating by controlling the output of the inverter circuit is to so that is started in accordance with the amount of change.

  According to the present invention, the temperature of the top plate on which the object to be heated is placed is read from the temperature sensor for a certain period of time before the start of heating with the set thermal power, and the amount of change in temperature over a certain period of time is calculated. At the start, the output of the inverter circuit is controlled according to the amount of change. As a result, the object to be heated is not overheated. Therefore, the object to be heated can be prevented from being deteriorated by heat and ignition of oil in the object to be heated.

The perspective view which shows the external appearance of the induction heating cooking appliance which concerns on Embodiment 1. FIG. The top view which shows the induction heating cooking appliance of FIG. 1 seeing from upper direction. The block diagram which shows the circuit structure of the induction heating cooking appliance of FIG. The flowchart which shows the basic operation | movement until it enters into heating operation in the induction heating cooking appliance of FIG. The flowchart which shows operation | movement of the induction heating cooking appliance which concerns on Embodiment 1. FIG. The figure which shows the change of the detected temperature of the temperature sensor in the pot temperature determination time in the induction heating cooking appliance which concerns on Embodiment 1. FIG. The figure which shows the change of the detected temperature of the temperature sensor in the pot temperature determination time in the induction heating cooking appliance which concerns on Embodiment 3. FIG.

Embodiment 1 FIG.
1 is a perspective view showing an appearance of an induction heating cooker according to Embodiment 1. FIG.
The induction heating cooker 1 shown in the figure includes, for example, a top plate 14 at the top of a box-shaped main body case 2C, an annular left / right heating coil (not shown) in the main body case 2C, and the main body case 2 Is provided with a grill cooker 3 having a roaster function and an oven function.

  The top plate 14 is formed of heat-resistant tempered glass, and is attached to the main body case 2 </ b> C in a state where the peripheral edge portion is mounted on the frame-shaped metal frame 15. The top plate 14 is printed so that the inside is not visible on the back surface except for the central display panel 16, left / right display panels 17L, 17R and left / right display portions 18L, 18R, which will be described later. Further, on the surface of the top plate 14, a left heating port 2L and a right heating port 2R indicating the placement position of an object to be heated such as a pan or a frying pan are displayed by a method such as printing. The left heating coil is disposed to face the left heating port 2L displayed on the top plate 14, and the right heating coil is disposed to face the right heating port 7R.

  An upper surface operation unit 19 for performing operations such as the start of a heating operation is provided at the front edge of the metal frame 15, and a front operation unit 13 is provided on the right side of the front surface of the main body case 2C. The front operation unit 13 is provided with a main power switch 11 and power adjustment dials 12L and 12R. The power adjustment dial 12L adjusts the heating power during induction heating in the left heating port 2L, and the power adjustment dial 12R adjusts the heating power during induction heating in the right heating port 2R. In addition, the rated power consumption (maximum power consumption) of this induction heating cooking appliance 1 is 5800W, for example.

  The above-mentioned central display panel 16 is disposed in the vicinity of the rear surface of the front center of the top plate 14 and includes a liquid crystal display substrate that displays set values of various cooking conditions, alarms, and abnormality information. The left display panel 17L is a liquid crystal display substrate that is disposed close to the back surface of the top plate 14 on the front side of the left heating port 2L, and displays a thermal power value and a thermal power level (strong, medium, weak) during induction heating. I have. The right display panel 17R is disposed close to the back surface of the top plate 14 on the front side of the right heating port 2R. Like the left display panel 17L, the heating power value and the heating power level (strong, medium, weak) during induction heating are arranged. Etc. are provided. The left display unit 18L displays the heating time of the left heating port 2L and the oil temperature during oil cooking with liquid crystal characters and a plurality of light emitting diodes (light emitting bodies). As with the left display portion 18L, the right display portion 18R displays the heating time of the right heating port 2R and the oil temperature during oil cooking with liquid crystal characters, a plurality of light emitting diodes (light emitters), and the like.

