JP2012114059A - Induction heating cooker - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible in an induction heating cooker to perform a preheating mode, which is suitable for frying etc., with a higher priority even when heating is started by other heating means while the preheating mode is used.SOLUTION: In an induction heating cooker, when a transition to a preheating mode occurs, heating is carried out at a predetermined heat output in a start-up mode, and when an amount of change in output of a temperature detection means 6 (an infrared sensor) from heating start becomes equal to or higher than a predetermined value, the heat output is reduced and a transition to a heat-retention mode for keeping temperature of a cooking container 7 occurs. A total power amount regulating means 21, when a total input current exceeds a limit value, selects one of induction heating parts 1a, 1b, 1c, or a heating means 10 to reduce its output, and thereby limits the total input current to the limit value or lower, and after the transition to the preheating mode, prohibits change in heat output of the induction heating part 1a or the induction heating part 1b which are in the start-up mode.

Description

  The present invention relates to an induction heating cooker used in a kitchen or restaurant of a general household.

  FIG. 8 shows a block diagram of an induction heating cooker that performs power control below the maximum current value of the device. First, when using the roaster heater 109, which is a heater device, when the user sets the roaster heater ON with the heating power setting means 117, the roaster heater control means 110 is turned on to start energization. Next, when the induction heating cooker A is used, the heating power setting means 117 sets the induction heating cooker A to ON, and further sets the desired heating power. At this time, the induction heating power calculation means 116 compares the value (so-called power consumption) obtained by multiplying the detection voltage of the power supply voltage detection means 113 and the detection current of the input current detection means 107a with the thermal power set by the user. Feedback control is performed on the drive frequency of the switching means of the inverter unit 106a so as to coincide with each other, so that the power consumption of the induction heating cooker A becomes constant. Moreover, when using the induction heating cooker B, similarly to the heating cooker A, control is performed.

  The total current calculating means 115 calculates the total current obtained by adding the calculated current of the roaster heater 109 (= the detected voltage of the power supply voltage detecting means 113 / the resistance value of the roaster heater 109) and the detected currents of the input current detecting means 107a and 107b. When the total sum of the total currents exceeds a predetermined current value Itotal, the drive frequency of the switching means of the inverter units 106a and 106b is changed, and feedback control is performed so that the total current becomes equal to or lower than the predetermined current value Itotal. . In this control, when the condition that the total current exceeds a predetermined current value Itotal is established, the control is performed in preference to the control for making the power consumption of the induction heating cookers A and B constant.

  With the above operation, the total current exceeds Itotal for a moment, and even when the power supply voltage fluctuates, the total current is always controlled to be equal to or lower than Itotal, so that the total current constantly exceeds Itotal. There is nothing. For this reason, it is possible to set a current value that is very close to the capacity of the breaker and the current rating of the power outlet. Thereby, since maximum power consumption can be made larger than before, the frequency of occurrence of thermal power limitation when a plurality of heaters are used simultaneously is reduced.

JP 2003-142247 A

  However, in the above-described conventional configuration, for example, in the case of a device having a control mode in which heating is continued with a predetermined heating power or more, for example, a device having a preheating mode for preheating the cooking container to an appropriate temperature, other heating If the heating power in the preheating mode is reduced to prevent the maximum current amount of the equipment from being exceeded when the heating of the means is started and the sum of the input currents exceeds the regulation value, the role of the function of the preheating mode is assumed. There was a problem that could not be fulfilled.

The present invention solves the above-mentioned problem. By controlling other heating means during the preheating mode, power control is performed with priority on the preheating mode even when the maximum current of the device is exceeded. Thus, it is possible to continue the preheating mode and to provide an easy-to-use induction heating cooker.

  In order to achieve the above object, an induction heating cooker of the present invention detects induction cooking means for induction heating a cooking container, a top plate provided above the induction heating means, and temperature of the cooking container. A temperature detecting means; an inverter for supplying a high frequency current to the induction heating means; an input current detecting means for detecting an input current; a total input power regulating means; a heating means comprising a resistor; and the cooking vessel Is equipped with a preheating mode that controls heating to a temperature suitable for starting cooking, and when the mode is shifted to the preheating mode, heating is performed with a predetermined heating output in the start-up mode, and the amount of change from the start of heating of the output of the infrared sensor is predetermined. When the above is reached, the heating output is reduced to shift to a heat retention mode for keeping the object to be heated, and when the total input current exceeds the regulation value, the total input power regulation means By selecting either the induction heating means or the heating means and reducing its output, the sum of input currents is suppressed to the regulation value or less, and the heating output of the induction heating means during the start-up mode This is a configuration that prohibits the change of.

