JPH11329699A - Induction heater cooker - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an induction heater cooker capable of safely stopping heating, if a temperature detecting element for a pot goes wrong. SOLUTION: This induction heater cooker has an inverter circuit part 3 for rectifying an alternating power source 1 and supplying high-frequency power to a heating coil 4, a control circuit part 7 for controlling heating output, a first temperature detecting element 9 on an under surface of a top plate 8 and above the heating coil 4, and a second temperature detecting element 11 on an upper part of the heating coil 4, and heating is stopped at the point of time when a detected temperature by the second temperature detecting element 11 exceeds a set temperature.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an induction heating cooker used in a commercial kitchen or the like.

[0002]

2. Description of the Related Art FIG. 3 is a block diagram of a conventional induction heating cooker. 1 is an AC power supply, 2 is a rectifier circuit for rectifying the AC power supply 1, 4 is a heating coil, 3 is an inverter circuit section for supplying a high-frequency current to the heating coil 4, 5 is an input current detection circuit, and 6 is AC. A power supply voltage detection circuit for detecting the voltage of the power supply supplied from the power supply 1;
And a control unit for controlling the conduction of the inverter circuit unit 3 with the power set by the input from the power supply voltage detection circuit 6.
Reference numeral 8 denotes a top plate on which a pot 10 serving as a load is placed. Reference numeral 9 denotes a temperature detecting element which is located above the heating coil and is located on the lower surface of the top plate 8 and measures the temperature of the lower surface of the top plate 8. Conveyed to.

In the conventional induction heating cooker, when the temperature of the pot rises, a temperature detecting element 9 placed on the lower surface of the top plate 8 detects the temperature, and a control unit 7 inputs a temperature detection output. When the temperature reaches the set temperature T1, the output is decreased, and when the temperature is equal to or lower than the set temperature T2, the output is increased. The inverter circuit unit 3 is controlled so that the temperature of the pan does not become excessively high and the pot is not in an abnormal state. .

[0004]

In the above conventional method,
The following problems are mentioned.

If the temperature detecting element breaks down, the temperature of the pot (load) cannot be controlled, and if a thermistor is used as the temperature detecting element, a short circuit or disconnection can be detected. If a failure occurs in a state with a value, it cannot be detected, and if it has been burnt, it cannot be detected even in a very high temperature state, and its reliability is poor. there were.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above-mentioned problem, and has been made in order to detect the temperature of the lower surface of the top plate, which is located on the lower surface of the top plate and above the heating coil. A first temperature detecting element and a second temperature detecting element for detecting a temperature above the heating coil, and when the temperature of the first temperature detecting element reaches an arbitrary temperature, the driving frequency is changed and the output is gradually changed. The output is stopped when the temperature of the second temperature detecting element reaches a temperature higher than the set temperature.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, a first temperature detecting element for detecting a temperature of a lower surface of a top plate performs a normal temperature control, and a second temperature detecting element for detecting a temperature above a heating coil is abnormal. When the first temperature detecting element fails, the power supply is stopped so that the temperature of the pot does not rise abnormally and a fire does not occur, thereby improving safety. Is achieved.

[0008]

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view showing the structure of an induction heating cooker according to an embodiment of the present invention. The pot 10 to be heated is placed on the top plate 8 at the top of the main body 15. The heating coil 4 is provided below the top plate 8, the first temperature detecting element 9 is provided above the heating coil 4 and below the top plate 8, and the second temperature detecting element 11 is provided at the center of the heating coil 4. Below the heating coil 4, an inverter circuit unit 3 and a control unit 7 for supplying a high-frequency current to the heating coil 4
Is provided, and an operation panel unit 14 for operating the induction heating cooker is provided on the front of the product. Inverter unit 12
A cooling fan 13 is provided in front of the product, and the air taken in through an intake hole in front of the product is exhausted to an exhaust hole at the rear of the product to forcibly cool the heating coil 4 and the inverter circuit unit 3.