  Between the rear edge of the metal frame 15 and the top plate 14, there are an intake port 20 for taking in indoor air into the main body case 2C, and an exhaust port 21 for discharging air taken into the main body case 2C. Is provided. The indoor air is taken into the main body case 2C from the air inlet 20 by driving a blower (not shown) installed in the main body case 2C, and the control device that controls the overall operation of the induction heating cooker 1 is cooled. Thereafter, the left and right heating coils 2LC and 2RC are cooled and discharged from the exhaust port 21.

  The grill cooker 3 has a front opening grill compartment 22 provided adjacent to the front operation unit 13 in the main body case 2C, and a handle 26A at the lower front part for opening and closing the front opening of the grill compartment 22. The grill door 26 is placed on the bottom of the grill cabinet 22 and interlocked with the front and rear movements of the grill door 26. The saucer 23 is detachably placed in the saucer 23, and an object 25 such as fish is placed on the upper side. For example, a radiation type sheathed heater (not shown) installed in the grill cabinet 22, and a smoke removal device (not shown) provided at the rear of the grill cabinet 22. .

  The sheathed heater in the grill cabinet 22 is horizontally arranged near the ceiling and bottom surface of the grill cabinet 22, and is configured to heat the grill net 24 from above and below. The smoke removing device described above includes an exhaust duct (not shown) provided between the inner wall of the grill cabinet 22 and the exhaust port 21, a sheathed heater installed on the inlet side of the exhaust duct, A catalyst that is installed in the exhaust duct and promotes redox action by heating the sheathed heater, and a smoke that is disposed in the exhaust duct and that is generated during cooking of the food to be cooked 25 such as fish. It is comprised by the sirocco fan which sucks through and exhausts from the exhaust port 21.

Next, the configuration of the upper surface operation unit 19 will be described with reference to FIG.
FIG. 2 is a plan view showing the induction cooking device of FIG. 1 as viewed from above.
In FIG. 2, the upper surface operation unit 19 is disposed in a strip shape in the lateral direction at the front edge of the metal frame 15 as described above. The upper surface operation unit 19 includes, from the left side, a left heating port operation unit 27 for operating the heating operation of the left heating port 2L, a grill operation unit 29 for operating the heating operation of the grill cooker 3, and a right side. A right heating port operation section 28 for operating the heating operation of the heating port 2R is provided.

  Among these, the left heating port operation unit 27 includes a fried food button 27a, a frying pan preheating button 27b, and an on / off button 27c. The right heating port operation unit 28 includes a deep-fried food button 28a, a frying pan preheating button 28b, and an on / off button 28c. The grill operation unit 29 includes a grill menu button 29a, a start / stop button 29b, a left arrow button 29c, a right arrow button 29d, a time minus button 29e, and a time plus button 29f.

  In addition, the kind and arrangement | positioning of each button which comprise the upper surface operation part 19 shown in FIG. 2 show an example, and are not limited to this.

Next, the circuit configuration of the induction heating cooker 1 will be described with reference to FIG.
FIG. 3 is a block diagram showing a circuit configuration of the induction heating cooker of FIG.
In FIG. 3, when a commercial power supply voltage is applied by turning on the main power switch 11 of the front operation unit 13, the power supply circuit 31 generates a predetermined constant voltage / constant current and supplies it to the control device 32. The control device 32 includes, for example, a microcomputer having an input unit, an output unit, a storage unit, and a CPU (arithmetic control unit). In the storage unit, energization control programs corresponding to various cooking menus are stored in advance.

  The inverter circuit 33L generates a high-frequency current based on the control of the control device 32, and supplies the high-frequency current to a resonance circuit composed of the left heating coil 2LC and the resonance capacitor C. The inverter circuit 33R generates a high-frequency current based on the control of the control device 32 as described above, and supplies the high-frequency current to a resonance circuit including the right heating coil 2RC and a resonance capacitor.

