JP2003086343A - Electromagnetic cooker - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electromagnetic cooker surely detecting abnormal overheating. SOLUTION: The electromagnetic cooker comprises induction heating coils 7, 8 under a top plate 2 on which, a cooking vessel 37 is placed, a temperature sensor 36 arranged at almost the central part of the heating coils, an inverter circuit 30 supplying electric power to the induction heating coils by frequency control, input power monitoring circuits 34, 35 detecting the input power supplied to the induction heating coils, and a control circuit 32 controlling the inverter circuit and the like depending on the output of the input power monitor circuits, the output of the temperature sensor, or the like. The control circuit is constructed so as to judge whether the cooking vessel is abnormally heated or not, depending on the driving frequency of the inverter circuit and input power.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electromagnetic cooker that heats and cooks by induction heating.

[0002]

2. Description of the Related Art In a general electromagnetic cooker, an induction heating coil is arranged under a top plate mounted on the top surface of an appliance body, and a temperature sensor is arranged at a substantially central position of the induction heating coil. By detecting the temperature of the cooking container placed on the top plate by the temperature sensor and controlling the electric power supplied to the induction heating coil based on the detection result, the cooking object stored in the cooking container Is configured to be heated to a set temperature or to detect abnormal heating of the cooking container.

On the other hand, there are many kinds of cooking containers suitable for the electromagnetic cooker, generally, there are an iron-based pot and a SUS-based pot, but the SUS-based pot has poor heat conductivity. Things
Some pan bottoms warp inward, and if this pan bottom warps, the temperature difference between the temperature detected by the temperature sensor and the temperature of the pan becomes large, especially in high-temperature cooking such as stir-fry cooking and fried cooking, especially in small amounts. Even if the cooking container is abnormally heated at the time of cooking, there is a problem that this cannot be quickly detected by the temperature sensor.

[0004]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to reliably detect an abnormal temperature rise in the cooking container and prevent abnormal overheating even if the bottom surface of the cooking container is warped.

[0005]

According to the present invention, there is provided a top plate on which a cooking container is placed, an induction heating coil mounted below the top plate, and a temperature sensor arranged at a substantially central position of the heating coil. And an inverter circuit that supplies electric power to the induction heating coil by frequency control, an input power monitor circuit that detects the input power supplied to the induction heating coil, and the output of this input power monitor circuit, the output of the temperature sensor, etc. And a control circuit for controlling the inverter circuit and the like, the control circuit is configured to determine whether or not the cooking container is abnormally overheated by the drive frequency of the inverter circuit and the input power. It is a thing.

Further, according to the present invention, the control circuit lowers the output of the inverter circuit to a preset output and notifies it when it is determined that the cooking container is abnormally overheated by the drive frequency of the inverter circuit and the input power. It is composed of components.

Further, according to the present invention, the control circuit is configured to stop the heating operation and notify when the cooking container is judged to be abnormally overheated.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION First, an embodiment of the present invention will be described with reference to FIG. 1. Reference numeral 1 is an electromagnetic cooker body used by being incorporated in a system kitchen or the like by a drop-in method, and a top plate made of heat-resistant glass on the upper surface. 2 is attached, and an intake / exhaust cover 4 having a large number of vent holes 3 ... Is detachably attached to the rear of the top plate.

An operation panel 5 is mounted on the right side of the front surface of the main body 1 of the electromagnetic cooker, and a door 6 for a roaster is arranged on the left side of the operation panel so as to be freely drawn out.

Further, below the top plate 2, induction heating coils 7 and 8 are arranged on the left and right sides in the front, and a gradient heater 9 is built in between the heating coils.

On the other hand, as shown in FIG. 2, the operation panel 5 is mainly divided into three sections in the left-right direction, the left and right seesaw type power switch 10 is set on the right side, and fried food cooking is set under this power switch. Fried food key 11 and operation key 1 below which turns on / off the power supply to the induction heating coil 8 on the right side.
2 and a pair of heat power setting keys 13 and 13 for raising or lowering the set heat power are arranged, and the fried food key 11 and the operation key 12 and the heat power setting keys 13 and 13 are used for the induction heating coil 8 that constitutes the right stove. It is configured to set the operation.

A roaster operation key 14 and a heat power setting key 15 are arranged on the upper side in the center of the operation panel 5, and an operation key for turning on / off the energization of the radiant heater 9 is provided under them. A pair of heat power setting keys 17 and 17 are arranged in the same manner as 16, and three heat power display lamps 18 for roasters are provided on the heat power setting key 15 for the roaster.
.. is placed and every time the heat setting key 15 is turned on,
The roaster's heating power is set to be sequentially switched from weak-medium-strong-weak to a loop.