  Thereby, even if there is an input of heating start of other heating means during the preheating mode in which the cooking container is heated until it reaches an appropriate temperature, the preheating mode is continued while controlling below the maximum current value of the device. It is possible to improve the usability.

  As described above, the present invention continues the preheating mode in which the cooking container is preheated to an appropriate temperature even when heating of other heating means is started during the preheating mode, and starts the fried food at the optimum temperature. I can do it.

External view of induction heating cooker in Embodiment 1 of the present invention The block diagram seen from the cross section of the induction heating cooking appliance in Embodiment 1 of this invention The circuit block diagram of the induction heating cooking appliance in Embodiment 1 of this invention The graph which shows the preheating mode of the induction heating cooking appliance in Embodiment 1 of this invention The circuit diagram of the infrared sensor of the induction heating cooking appliance in Embodiment 1 of this invention The figure which shows the output characteristic of the infrared sensor of the induction heating cooking appliance in Embodiment 1 of this invention The flowchart which shows operation | movement of the induction heating cooking appliance in Embodiment 1 of this invention. Block diagram of a conventional induction heating cooker

  The first invention is an induction heating means for induction heating of a cooking container, a top plate provided above the induction heating means, a temperature detection means for detecting the temperature of the cooking container, and a high frequency for the induction heating means. Inverter section for supplying current, input current detecting means for detecting input current, total input power regulating means, heating means composed of resistors, and heating the cooking container to a temperature suitable for starting cooking With a preheating mode to control, when transitioning to the preheating mode, heating is performed with a predetermined heating output in the start-up mode, and when the amount of change from the heating start of the output of the infrared sensor is equal to or greater than a predetermined value, the heating output is reduced, The overall input power regulation means moves to a heat insulation mode for keeping the object to be heated, and if the sum of the input currents exceeds a regulation value, either the induction heating means or the heating means The sum of the input currents is suppressed to be equal to or lower than the regulation value by lowering the output by selecting this, and the change in the heating output of the induction heating means during the start-up mode is prohibited. Therefore, even when the maximum current value of the device is likely to be exceeded, the heating of the induction heating means in the preheating mode is given priority to continue heating, so that the stir-fried food can be started at the optimum temperature. Can be improved.

  According to a second invention, in particular, in the first invention, the top plate is formed of a material that transmits infrared rays, and the temperature detecting means is constituted by an infrared sensor that detects infrared rays emitted from the bottom surface of the cooking vessel. This makes it possible to accurately detect the temperature, increase the heating power during the preheating mode as much as possible, and improve the usability of the preheating mode.

  In particular, in the first or second invention, the third invention is provided with transmission means for performing notification or display, and when the preheating mode is completed, the transmission means performs notification or display so that preheating is performed. It is possible to inform the user that the mode has ended and the other heating means is ready for use, and the usability can be improved.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the present invention is not limited to the embodiments.

(Embodiment 1)
FIG. 1 is an external view showing an induction heating cooker according to the first embodiment of the present invention.

  In FIG. 1, induction heating parts 1a, 1b, and 1c are formed by heating coils, and are arranged at a total of three locations on the right and left and the back as viewed from the front of the main body. The top plate 2 is an electrical insulator such as glass on which an object to be heated (not shown) is placed, has a high light transmittance, and the top surface operation unit 3 is disposed on the top plate 2. Yes, the kangaroo operation unit 4 is arranged on the front surface of the cooking device. The grill unit 5 is for grilling fish and chicken.

  FIG. 2 is a block diagram seen from a cross section of the induction heating cooker in the first embodiment of the present invention. In FIG. 2, the cooking container 7 is the induction heating unit 1 a, and the temperature detection means 6 is arranged at the center of the induction heating unit 1 a, and the infrared rays from the object to be heated are passed through the top plate 2. The temperature is detected from the amount of radiation. The inverter unit 12a will be described later.

  Moreover, FIG. 3 is a circuit block diagram which shows the structure of the induction heating cooking appliance in the 1st Embodiment of this invention. In FIG. 3, a commercial AC power supply 8 is provided, and a rectifier circuit 9 rectifies the commercial AC power supply and is constituted by a diode bridge. The heating means 10 forms the grill portion 5, and the heating control means 11 turns on / off the heating means 10. The heating control means 11 is generally constituted by a relay, a triac or the like, and is a relay in the present embodiment. The inverter units 12a, 12b, and 12c supply high-frequency current to the heating coils that constitute the induction heating units 1a, 1b, and 1c, and there are ones corresponding to the three induction heating units shown in FIG. Inverter unit 12a is supplied to the heating coil constituting left induction heating unit 1a, inverter unit 12b is supplied to right induction heating unit 1b, and inverter unit 12c is supplied to high frequency induction heating unit 1c. It has become.