  The grill heater drive circuit 34 supplies current to the sheathed heater 34 </ b> H disposed in the grill warehouse 22 based on energization control from the control device 32. The display unit drive circuit 35 displays the control information from the control device 32 on the central display panel 16, the left / right display panels 17L, 17R, and the left / right display units 18L, 18R. The catalyst heater drive circuit 36 energizes the sheathed heater that heats the catalyst described above. The voice synthesizer 38 notifies the user with operation voices generated electronically from the speaker 39 when an operation guidance or abnormality occurs.

  The temperature detection circuit 40 detects the temperature of an object to be heated such as a pan or a frying pan on the top plate 14 heated by the left and right heating coils 2LC and 2RC, the temperature of the top plate 14, the ambient temperature in the grill cabinet 22, and the like. Temperature detection information is received from a plurality of temperature sensors (not shown) for detection, and the temperature detection result is sent to the control device 32. The temperature sensor described above may be either a non-contact type infrared sensor or a contact type thermistor, or may be used in combination.

  The above-described control device 32 will be described in detail when explaining the operation. Before starting the heating after the determination of the size and material of the object to be heated (load determination), a pan for checking whether the object to be heated is hot or not. Perform temperature judgment. For example, after determining the load, the control device 32 stops the output of the inverter circuits 33L and 33R for a certain time (pan temperature detection time: for example, 10 seconds), and the top plate on which the object to be heated is placed. The temperature of 14 is read from the temperature sensor, the amount of change in temperature in 10 seconds is calculated, and the outputs of the inverter circuits 33L and 33R are controlled according to the amount of change when heating is started. For example, a contact type thermistor is used as the temperature sensor, and the temperature sensor is installed so as to be in contact with the back surface of the top plate 14.

  Next, operation | movement of the induction heating cooking appliance 1 comprised as mentioned above is demonstrated. First, the basic operation of the induction heating cooker 1 will be described with reference to FIG. 4, and then the pan temperature determination for determining whether the object to be heated is high will be described with reference to FIGS. 5 and 6.

FIG. 4 is a flowchart showing a basic operation until the heating operation is started in the induction heating cooker of FIG.
When the user turns on the main power switch 11 of the front operation unit 13 (ST1), the voltage of the commercial power supply is applied to the power supply circuit 31. At this time, the power supply circuit 31 generates a predetermined constant voltage / constant current from the voltage of the commercial power supply and supplies it to the control device 32 as a control power supply. When the control power is applied, the control device 32 reads temperature information from the temperature detection circuit 40, and the temperature of the main part of the induction heating cooker 1 (the top plate 14, the inside of the grill cabinet 22, etc.) becomes abnormally high. It is checked whether it is not (ST2).

  When no abnormality is found, the control device 32 displays characters indicating that cooking can be started on the central display panel 16 via the display unit driving circuit 35 and also displays the content displayed on the central display panel 16 as a speech synthesizer 38. Is notified by voice (ST3).

  Thereafter, the control device 32 displays, on the central display panel 16, characters that prompt the selection of the heating source in characters (ST4). Then, the control device 32 determines whether or not the grill cooker 3 has been selected (ST5). If the grill cooker 3 has not been selected, whether or not one of the left and right heating ports 2L and 2R has been selected. Is determined (ST6). When the control device 32 detects an ON operation of the start / stop button 29b of the grill operation unit 29 in ST5, the control device 32 selects the selection of the heating menu of the sheathed heater based on the operation of the grill menu button 29a (ST8). Proceed to select one of the menus of roaster cooking, grill cooking, or oven cooking (ST9A, ST9B, ST9C).

  Further, when the control device 32 detects an ON operation of the on / off button 27c of the left heating port operation unit 27 in ST6, the control device 32 determines that the left heating port 2L is selected, and the control unit 32 of the right heating port operation unit 28 When an on operation of the on / off button 28c is detected, it is determined that the right heating port 2R has been selected, and the process proceeds to selection of an induction heating menu (ST7).

