JPH02207483A - Induction heating cooker - Google Patents

Abstract

PURPOSE:To restrain inflammation of cooking oil at the time of preparing tenpura by providing an induction heating cooker with a control section controlling alternating field generated by a heating coil, the first temperature detecting means located underneath a resting plate, and the second temperature detecting means which is detachably fitted onto a cooker main body, and the temperature detecting section of which can be inputted into a pan while the pan is being heated up. CONSTITUTION:When the resistance value of No.2 temperature detecting element 13 of a temperature probe P is changed with the temperature of cooking oil in a pan 12 increased, and when the negative input of a comparator COMP2 is resultantly consistent with the positive input of it, the output of the COMP2 goes to the 'L' level so that a control circuit 15 prohibits heating action. When the cooking oil is decreased in temperature, the output of the COMP2 goes to the 'H' level again, starting heating action. On the other hand, when an operator forgets to plug the probe P into a jack or when the probe is insufficiently plugged in, the COMP2 is switched over to No.1 temperature detecting element 11, the temperature of the pan 12 is thereby controlled not to exceed one set by a temperature setting means VR.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to an induction heating cooker having a temperature detection means for directly detecting the temperature of an object to be heated.

(b) Conventional technology An induction heating cooker heats a cooking pot by induction using a high-frequency alternating magnetic field. Among such induction heating cookers, one that directly detects the temperature of the food in the pot with a probe or the like and uses it for heating control is disclosed in, for example, Japanese Patent Laid-Open No. 59-149684.
It is indicated by the number.

(c) Problems to be Solved by the Invention However, in such an induction heating cooker, there is no problem as long as the temperature probe, which is the temperature detection means, appropriately detects the temperature of the food to be heated in the pot. If the food protrudes from the pot, there is a risk that the detected temperature will remain low and the food may become abnormally heated.

(d) Means for Solving the Problems The present invention has been made in view of the above points, and includes a control section that controls the generation of alternating magnetic flux from the heating coil, and a control section directly below the mounting plate. A first temperature detection means provided therein; and a second temperature detection means detachably provided in the cooking device main body, the temperature detection part of which can be inserted into a pot being heated. The control section controls the heating of the pot based on signals from the first and second temperature detection means.

(e) Effect Even if the second temperature detection means cannot detect the temperature, the first temperature detection means prevents abnormal heating.

(f) Example Fig. 1 is a circuit block diagram of the induction heating cooker of the present invention, (1) is a power switch for turning on and off the alternating current power (AC), (2) is a current fuse, (3) is a step-down transformer for supplying power to the control circuit (15) that controls the operation of this cooker, (4) is a cooling fan motor for cooling internal electrical components, (5) is a rectifier bridge, (6
) is a choke coil that forms a filter together with the capacitor (7), which prevents high frequencies from leaking into the power line.
(8) is an induction heating coil; (9) is a semiconductor switching element connected in series to this induction heating coil (8), which is controlled on and off by a signal from a control circuit (15); generates high-frequency current.

Note that a one-chip Darlington transistor is normally used as the semiconductor switching element, and a damper diode is also built in. (10) represents the switching element (
9) is a resonant capacitor that resonates with the induction heating coil (8) and allows current to flow continuously through the induction heating coil (8). (Ill is the top plate for the pot device (S
+The first temperature sensing element is placed in pressure contact with the back surface, and usually a thermistor is used. (12) is a cooking pot, (13)
is a second temperature detection element (temperature probe) for directly detecting the temperature of the food to be cooked inside the cooking pot (12), especially the oil during tempura cooking, and a thermistor is usually used for this as well. . (14) is a current sensor that detects alternating current for input control, and a current transformer is usually used. Further, the above-mentioned control circuit (15) generates a signal for controlling the semiconductor switching element (9) on and off in order to cause a continuous high-frequency current to flow through the induction heating coil. (1
6) is the temperature control circuit, and the mode changeover switch (17)
In normal "heating" mode, the first temperature sensing element (1
11 detects the temperature of the pot from 160° to 200°C and 240°C
It is set and activated to detect abnormal temperature rise of the pot in °C.
In "temperature control" mode, the second temperature sensing element (
13) to raise the temperature of the food to be cooked such as tempura oil to 160°~
While controlling the temperature to 200°C, the first temperature sensing element (11
) is set to detect an abnormal temperature rise in a pot of 240℃. (18) indicates that when the plug of the temperature probe having the second temperature sensing element (13) is inserted into the jack, the second temperature sensing element (13) is connected to the temperature control circuit (16).
otherwise, the first temperature sensing element (1
1) is a jack switch configured to be connected.

In addition, the state of each changeover switch (17) and jack switch (18) in FIG. 1 is the "temperature control" mode, and the state in which the temperature probe is inserted into the jack is shown.

