JP2005166567A - Induction heating cooker - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a safe induction heating cooker in which the bottom side temperature of the pot does not become a temperature extremely higher than the temperature necessary for cooking. <P>SOLUTION: The induction heating cooker comprises one lot or more heater coil 1, a top plate 3 for putting a heating object 4, a temperature detection means 2 for detecting the temperature of the heating object 4, and a control circuit 5 for controlling the power of the heater coil 1 by the signal from the temperature detection means 2 with the maximum input power for one lot of 2 kw or more. The control circuit 5 performs a control to reduce the input power to 1.0 kw or less when the rising speed of the detected temperature of the temperature detection means 2 during heating is at a prescribed temperature rising speed between 0.2 to 1°C/sec and the detected temperature is at a prescribed temperature or more between 50 to 150°C, and makes the bottom side temperature of the pot 4 not to reach oil ignition temperature. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to power control of an induction heating cooker that heats a load (a heated object) such as a pan by flowing a high-frequency current through a heating coil.

  An induction heating cooker allows high-frequency current to flow through a heating coil to generate an eddy current in a metallic pan placed on the top plate of the heating coil, and the pot itself self-heats due to its Joule heat, making the pan efficient. It heats well.

  In a conventional induction heating cooker, particularly for home use, a temperature detecting means such as a thermistor is applied under the top plate on which a load such as a pan is placed, and the temperature of the load is indirectly measured by heat conduction of the top plate. When the temperature is detected (for example, Patent Document 1) and this temperature reaches a predetermined temperature or more, the power is reduced (for example, Patent Document 2) or the control is performed to stop.

  One of the purposes is to maintain the temperature of the oil in the pan at a constant temperature between about 150 ° C. and 200 ° C., which is a suitable temperature for the fried food, in an induction heating cooker having a fried food heating mode. .

  Another purpose is to stop the power or control the power so that the food or oil inside the heated object such as a pan does not rise above the temperature required for normal cooking in the normal heating mode. This is to prevent dangers such as food ignition. At the same time, it has the purpose of improving the life of the pan by preventing deformation due to the abnormally high temperature of the pan and peeling of the fluorine coat inside the pan.

  The conventional control will be described with reference to FIG. FIG. 3 is a graph showing changes in the bottom temperature of the pan, the temperature of the temperature detecting means, and the time of input power when heating of an almost empty pan is started with the maximum heating power (2 kW) of the conventional induction heating cooker.

  In FIG. 3, when heating is started, the maximum heating power (2 kW) is input, and the bottom temperature of the pan starts to rise rapidly because of the almost empty pan. The bottom temperature of the pan is detected by temperature detection means such as a thermistor, but the temperature detection means is indirectly detected via a top plate such as glass, and therefore rises considerably later than the bottom temperature of the pot.

  In a control circuit including a microcomputer or the like, the temperature of the temperature detecting means is determined, and when the time T1 becomes 250 ° C. or higher, the input power is set to 0 W, and when the temperature is lower than 250 ° C., the input power is set to 2 kW again. And control is performed so that the temperature detecting means temperature is stabilized at about 250 ° C.

  Note that the control temperature 250 ° C. here is set to have a margin because it requires a high temperature of about 220 ° C. for cooking steaks and the like.

Japanese Patent No. 2,964,566

Japanese Patent Laid-Open No. 5-62772

  In the above conventional operation, when the pan is heated with a small load (foodstuff) as an object to be heated or when it is empty, the bottom surface temperature of the pan when the temperature of the temperature detecting means reaches the control temperature of 250 ° C. May be over 370 ° C., which is the ignition temperature of oil, and at this time, it may be in a dangerous state in which the oil and food materials ignite.

  Even if it does not ignite, the pan is heated to a temperature higher than the required temperature each time it is heated, so the pan life is significantly shortened, such as deformation due to abnormally high temperature of the pan and peeling of the fluorine coating inside the pan. There was a problem of lowering.

  As a method for solving such a problem, as shown in Patent Document 2, when the temperature detection means detects the temperature increase rate, and the detected temperature is equal to or higher than the predetermined temperature increase rate and the detected temperature is equal to or higher than the predetermined temperature. The control for reducing the input power to a predetermined power or less was performed, but the specific control method is a predetermined temperature between 0.2 ° C. and 1 ° C./sec. The control was such that the input power was reduced to 102 kW when the rising speed was exceeded and the detected temperature was 120 ° C. or more.

  However, in this case, the maximum width of the rising temperature in FIG. 3 can be reduced, but it is difficult to reliably keep the bottom surface temperature of the pan below 370 ° C., which reliably prevents the ignition of oil. And deterioration of the pan could not be prevented.

  This invention solves said subject and provides the safe induction heating cooking appliance with which the bottom face temperature of a pan does not become a remarkably high temperature from the temperature required for cooking.

  In order to solve the above-described problems, the present invention includes one or more heating coils, a top plate on which an object to be heated is placed, and temperature detection means for detecting the temperature of the object to be heated via the top plate. In the induction heating cooker having a maximum input power of 2 kW or more, the rate of increase in the temperature detected by the temperature detection means during heating is not less than a predetermined temperature increase rate between 0.2 ° C. and 1 ° C./second, and When the detected temperature is equal to or higher than a predetermined temperature between 50 ° C. and 150 ° C., control is performed to reduce the input power to 1.0 kW or lower.

  According to the present invention, even when the load (foodstuff) that is the object to be heated is small or the pan is heated in an empty state, the temperature at the bottom of the pan can be made lower than the ignition temperature of the oil. And the risk of fire of ingredients.

  In addition, since the pan is not heated to a temperature higher than the required temperature every time it is heated, the pan can be prevented from being deformed due to abnormally high temperatures, and the fluorine coating inside the pan can be peeled off. Can be improved.