  For example, when detecting the ON operation of the deep-fried food button 27a of the left heating port operation unit 27 in ST7, the control device 32 controls the inverter circuit 33L based on the energization control program for deep-fried food cooking, and the frying pan preheating button. When the on-operation of 27b is detected, the inverter circuit 33L is controlled based on the energization control program for frying pan preheating.

  Further, for example, when the left dial 12L of the front operation unit 13 is rotated, the control device 32 causes the pan of the left heating port 2L to be induction-heated with a heating power corresponding to the rotation angle of the left dial 12L. Then, the inverter circuit 33L is controlled. At that time, the control device 32 displays the heating power on the left display panel 17L.

FIG. 5 is a flowchart showing the operation of the induction heating cooker according to the first embodiment.
The control device 32 controls the inverter circuit 33R so that, for example, a high frequency current of 40 kHz is output when the heating power for load determination is set by the right dial 12R of the front operation unit 13, for example, the load determination is performed. (ST11). First, the control device 32 determines whether or not the object to be heated is placed on the right heating port 2R (ST12), and when it is determined that the object to be heated is placed, the object to be heated can be heated. It is determined whether it is a material (ST13).

  For example, when there is no object to be heated or a small object having a diameter of about 60 mm is placed in the right heating port 2R, the control device 32 determines that the output current of the inverter circuit 33R is equal to or greater than a set threshold value for determining whether there is a load. Therefore, it is determined that there is no load and is not heated (ST15). The material is also determined by a similar determination method. In this case, since the output current of the inverter circuit 33R becomes larger as the non-magnetic material is closer to the non-magnetic material, the control device 32 determines that the output current is less than the set threshold for material determination, and determines that the output current is the material determination. If it is greater than or equal to the set threshold value, it is determined to be non-magnetic. Further, among non-magnetic materials, it is determined whether the material has a certain electrical resistance, such as SUS304, or a material with little electrical resistance, such as aluminum, and when it is determined that the material has little electrical resistance, such as aluminum, heating is performed. Do not do.

  When the control device 32 determines in ST13 that there is a material to be heated in the right heating port 2R, the control device 32 performs pan temperature determination (ST14). At this time, the control device 32 stops the output from the inverter circuit 33R for 10 seconds (pan temperature detection time) and reads the temperature of the top plate 14 on which the object to be heated is placed from the thermistor for 10 seconds. The amount of change in temperature at is calculated.

  For example, as shown in FIG. 6, when the temperature of the top plate 14 detected by the thermistor does not change at 25 ° C. for 10 seconds, the control device 32 estimates that the temperature of the object to be heated is 25 ° C. The output of the inverter circuit 33R is controlled so that the heating power set by the operation of the unit 19 or the front operation unit 13 is obtained. In this case, in the pan temperature determination after the load determination, there is almost no change in the detected temperature of the thermistor and there is almost no increase in the detected temperature of the thermistor, so the temperature of the top plate 14 and the temperature of the object to be heated are substantially the same. Therefore, the output of the inverter circuit 33R is controlled so that the heating power of the right heating port 2R (right heating coil 2RC) becomes the set heating power (ST16).

  In addition, for example, when a frying pan, which is an object to be heated, is heated at the right heating port 2R, and the frying pan is moved to the left heating port 2L and a heating power is set, the control device 32 performs load determination again and performs load determination. The temperature of the top plate 14 detected by the thermistor is read for 10 seconds after the completion, and the amount of change in the detected temperature of the thermistor for 10 seconds is calculated. For example, when the temperature of the top plate 14 of the left heating port 2L immediately after the start of the pan temperature determination is 25 ° C. and the temperature of the frying pan is 100 ° C., the top plate 10 seconds after the start of the pan temperature determination The temperature rises to 30 ° C. under the influence of the heat of the frying pan heated in advance. The amount of change in this case is 5 ° C. (30 ° C.-25 ° C.).