  The power control of the inverter units 12a, 12b, and 12c is generally controlled by the ON time of the switching element, and the control is performed by the control circuit 14 including the microcomputer 13. In the control circuit 14, there are input current detection means 15 a, 15 b, 15 c for detecting an input current to each inverter unit, and a voltage detection means 16 for detecting a power supply voltage, which is detected by the voltage detection means 16. The output power is obtained from the product of the detected voltage and the current detected by the input current detection means 15a, 15b, 15c, and the switching elements are controlled by the power control means 17a, 17b, 17c so as to be in accordance with the setting of the thermal power. To do.

The total power amount regulating means 21 then detects the current detected by each input current detecting means, the power supply voltage detected by the voltage detecting means 16 when the heating means 10 forming the grill portion is on, and the heating means 10. Each inverter unit and the heating means 10 are controlled so that the total current of the device obtained from the current flowing through the heating means 10 calculated from the resistance value of the current does not exceed a predetermined current value. The predetermined current referred to here is, for example, a 25 A or 30 A current breaker (breaker) provided in a general household, and it is required to control the current to be equal to or less than the current value. Should be set below the current value.

  The operation means 18 is composed of four switches and the like in the present embodiment. First, the menu selection means 18a sets the cooking container so that the temperature is suitable for the heating mode in which heating is performed based on the thermal power setting, the preheating mode in preparation for the start of cooking when frying, which will be described later, and the fried food. Select the type of heating, such as fried food mode to control the temperature. The output adjusting means 18b and 18c are output adjusting means. For example, if the heating power is to be increased during heating in the heating mode described above, an instruction to increase the heating power can be given by inputting a signal to the output adjusting means 18c. On the other hand, if it is desired to reduce the heating power, a command to lower the heating power can be given by inputting a signal to the output adjusting means 18b. Further, when the heating start means 18d inputs a signal to the heating start means 18d in a state where the menu selection means 18a selects the heating menu, the heating start means 18d starts heating with the selected heating menu.

  Moreover, the display means 19 displays the menu currently selected by the menu selection means 18a, for example, and displays the menu of the heating state at that time, such as a fried food mode and a preheating mode.

  In addition, when the signal is input to the operation unit 18, the notification unit 20 notifies the reception of the signal with a signal sound, or guides by voice when an incorrect operation is performed. In addition, when the heating state reaches a certain condition in the fried food mode or the preheating mode, the user is notified of this.

  FIG. 4 is a graph showing a preheating mode in which the cooking container is preheated when frying or the like, which is a feature of this device.

  The graph of FIG. 4 describes the three of the temperature of the cooking container 7 that is the object to be heated, the temperature detected by the temperature detection means 6, and the output power of the induction heating unit, with the horizontal axis as the time axis. When heating is started in the preheating mode, heating is started at a predetermined output power while detecting the temperature. Here, the heating is continued with the electric energy of P1. At this time, if the electric power exceeding a predetermined value is not input, it takes a long time for preheating, or the temperature of the cooking container 7 does not rise to the temperature required for preheating. Disappear. Further, in order to accurately detect that the temperature has risen to a predetermined temperature (preheating has been completed), it is very important that the temperature change does not fluctuate greatly by continuously heating with a constant heating power. If heating is performed while the heating power is not constant but the heating power is fluctuating, it is necessary to have a very complicated program configuration for detecting completion of preheating. That is, it is no exaggeration to say that it is indispensable to continue heating at a constant heating power from the beginning of heating in order to realize the function of the preheating mode.

  The constant heating power is exactly the amount of power P1, which is 2000 W in this embodiment. And heating is continued, confirming the temperature detected by the temperature detection means 6, and the variation | change_quantity of the temperature at 2000 W or more. And when the output of a certain temperature detection means (here infrared sensor) 6 reaches predetermined value V1, it will be judged that preheating was completed and heating will be continued by the thermal power required in order to maintain the temperature after that. In the present embodiment, the timing of t1 in FIG. 4 is the timing when it is determined that the preheating is completed. Then, at the timing of t1, the notification means 20 in FIG. 3 notifies that the preheating has been completed with an electronic sound. Thereafter, temperature control is performed at a low watt which is sufficient to maintain the temperature, not a constant heating power.