FIG. 2 is a block diagram of the induction heating cooker.

1 is an AC power supply, 2 is a rectifier circuit for rectifying the AC power supply 1, 4 is a heating coil, 3 is an inverter circuit for supplying a high-frequency current to the heating coil 4, 5 is an input current detection circuit, 6 Is a power supply voltage detection circuit for detecting the voltage of the power supply supplied from the AC power supply 1, and 7 is a power supply control circuit for controlling the power supply to the inverter circuit section 3 with the power set by the input from the input current detection circuit 5 and the power supply voltage detection circuit 6. 8 is a top plate on which a pot 10 serving as a load is placed;
Is a first temperature detecting element which is located above the heating coil and is located on the lower surface of the top plate 8 and measures the temperature of the lower surface of the top plate 8; 11 is located below the top plate 8 and located above the heating coil 4 In a certain second temperature detecting element,
Outputs of these temperature detecting elements are transmitted to the control unit 7, respectively.

In the above configuration, when the pot 10 is placed on the top plate 8 and heating is started, the pot 10 is heated and the temperature detected by the first temperature detecting element 9 for detecting the temperature of the pot via the top plate 8 is reduced. Rise. First temperature detecting element 9
Is a thermosensitive element such as a thermistor. As the second temperature detecting element 11, a thermosensitive element such as a thermistor or a thermostat is used. When the temperature of the pot rises and the temperature detected by the first temperature detecting element 9 reaches the set temperature T1, the control unit 7 reduces the heating output, and stops heating when the temperature reaches the set temperature T2 higher than T1. . And the temperature of the pot drops and T
When the temperature falls below the set temperature of T3 set to a temperature lower than 1, power is supplied again with an arbitrary heating output. Here, when heating is performed in a state where the first temperature detecting element 9 has failed and cannot be controlled, the temperature of the pan becomes extremely high when the contents of the pan 10 are empty. In such a case, the temperature of the heating coil 4 becomes very high, the temperature of the second temperature detecting element placed above the heating coil 4 becomes high, and the heating is stopped at once when the detected temperature becomes T4 or more. Let it. When the heating is stopped by the second temperature detecting element 11, an abnormality is notified by a display LED or the like arranged on the operation panel, and the user is notified of the abnormal state.

[0013] By doing so, it is possible to perform safe heating without raising the temperature of the pan above a certain set temperature.

[0014]

As described above, according to the present invention, the heating of the temperature of the pan can be normally controlled by the first temperature detecting element, and when the first temperature detecting element fails, the heating coil can be controlled. The heating can be safely stopped by the second temperature detecting element placed at the position.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of an induction heating cooker showing one embodiment of the present invention.

FIG. 2 is a block diagram.

FIG. 3 is a block diagram of a conventional induction heating cooker.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 AC power supply 2 Rectifier circuit 3 Inverter circuit part 4 Heating coil 5 Input current detection circuit 6 Power supply voltage detection circuit 7 Control part 9 1st temperature detection element 11 2nd temperature detection element

Claims (1)

[Claims] A rectifier circuit for converting an AC power supply to a DC power;
This DC power supply is supplied to a resonance circuit including a heating coil and a capacitor, and an inverter circuit that generates a high-frequency resonance current in the resonance circuit by the switching element, and changes the drive frequency of the switching element according to the input power to change the output power. Consisting of a control circuit that can
An induction heating cooker for heating by an eddy current loss generated in an object to be heated placed on a heating coil by a high-frequency magnetic field generated in the heating coil, wherein the heating coil (4)
A first temperature detecting element (9) positioned above the heating coil (4) for detecting the temperature of the pan, and a second temperature detecting element (11) for detecting the temperature above the heating coil (4). When the temperature of the first temperature detecting element (9) reaches an arbitrary temperature, the driving frequency is changed to gradually lower the output, and the second
When the temperature detecting element (11) reaches a detection temperature set to a temperature higher than that of the first temperature detecting element (9),
An induction heating cooker having means for stopping output.