  After calculating the amount of change, the control device 32 determines whether or not 5 ° C., which is the amount of change, is equal to or greater than a set threshold value. When the amount of change (5 ° C.) is equal to or greater than the set threshold value, the control device 32 compares the preset upper limit value (for example, 1 kW) with the set thermal power. When the set thermal power is 1 kW or more, the control device 32 limits the set thermal power to 1 kW and controls the output of the inverter circuit 33L so that the left heating port 2L becomes 1 kW (ST16). Further, when the set thermal power is less than 1 kW, control device 32 controls the output of inverter circuit 33L so as to be the set thermal power (ST16).

  And the control apparatus 32 complete | finishes a heating, after completion | finish of a heating by operation of the upper surface operation part 19, or heating time by a timer (ST17).

  As described above, in the first embodiment, the amount of change is calculated by reading the temperature of the top plate 14 detected by the thermistor for 10 seconds immediately after the load determination, and when the amount of change is equal to or greater than the set threshold, it is set in advance. The upper limit value of the thermal power (for example, 1 kW) is compared with the set thermal power. When the set thermal power is 1 kW or more, the set thermal power is limited to 1 kW and the output of the inverter circuit 33L is controlled. As a result, the object to be heated is not overheated. Therefore, the object to be heated can be prevented from being deteriorated by heat and ignition of oil in the object to be heated.

Embodiment 2. FIG.
In the first embodiment, a thermistor is used as the temperature sensor, but in the second embodiment, a non-contact infrared sensor is used. The infrared sensors are respectively attached below the left and right heating ports 2L and 2R, and detect the temperature of the object to be heated placed on the left and right heating ports 2L and 2R via the top plate 14. Since the detection temperature of the infrared sensor is also affected by the temperature of the top plate 14, when the temperature of the top plate 14 increases, the detection temperature of the infrared sensor also increases.

  Similarly to the first embodiment, when the temperature of the top plate 14 is 25 ° C. and the temperature of the frying pan is 100 ° C., the temperature of the top plate for 10 seconds (pan temperature detection time) immediately after the load determination is increased by 5 ° C. and 30 It is assumed that the temperature of the frying pan has decreased by 10 ° C. to 90 ° C. The change in temperature detected by the infrared sensor at that time is determined by the change in the temperature of the top plate 14 and the change in the temperature of the frying pan.

  For example, if 80% of the detection temperature of the infrared sensor is affected by the top plate 14 and the remaining 20% is affected by the frying pan, the temperature of the top plate is 80% of the rise of 5 ° C., 4 The temperature of the frying pan is estimated to be −20 ° C. at 20% of the 10 ° C. fall, and when combined, the amount of change due to detection by the infrared sensor in 10 seconds is 2 ° C. The change amount is calculated by the control device 32.

  After calculating the amount of change, the control device 32 determines whether or not 2 ° C., which is the amount of change, is equal to or greater than a set threshold value. When the amount of change (2 ° C.) is equal to or greater than the set threshold value, the control device 32 compares the preset upper limit value (for example, 1 kW) with the set thermal power as described above. When the set thermal power is 1 kW or more, the control device 32 limits the set thermal power to 1 kW, and outputs the output of the inverter circuit 33L (or the inverter circuit 33R) so that the left heating port 2L (or the right heating port 2R) becomes 1 kW. Control. Further, when the set thermal power is less than 1 kW, the control device 32 controls the output of the inverter circuit 33L (or the inverter circuit 33R) so as to become the set thermal power.

  As described above, in the second embodiment, the amount of change is calculated by reading the temperature of the top plate 14 detected by the infrared sensor for 10 seconds immediately after the load determination, and when the amount of change is equal to or greater than the set threshold, it is set in advance. The upper limit value (for example, 1 kW) of the generated thermal power is compared with the set thermal power, and when the set thermal power is 1 kW or more, the set thermal power is limited to 1 kW and the output of the inverter circuit 33L is controlled. As a result, the object to be heated is not overheated. Therefore, the object to be heated can be prevented from being deteriorated by heat and ignition of oil in the object to be heated.