FIG. 2 shows a circuit diagram of the temperature control circuit.

In the same figure, the circuit composed of the comparator (COMPI) is connected to the mode changeover switch (17) for "heating" and "heating".
Regardless of the temperature control mode, the pot remains active (12
) is activated when there is an abnormality such as dry cooking, and the normal comparator (CO
The output of MP1) is at "H" level and heating continues. When the first temperature detection element (13) detects an abnormal temperature of 240°C or higher, the comparator (COM
PI) outputs a “L” level signal, and the control circuit (15
) to stop the ON/OFF operation of the switching element (9).

The circuit consisting of the comparator (COMP2) is the original temperature control section, and as shown in the figure, the temperature probe (P) is inserted into the cooker body, and the jack switch (18) is set to the second
When connected to the second temperature sensing element (13) in the temperature probe, the e input changes depending on the resistance value of this second temperature sensing element (13) in the temperature probe, and
) until the output of the comparator (COMP2) reaches a predetermined setting value (for example, 200'C, which is the temperature for cooking tempura), the output of the comparator (COMP2) becomes "H" level, and the control circuit (15) switches the switching element ( 9) is turned on and off, a high frequency current is passed through the induction heating coil (8), and the pan (12) is heated by induction. Normally, in this state, tempura oil is placed in the pan (12).
The tempura is cooked while measuring its temperature with a temperature probe (P).

The frying oil in the pot (12) will rise and the temperature probe (P
) changes the resistance value of the second temperature sensing element (13) and when the e input of the comparator (COMP2) matches the ■ input, the output of this comparator (COMP21 becomes "L" level and the control Circuit (15) inhibits heating operations.

When the temperature of the tempura oil falls, the output of the comparator (COMP2+ becomes "H" level again and heating operation starts.

In this way, the tempura oil that is the object to be heated is maintained at the set value.

On the other hand, if the user inserts the plug of the temperature probe (Pl) into the jack and uses it in an incorrectly inserted state, the jack switch (18) will be connected to the contact on the opposite side from the state shown in Figure 2. , the comparator (COMP21) is connected to the first temperature sensing element (11) side.

Therefore, even in this case, the temperature of the pot (12) is detected through the top plate (S), so that the temperature of the pot (12) does not exceed the temperature set by the temperature setting means (VR). There is.

In such a cooker, "The temperature probe (P) is properly connected to the main unit in temperature control J mode, but the probe (P)
P) The tip may be heated while removed from the pot (12). In this case the second sensing element (13)
Although the detected temperature does not rise, the temperature of the actual object to be heated (tempura oil) in the pot (12) increases rapidly. However,
The first temperature sensing element (11) on the bottom surface of the top plate (S)
) is constantly compared with the comparator (COMPII), so the detected temperature is a predetermined abnormal temperature (240
℃), heating is stopped.

(g) Effects of the Invention As described above, the induction heating cooker of the present invention includes a control section that controls the generation of alternating magnetic flux from the heating coil, a first temperature detection means provided directly below the above-mentioned mounting plate, a second temperature detection means which is detachably provided on the cooker main body and whose temperature detection part can be inserted into the pot which is being heated, and these are the first and second temperature detection means. Since the control unit controls the heating of the pot based on the signal from the controller, even if the second temperature detection means cannot detect the temperature, the first temperature detection means can prevent abnormal heating, so that tempura cooking etc. can be prevented by the first temperature detection means. can prevent oil from igniting.

[Brief explanation of the drawing]

Fig. 1 is a circuit block diagram of the induction heating cooker of the present invention;
The figure is a circuit diagram of the temperature control circuit. .・(1)...Power switch, (5)...Bridge for rectification. (8)...Induction heating coil, (9)...Semiconductor switching element, (10)...Resonance capacitor, (11)...
)...first temperature sensing element, (I2)...pan, (1
3)...Second temperature detection element, (15)...Control circuit, (16)...Temperature control circuit, (17)...Mode switching switch, (18)...Jack switch ,
(S)...Top plate for pot device, (COM Pl
) (COMP2)...Comparator, (VR)...Temperature setting means.

Claims (1)

[Claims] 1) In an induction heating cooker that inductively heats a metal cooking pot placed directly above the placement plate by supplying an alternating magnetic field from an induction heating coil placed directly below the placement plate,
a control unit that controls generation of alternating magnetic flux from the heating coil; a first temperature detection means provided directly below the placement plate;
a second temperature detection means which is detachably provided on the cooker main body and whose temperature detection part can be inserted into the pot which is being heated, and these are the first and second temperature detection means. An induction heating cooker characterized in that the control section controls the heating of the pot based on a signal from the controller.