Further, on the left side of the operation panel 5,
A timer key 19 is arranged, and a pair of heating power setting keys 21 and 21 are arranged below the timer key 19 as well as an operation key 20 for turning on / off the energization of the induction heating coil 7 on the left side. Four timer display lamps 22 ... Are arranged on the upper side, and each time the timer key 19 is turned on, 0.5 (hours) -1-2-3-off-0.
5 and the loop-shaped switching are sequentially set, and the operation of the induction heating coil 7 forming the left stove is set by these.

The operation keys 12, 14, 16, 2 described above are used.
At 0, operation lamps 23, 24, 25, and 26 formed of LED lamps and the like are arranged adjacent to them, and a fried food lamp 27 is arranged adjacent to the fried food key 11.

Further, in the above embodiment, the fried food key 11 is arranged only on the operating portion for the right stove, and the timer key 19 is arranged only on the operating portion for the left cooking stove. Is set only for the left stove, but the present invention is not limited to this, and these functions may be added to both the left and right stoves and the gradient heater 9.

FIG. 3 shows a part of a circuit block diagram for controlling the energization of the induction heating coils 7, 8 and the like. A DC conversion circuit 29 is connected to a commercial 200V power source 28 via the power switch 10. At the same time, the inverter circuit 30 is connected to the output of the DC conversion circuit, and the induction heating coil 8 on the right side is provided at the output of the inverter circuit, and the coil current detection means 31 for detecting the current value supplied to the coil. The series circuit of is connected.

A control circuit 32 is mainly composed of a microcomputer, and the inverter circuit 30 is provided at an output port.
And a notification buzzer 33 are connected, the operation panel 5 is connected to the input / output port, and the input port is
The output of the input current detection means 34 connected between the power source 28 and the DC conversion circuit 29, the output of the input voltage detection means 35 connected to the output of the DC conversion circuit 29, and the substantially central portion of the induction heating coil 8. A temperature sensor 36 such as a thermistor arranged in the above is connected.

Further, the temperature sensor 36 is configured to detect the temperature of the cooking container 37 placed on the top plate 2 via the top plate 2.

Incidentally, the input power is calculated from the outputs of the input current detection means 34 and the input voltage detection means 35, and these constitute an input power monitor circuit.

On the other hand, the inverter circuit 30 adjusts the electric power supplied to the induction heating coil 8 by frequency control. In this case, as shown by A and B in FIG. If the frequency is lowered by controlling the on / off time of a switching element (not shown), the induction heating coil 8 is energized for a longer time to increase the output, and if the frequency is increased, the output is decreased.

FIG. 5 shows frequency characteristics when the output of the induction heating coil is adjusted by the above frequency control and heating is performed using an iron-based cooking container.
The solid line shows the characteristics when normal, and the broken line shows the characteristics when the cooking container abnormally overheats.

As described above, when the cooking container is abnormally overheated to 200 ° C. or more due to empty heating or the like, the cooking container 3
7 increases to increase the resonance frequency f of the inverter circuit 30.
₀ decreases.

Therefore, the present invention detects abnormal overheating of the cooking container during high temperature cooking such as stir-fried food cooking and fried food cooking by utilizing the above characteristics, and the operation of the present invention will be described with reference to the flowchart of FIG. Then, at S1, run key 1
When 2, 2 are turned on, the operation lamps 23, 26 are activated in S2.
Is turned on and high-frequency heating is started.

Next, in S3, it is determined whether or not the output of the inverter circuit 30 has reached the thermal power set by the thermal power setting keys 13, 13, 21, 21, and when the output reaches the S4, the inverter circuit 30 at that time is determined. The driving frequency, the input power calculated from the outputs of the input current detection means 34 and the input voltage detection means 35, and the initial heating state such as the set thermal power are stored in a memory built in or attached to the control circuit 32.

Thereafter, the process proceeds to S5, and the stored initial heating state is compared with the current driving frequency and input power to determine whether the cooking container 37 is abnormally overheated. If it is determined that the cooking container 37 is abnormally overheated, the process proceeds to S6. Then, the output of the inverter circuit 30 is reduced to a predetermined thermal power, and then the process proceeds to S7, where it is determined whether the temperature detected by the temperature sensor 36 is equal to or higher than a preset predetermined temperature (for example, 200 ° C.). To stop heating.

On the other hand, when the detected temperature is lower than the predetermined temperature in S7, the process proceeds to S9 to continue the heating with the lowered thermal power,
When the heating is stopped in S8, the process proceeds to S10, in which it is determined again whether or not the temperature detected by the temperature sensor 36 is lower than the predetermined temperature. In this case, the process returns to S5 and the above operation is repeated.

With these configurations, the bottom of the cooking container 37 warps inward, and the temperature of the cooking container 37 cannot be accurately detected by the temperature sensor 36, or the temperature of the cooking container 37 depends on the material of the cooking container 37. Even when it is not possible to detect rapidly, the abnormal heating of the cooking container 37 can be detected promptly from the drive frequency of the inverter circuit 30 and the input power.