Embodiment 3 FIG.
The third embodiment uses a thermistor and an infrared sensor for the temperature sensor. In order to remove the influence of the top plate 14 from the detection temperature of the infrared sensor, the temperature of the top plate 14 is estimated using a thermistor, and the estimated temperature of the top plate 14 is subtracted from the detection temperature of the infrared sensor ( Infrared sensor correction temperature) is used for pot temperature judgment.

  When the temperature of the top plate 14 is close to the temperature of the object to be heated, for example, when the temperature of the top rate 14 is 25 ° C. and the temperature of the pan to be heated is 25 ° C., or the temperature of the top plate 14 is 50 ° C. When the frying pan temperature is 50 ° C., the correction temperature does not change.

  When the temperature of the top plate 14 is lower than the temperature of the object to be heated, for example, when the temperature of the top plate 14 immediately after the load determination is 25 ° C. and the temperature of the frying pan as the object to be heated is 100 ° C. When the temperature of the plate 14 is 50 ° C. and the temperature of the frying pan is 150 ° C., the temperature of the frying pan moves to the top plate 14, so that the temperature detected by the thermistor increases. The infrared sensor is affected by the top plate 14, but does not increase as much as the thermistor, so the correction temperature decreases.

  For example, as shown in FIG. 7, when the temperature of the top plate 14 detected by the thermistor is 25 ° C. and the temperature of the frying pan detected by the infrared sensor is 70 ° C. immediately after the load determination, the correction temperature is 45 ° C. (70 (° C.-25 ° C.). That is, immediately after the load determination, the detection temperature of the thermistor and the detection temperature of the infrared sensor are read to calculate the correction temperature, and after 10 seconds, the detection temperature of the thermistor and the detection temperature of the infrared sensor are read again to calculate the correction temperature, The amount of change is obtained from the previous correction temperature. The amount of change in the correction temperature is calculated by the control device 32.

  After calculating the change amount of the correction temperature, the control device 32 determines whether the change amount is equal to or greater than a set threshold value. When the amount of change is equal to or greater than the set threshold, the control device 32 compares the preset upper limit value (for example, 1 kW) with the set thermal power. When the set thermal power is 1 kW or more, the control device 32 limits the set thermal power to 1 kW, and outputs the output of the inverter circuit 33L (or the inverter circuit 33R) so that the left heating port 2L (or the right heating port 2R) becomes 1 kW. Control. Further, when the set thermal power is less than 1 kW, the control device 32 controls the output of the inverter circuit 33L (or the inverter circuit 33R) so as to become the set thermal power.

As described above, in the third embodiment, the temperature of the top plate 14 is estimated using a thermistor, and the value obtained by subtracting the estimated temperature of the top plate 14 from the detected temperature of the infrared sensor (corrected temperature of the infrared sensor) is the pan temperature. Used for judgment. For this reason, the amount of change in temperature can be calculated accurately.
Further, when the calculated change amount of the corrected temperature is equal to or greater than the set threshold value, a preset upper limit value (for example, 1 kW) of the thermal power is compared with the set thermal power. Then, the output of the inverter circuit 33L is controlled. As a result, the object to be heated is not overheated. Therefore, the object to be heated can be prevented from being deteriorated by heat and ignition of oil in the object to be heated.

Embodiment 4 FIG.
In Embodiments 1 to 3, the amount of change in temperature (or correction temperature) for 10 seconds immediately after the load determination is compared with one set threshold, but the amount of change is compared with a plurality of set thresholds. Is.