  FIG. 5 shows a circuit diagram of an infrared sensor that constitutes the temperature detecting means 6 of the present embodiment. The infrared sensor includes a photodiode 61, an operational amplifier 62, and resistors 63 and 64. One ends of the resistors 63 and 64 are connected to the photodiode 61, and the other ends are connected to the output terminal and the inverting output terminal of the operational amplifier 62, respectively. The photodiode 61 is a light receiving element formed of silicon or the like through which a current flows when irradiated with infrared light having a wavelength of about 3 microns or less that passes through the top plate 2. The current generated by the photodiode 61 is amplified by the operational amplifier 62 and output to the microcomputer 13 that is a part of the control circuit 14 as an infrared signal output 65 (corresponding to the voltage value V) indicating the temperature of the cooking vessel 7. Since the infrared sensor receives infrared rays radiated from the cooking container 7, the infrared sensor has better thermal response than a thermistor that detects the temperature via the top plate 2.

  FIG. 6 shows the output characteristics of the infrared sensor. In FIG. 6, the horizontal axis represents the bottom surface temperature of the cooking vessel 7, and the vertical axis represents the voltage value of the infrared signal output 65 output from the infrared sensor. The infrared signal output 65 has output characteristics 65a to 65c based on the influence of ambient light. The output characteristic 65a shows the infrared signal output 65 when no disturbance light is contained, that is, when only infrared rays emitted from the cooking container 7 are received. The output characteristic 65b shows the infrared signal output 65 when weak disturbance light is incident on the infrared sensor. The output characteristic 65c indicates the infrared signal output 65 when strong disturbance light such as sunlight is included, for example.

  In the present embodiment, since the purpose is to perform preheating when a high thermal power such as a stir-fried food is required, the target temperature during preheating is high (for example, 280 ° C.). Therefore, it is only necessary to obtain an output at a high temperature. Therefore, the infrared sensor of the present embodiment outputs an infrared signal output 65 when the bottom surface temperature of the cooking vessel 7 is about 250 ° C. or higher, as shown by an output characteristic 65a, and an infrared signal when the temperature is lower than about 250 ° C. The output 65 is not output. In this case, “not outputting the infrared signal output 65” not only does not output the infrared signal output 65 at all, but also does not substantially output, that is, the microcomputer 13 is based on a change in the size of the infrared signal output 65. This includes outputting a weak signal that cannot substantially read the temperature change of the bottom surface of the cooking container 7. The output value of the infrared signal output 65 increases exponentially when the temperature of the cooking vessel 7 reaches about 250 ° C. or higher.

  When weak disturbance light is incident on the infrared sensor, a signal having a small value due to the disturbance light is output even when the temperature is less than about 250 ° C., as indicated by the output characteristic 65b. In addition, when strong disturbance light such as sunlight is contained, a large value signal is output even when the temperature is less than about 250 ° C. as in the output characteristic 65c.

  Thus, the infrared signal output 65 output from the infrared sensor is affected by ambient light. Therefore, in the present embodiment, completion of preheating, that is, whether or not the cooking container 7 has reached the target temperature is determined by whether the output increase amount ΔV of the voltage value V of the infrared signal output 65 from when the preheating is started is predetermined. Judgment is made based on whether or not the increase is exceeded. As a result, the output of the infrared sensor changes abruptly in the target temperature range even in the presence of ambient light, so that there is little variation in temperature detection.

  FIG. 7 is a flowchart showing an operation when a command for operating the heating unit 10 is issued in a state where the left and right induction heating units 1a, 1b, and 1c are operating.

  Since the maximum heating power of the rear induction heating unit 1c is as small as 750 W, the preheating mode operates in the left and right induction heating units 1a and 1b.

First, it is assumed that all of the left and right induction heating units 1a, 1b, and 1c are operating. Here, it is assumed that there is an instruction to start heating of the heating means 10 which is a grill portion for grilling fish or the like in step S1. Then, first, in step S2, it is confirmed whether the left induction heating unit 1a is being heated in the preheating mode. If heating is being performed in the preheating mode, a power of at least 2000 W is required in the preheating mode. Or you need to stop the preheating mode and lower the watt of the left fired burner. Here, since the preheating mode is preferentially controlled, the process proceeds to step S4 and the heating start command of the heating means is invalidated. On the other hand, if the left induction heating unit is not in the preheating mode in step S2, the process proceeds to step S3.

  In step S3, as in step S2, it is checked whether the right induction heating unit 1b is currently heating in the preheating mode. Similarly, if the right induction heating unit 1b is in the preheating mode, the process proceeds to step S4, and the heating start command of the heating means 10 is invalidated. If not in the preheating mode, the process proceeds to step S5.