FIG. 7 is a flow chart showing another embodiment of the present invention. Explaining only the differences from the flow chart of FIG. 6, the initial heating state stored in S5, the current drive frequency and the input power are shown. By comparison, it is determined whether or not the cooking container is abnormally overheated. When it is determined that the cooking container is abnormally overheated, the process proceeds to S6, the output of the inverter circuit 30 is reduced to a predetermined heating power, and the buzzer 33 is operated to notify the abnormal overheat It is configured like.

Thus, when abnormal overheating of the cooking container 37 occurs, a notification can be given to notify the occurrence of the abnormality, and the notification can alert the user and prevent ignition or the like. is there.

FIG. 8 is a flow chart showing still another embodiment of the present invention. Explaining only the differences from the flow chart of FIG. 6, the initial heating state stored in S5, the current drive frequency and the input power are shown. Is compared to determine whether the cooking container 37 is abnormally overheated.
After proceeding to step 1 and stopping heating for a preset time (for example, 20 seconds), it proceeds to step S12, and it is determined whether or not a predetermined time (for example, 10 seconds) has elapsed since heating was started. Then, it is determined whether or not the current heating state is the same as the initial state stored in S4. If they are the same, the process proceeds to S7.

On the other hand, if it is not the same as the initial state in S13, it is judged that the abnormal state continues and the process returns to S11 to stop the heating.

With these configurations, when the cooking container 37 is abnormally overheated, the heating is stopped, and it is possible to prevent the ignition due to the abnormal overheating and the kogation of the food to be cooked.

[0033]

According to the configuration of the present invention, by detecting abnormal overheating of the cooking container from the drive frequency of the inverter circuit and the input power, the bottom of the cooking container warps inward and the temperature of the container is detected by the temperature sensor. Even if it cannot be accurately detected, the abnormal temperature rise of the cooking container can be detected quickly and reliably.

Further, according to the structure of the present invention, when abnormal heating of the cooking container is detected, the output of the inverter circuit is lowered and the alarm is given so that the cooking can be continued while notifying the danger. It is possible to cook while preventing as much as possible and improve usability.

Further, according to the configuration of the present invention, when abnormal overheating of the cooking container is detected, the heating operation is stopped and the alarm is issued to surely prevent ignition due to abnormal overheating.

[Brief description of drawings]

FIG. 1 is a perspective view showing an embodiment according to the present invention.

FIG. 2 is a plan view of the same.

FIG. 3 is a block diagram showing an embodiment of a control circuit of the same.

FIG. 4 is a time chart of the same inverter circuit.

FIG. 5 is an operating characteristic diagram of the same inverter circuit.

FIG. 6 is a flowchart for similarly explaining the operation.

FIG. 7 is a flowchart showing another embodiment of the present invention.

FIG. 8 is a flowchart showing another embodiment of the present invention.

[Explanation of symbols]

2 Top plate 7 induction heating coil 8 induction heating coil 30 inverter circuit 32 control circuit 34 Input current detection means 35 Input voltage detection means

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Toshiya Nishimoto             3-201 Minamiyoshikata, Tottori City, Tottori Prefecture Tottori             Sanyo Electric Co., Ltd. (72) Inventor Masami Akemi             3-201 Minamiyoshikata, Tottori City, Tottori Prefecture Tottori             Sanyo Electric Co., Ltd. (72) Inventor Takuo Ohara             3-201 Minamiyoshikata, Tottori City, Tottori Prefecture Tottori             Sanyo Electric Co., Ltd. F term (reference) 3K051 AA01 AB06 AB14 AC09 AC12

Claims (3)

[Claims] 1. A top plate on which a cooking container is placed, an induction heating coil mounted below the top plate, a temperature sensor arranged at a substantially central position of the heating coil, and a frequency to the induction heating coil. An inverter circuit that supplies power by control, an input power monitor circuit that detects the input power supplied to the induction heating coil, and the inverter circuit based on the output of the input power monitor circuit, the output of the temperature sensor, and the like. A control circuit for controlling the above, etc., characterized in that the control circuit is configured to determine whether or not the cooking container is abnormally overheated by the drive frequency of the inverter circuit and the input power. Induction cooker to do. 2. The control circuit reduces the output of the inverter circuit to a preset output and informs it when it is determined that the cooking container is abnormally overheated by the drive frequency of the inverter circuit and the input power. The electromagnetic cooker according to claim 1, wherein the electromagnetic cooker is configured as described above. 3. The electromagnetic cooker according to claim 1, wherein the control circuit is configured to stop the heating operation and notify when the cooking container is judged to be abnormally overheated.