  For example, the start condition 1 is when the temperature of the top plate 14 is 25 ° C. and the temperature of the heating object such as the frying pan is 25 ° C., and the start condition 2 is that the temperature of the top plate 14 is 25 ° C. When the temperature is 100 ° C., the start condition 3 is when the temperature of the top plate 14 is 25 ° C. and the temperature of the frying pan is 200 ° C. The amount of change in the detected temperature of the thermistor when determining the pan temperature is as follows. Different.

  In the start condition 1, since the temperature of the top plate 14 and the frying pan are the same, the change amount of the thermistor is 0 ° C. In the start condition 2, since the frying pan is hotter than the top plate 14, the detection temperature of the thermistor rises by 5 ° C., for example. In the start condition 3, since the temperature of the frying pan is higher than that in the start condition 2, the detected temperature of the thermistor is increased by 10 ° C., for example. At this time, the 1st setting threshold value of pan temperature determination shall be 4 degreeC, for example, and the 2nd setting threshold value shall be 9 degreeC, for example.

  In the case of the start condition 1, since the amount of change in the temperature detected by the thermistor is less than the first set threshold value, the left and right heating ports 2L and 2R are set to the set heating power at the start of heating after the pan temperature determination. The outputs of the inverter circuits 33L and 33R are controlled.

  In the case of the start condition 2, the change amount of the temperature detected by the thermistor is not less than the first set threshold value and less than the second set threshold value. In this case, if the set thermal power is less than the upper limit of 1 kW, the outputs of the inverter circuits 33L and 33R are controlled so that the left and right heating ports 2L and 2R become the set thermal power.

  In the case of start condition 3, the amount of change in the temperature detected by the thermistor is equal to or greater than the second set threshold. In this case, if the set thermal power is less than 500 W, the outputs of the inverter circuits 33L and 33R are controlled so that the left and right heating ports 2L and 2R become the set thermal power. If the set thermal power is 500 W or more, the left and right The outputs of the inverter circuits 33L and 33R are controlled so that the heating ports 2L and 2R become 500W. The control device 32 performs calculation of the amount of change in temperature and output control of the inverter circuits 33L and 33R according to the calculated amount of change.

  As described above, in the fourth embodiment, the amount of change in temperature is compared with the set threshold values (first, second, and third set threshold values) set according to the start conditions 1, 2, and 3. Therefore, it is possible to set the heating power more accurately than in the first to third embodiments. For this reason, the object to be heated is not heated too much, and the object to be heated can be prevented from being deteriorated by heat and ignition of oil in the object to be heated.

Embodiment 5 FIG.
In the second embodiment, it is described that an infrared sensor is used as the temperature sensor. However, since the infrared sensor generally cannot accurately detect a low temperature zone, the temperature detected by the infrared sensor is the first temperature when determining the pan temperature. You may make it start a heating, without performing pan temperature determination, when it is below setting temperature. In the third embodiment, it is described that the thermistor and the infrared sensor are used as the temperature sensor. However, as described above, when the temperature detected by the infrared sensor is equal to or lower than the predetermined value when the pan temperature is determined, the thermistor is detected. You may make it perform pan temperature determination only with temperature.

Embodiment 6 FIG.
In addition, in the mode where the heating process pattern such as frying pan preheating and fried food preheating is determined, if the pan temperature is judged to be high as a result of the pan temperature judgment, the heating power is lower than that at the normal temperature start. The integrated power of the heating process may be made lower than that of the normal heating process by performing heating or heating shorter than the time of the normal heating process (preheating time).

In the first to sixth embodiments, the output of the inverter circuits 33L and 33R is stopped when the pan temperature is determined. However, the present invention is not limited to this. For example, when determining the pot temperature, the outputs of the inverter circuits 33L and 33R are set so that the minimum heating power (for example, 100 w) required for cooking is lower or a lower heating power for a certain time (pan temperature detection time). Control.
Thus, since the pan on the left and right heating ports 2L, 2R is heated with the minimum heating power (for example, 100 w) or lower than that when the pan temperature is determined, the heating after the pan temperature determination is completed. Compared with Embodiments 1 to 6, the pan at the start can be heated in a short time.