  In step S5, since there is no induction heating unit operating in the preheating mode, each induction is performed so that the total electric energy of the device is equal to or less than a predetermined value (5600 W in the present embodiment) when receiving the heating of the heating means. The maximum heating power that can be output from the heating unit is determined, and when heating is performed with more heating power, the watt is reduced to the maximum heating power. In the present embodiment, the maximum heating power is set to 1400 W for the left and right induction heating sections, and the maximum heating power is set to 750 W for the rear induction heating sections. Then, in step S6, the start of heating of the heating means that is the grill portion is received, and heating is started at 1900W. The total amount of power at this time is 1400 + 1400 + 750 + 1900 = 5450 W, and is in a state of being controlled to a predetermined value of 5600 W or less.

  As described above, in the present embodiment, there is a command to start heating of other heating means in an apparatus having a preheating mode that automatically performs preheating that is very convenient and important for skillfully performing frying. However, the preheating mode can be prioritized and the usability can be improved.

  The temperature detecting means 6 is composed of a sensor for detecting infrared rays. However, the temperature detecting means 6 is not limited to this, and may be a temperature sensitive element such as a thermistor. However, an infrared sensor having high temperature followability is more desirable. Needless to say.

  In addition, the state of each induction heating unit is not limited to the example shown in FIG. 5, and the input of other induction heating units is set so that the heating power of the induction heating unit during the preheating mode does not decrease below a predetermined output power. Needless to say, it is the gist of the present invention to have a configuration that does not restrict heating or accept heating.

  Moreover, although it was set as the structure which controls a power control means with one microcomputer 13 in FIG. 3, it is not restricted to this, For example, the total electric current amount is managed and the maximum electric power of each induction heating part or heating is controlled. Needless to say, the same effect can be obtained even if the configuration is such that each induction heating unit is controlled by having a microcomputer for each induction heating unit.

  Further, in the present embodiment, in step S5 in FIG. 5, the setting of the maximum heating power is 1400 W on the left and right and 750 W on the rear, but this is not limited to this, and even if the maximum heating power is limited, the heating is appropriate. There is no problem as long as the amount of electric power can be cooked, and if the total electric energy is within the range that does not lead to the operation of a current breaker that limits the maximum current normally installed in ordinary households. Needless to say, it's fine.

The induction heating cooker of the present invention has a preheating mode, and controls the total current amount of the device so that its function is prioritized. Therefore, the induction heating cooker and the multi-mouth type having a halogen cooker are included. It can be used for applications such as cooking appliances.

1a, 1b, 1c Induction heating unit (induction heating means)
DESCRIPTION OF SYMBOLS 2 Top plate 3 Top surface operation part 4 Kangaroo operation part 5 Grill part 6 Temperature detection means 7 Cooking container 8 Commercial alternating current power supply 9 Rectifier circuit 10 Heating means 11 Heating control means 12a, 12b, 12c Inverter part 13 Microcomputer 14 Control circuit 15a, 15b, 15c Input current detection means 16 Voltage detection means 17a, 17b, 17c Power control means 18 Operation means 18a Menu selection means 18b, 18c Output adjustment means 18d Heating start means 19 Display means (transmission means)
20 Notification means (transmission means)
21 Total Electricity Limiting Means 61 Photodiode 62 Operational Amplifier 63, 64 Resistor 65 Infrared Signal Output

Claims (3)

Induction heating means for induction heating the cooking container, a top plate provided above the induction heating means, temperature detection means for detecting the temperature of the cooking container, and an inverter unit for supplying a high frequency current to the induction heating means And an input current detecting means for detecting the input current, a comprehensive input power regulating means, a heating means constituted by a resistor, and a preheating mode for controlling the heating of the cooking container to a temperature suitable for starting cooking. When the preheat mode is entered, heating is performed with a predetermined heating output in the start-up mode, and when the amount of change from the start of heating of the output of the infrared sensor exceeds a predetermined value, the heating output is reduced to keep the object to be heated. While shifting to the heat retention mode,
When the total sum of input currents exceeds a regulation value, the total input power regulation means selects either the induction heating means or the heating means and reduces the output thereof, thereby reducing the total input current to the regulation value. An induction heating cooker configured to be suppressed below and to prevent a change in the heating output of the induction heating means during the start-up mode. The induction heating cooker according to claim 1, wherein the top plate is formed of a material that transmits infrared rays, and the temperature detection means is configured by an infrared sensor that detects infrared rays emitted from the bottom surface of the cooking container. The induction heating cooker according to claim 1 or 2, further comprising a transmission unit that performs notification or display, and configured to perform notification or display by the transmission unit when the preheating mode ends.