  An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram illustrating the structure of a heating unit according to an embodiment of the present invention. FIG. 2 is a diagram illustrating the temperature of the bottom of the pan, the temperature of the temperature detection means, and the time of input power when the pan is started to be heated by the induction heating cooker of the present invention. It is a figure which shows the change of.

  In these figures, 1 is a heating coil, 2 is a temperature detecting means constituted by a thermistor, 3 is a top plate made of heat-resistant tempered glass or ceramic, 4 is a pan that is an object to be heated, 5 includes a microcomputer, etc. It is a control circuit.

  The pan 4 is placed on the top plate 3, and the heating coil 1 is installed on the lower surface of the top plate 3 facing the pan 4. One or more heating coils 1 are installed in a container (not shown). And the temperature detection means 2 is closely_contact | adhered to the lower surface of the top plate 3 from the center part of the heating coil 1, and detects the temperature of the pan 4 indirectly. A heating coil 1 and a temperature detecting means 2 are connected to the control circuit 5.

  The control of this embodiment will be described with reference to FIG. FIG. 2 shows the time variation of the bottom temperature of the pan 4, the temperature of the temperature detecting means, and the input power when the heating of the almost empty pan is started at the maximum heating power (2 kW).

  In these figures, when heating is first started by the heating coil 1, the maximum heating power (2 kW) is input, and the bottom temperature of the pan 4 starts to rise rapidly. The temperature detection means 2 such as a thermistor detects the bottom temperature of the pan 4, but the temperature detection means 2 is indirectly detected via a top plate 3 such as glass, and therefore rises considerably later than the bottom temperature of the pot 4. To do.

  In the control circuit 5 including a microcomputer or the like, the signal (temperature) from the temperature detecting means 2 is determined, and the detected temperature is equal to or higher than a predetermined temperature between 50 ° C. and 120 ° C. (100 ° C. in the embodiment) at time T2. And the temperature rise rate at this time is determined to be not less than a predetermined temperature rise rate between 0.2 ° C. and 1 ° C./sec (0.5 ° C./sec in the embodiment), and the input power is 1 It is reduced to a predetermined heating power of 1.0 kW or less (1.0 kW in the embodiment). As a result, the rise in the bottom surface temperature of the pan 4 becomes gradual, and the temperature difference from the temperature detecting means 2 becomes small.

  After that, when the temperature of the temperature detecting means 2 reaches 250 ° C. or higher at the time T3 when the bottom surface temperature of the pan 4 is lower than the oil ignition temperature (about 370 ° C.), the input power is set to 0 W, and thereafter lower than 250 ° C. Then, the control is performed again so that the input power is 2 kW, and the temperature of the temperature detecting means 2 is controlled so as to be stabilized at about 250 ° C.

  FIG. 2 shows the control when the almost empty pan 4 is heated. For example, even when a small amount of oil is added, the danger that the oil will ignite can be prevented because it is lower than the ignition temperature.

  Moreover, when the load (foodstuff) of the pan 4 is heavy, the rise in the bottom surface temperature of the pan 4 becomes slow, so that the temperature rise rate of the temperature detecting means 2 is a predetermined value between 0.2 ° C. and 1 ° C./second. The temperature rise rate is less than 0.5 ° C./second in the embodiment, the maximum heating power (2 kW) is input until the temperature detecting means 2 reaches 250 ° C., and there is no problem that the cooking time is delayed.

  As described above, when the range of the rising speed of the temperature detection means 2 is 0.2 ° C. to 1 ° C./second, the detection temperature range is 120 ° C., and the input power range is 1.0 kW or less, there are various As a result of conducting a measurement experiment with no pot, it was possible to reliably suppress the ignition of the oil without deteriorating the usability in actual cooking, and to suppress the deterioration of the pan.

  In FIG. 1, the ON / OFF control is described as an example. However, the present invention is an invention regarding a control method at a temperature extremely lower than the control temperature, and what kind of control is used for a control method near the control temperature. A method may be used.

  As described above, according to the present invention, the temperature of the bottom surface of the pan 4 when the load (foodstuff) of the pan 4 is small or when heating is started in an empty state is set lower than the ignition temperature of the oil. Therefore, it is possible to prevent the danger of ignition of oil and food materials.

  Moreover, since the pan 4 is not heated to a temperature higher than the necessary temperature every time it is heated, the pan 4 can be prevented from being deformed due to an abnormally high temperature, the fluorine coat peeling of the pan 4, etc. Can be significantly improved.

It is structure explanatory drawing which shows the heating part of one Example of this invention. It is a figure which shows the time change of the bottom face temperature of a pan when the heating of the pan of this invention is started, the temperature of a temperature detection means, and input electric power. It is a figure which shows the time change of the bottom face temperature of a pan when the heating of the pan of a prior art example is started, the temperature of a temperature detection means, and input electric power.

Explanation of symbols

1 Heating coil 2 Temperature detection means 4 Pan 5 Control circuit

Claims (1)

One or more heating coils (1), a top plate (3) on which the object to be heated (4) is placed, and temperature detection means for detecting the temperature of the object to be heated (4) via the top plate (3) (2) and a control circuit (5) for controlling the power of the heating coil (1) by a signal from the temperature detection means (2), and an induction heating cooker having a maximum input power per mouth of 2 kW or more The temperature detection means (2) during the heating has a detection temperature increase rate of not less than a predetermined temperature increase rate between 0.2 ° C. and 1 ° C./second and a detection temperature of 50 ° C. to 150 ° C. An induction heating cooker, wherein the control circuit (5) performs control to reduce the input power to 1.0 kW or less when the temperature is above a predetermined temperature.

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