  1 Induction heating cooker, 2C body case, 2L left heating port, 2LC left heating coil, 2R right heating port, 2RC right heating coil, 3 grill cooker, 11 main power switch, 12L left power adjustment dial, 12R Power adjustment dial on the right side, 13 Front operation unit, 14 Top plate, 15 Metal frame, 16 Center display panel, 17L Left display panel, 17R Right display panel, 18L Left display unit, 18R Right display unit, 19 Top operation , 20 Intake port, 21 Exhaust port, 22 Grill box, 23 Sauce pan, 24 Grill net, 25 Cooked food, 26 Grill door, 26A Handle, 27, Left heating port operation unit, 27a Fried food button, 27b Fry pan preheating Button, 27c On / Off button, 28 Operation unit for right heating port, 28a Deep-fried food button, 28b Ipan Preheat Button, 28c On / Off Button, 29 Grill Operation Unit, 29a Grill Menu Button, 29b Start / Stop Button, 29c Left Arrow Button, 29d Right Arrow Button, 29e Time Minus Button, 29f Time Plus Button, 31 Power Circuit 32 control device, 33L inverter circuit, 33R inverter circuit, 34 grill heater drive circuit, 34H sheath heater, 35 display drive circuit, 36 catalyst heater drive circuit, 37 sheath heater, 38 voice synthesizer, 39 speaker, 40 temperature detection circuit.

Claims (10)

A top plate on which an object to be heated is placed;
A heating coil disposed below the top plate;
An inverter circuit for converting direct current power to high frequency power, supplying a high frequency current to the heating coil to inductively heat the object to be heated;
A temperature sensor that detects the temperature of the object to be heated via the top plate;
A control device for controlling the output of the inverter circuit;
The control device reads the temperature of the top plate on which the object to be heated is placed from the temperature sensor for a certain period of time before the start of heating with the set thermal power, and calculates the amount of change in the temperature during the certain period of time. and, the induction heating cooker according to claim Rukoto control to heating is started the output of the inverter circuit in response to the amount of change in the start of heating after the predetermined time.   The said control apparatus controls the output of the said inverter circuit so that it may become the minimum thermal power required for heating cooking or a thermal power lower than it for the fixed time before the heating start by setting thermal power. Item 1. An induction heating cooker according to item 1.   The control device has a plurality of setting thresholds having different values, and controls the output of the inverter circuit based on a comparison result between the change amount and the plurality of setting thresholds. The induction heating cooker described.   The induction heating cooker according to any one of claims 1 to 3, wherein a thermistor is used for the temperature sensor.   The induction heating cooker according to any one of claims 1 to 3, wherein an infrared sensor is used as the temperature sensor. A thermistor and an infrared sensor are used for the temperature sensor,
The said control apparatus calculates the variation | change_quantity of the temperature in the said fixed time from each temperature of the said top plate and pan detected by the thermistor and the infrared sensor, The Claim 1 thru | or 3 characterized by the above-mentioned. Induction heating cooker.   When the temperature of the top plate detected by the infrared sensor is equal to or lower than a first set temperature, the control device shifts to the start of heating without calculating the amount of change in the temperature during the predetermined time. 6. The induction heating cooker according to claim 5, wherein   The controller calculates the amount of change using only the temperature of the top plate detected by the thermistor when the temperature of the top plate detected by an infrared sensor is equal to or lower than a first set temperature. The induction heating cooker according to claim 6.   The induction heating cooker according to any one of claims 1 to 8, wherein an upper limit value is set for the output of the inverter circuit controlled by the control device according to the amount of change.   When the preheating mode of the deep-fried food or the pan is selected, the control device controls the output of the inverter circuit according to the amount of change, and lowers the heating power in the preheating mode or shortens the preheating time. The induction heating cooker according to any one of claims 1 to 9.

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