JPH0982467A - Electromagnetic cooker - Google Patents

Abstract

(57) Abstract: To provide an electromagnetic cooker capable of accurately and quickly controlling the temperature of a cooking pot to a set temperature. SOLUTION: A high frequency voltage generated by a pickup coil 21 due to a magnetic flux from a heating coil 8 interlinking is transmitted to a temperature sensing element 29 provided in a cooking pot via a transmitting coil 24 and a receiving coil 25, and the pickup coil is picked up. 21 is changed, and the heating coil 8 is changed based on the change in the current.
The temperature of the cooking pot is controlled properly and quickly by controlling the high frequency current supplied to the.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electromagnetic cooker for induction-heating a cooking pot provided in the vicinity of a heating coil by supplying a high-frequency current to the heating coil. Regarding the cooker.

[0002]

2. Description of the Related Art Induction cookers are safe without fire and have excellent thermal efficiency, and are rapidly becoming popular for household and business use. In such an electromagnetic cooker, a temperature control function for controlling the pan temperature at a constant level is added so that it is convenient for cooking fried foods.

Conventionally, the detection method of the pot temperature of the electromagnetic cooker is as follows.
A method of detecting the temperature of a pan placed on the top plate is used by a temperature sensitive element provided on the bottom surface of the top plate.

FIG. 8 is a circuit diagram of a conventional electromagnetic cooker. In the figure, the AC voltage from the AC power supply 1 is rectified by the full-wave rectifier 2 and further smoothed by the smoothing capacitor 3.
DC voltage is obtained. Two switching elements 4 and 5 connected in series are connected in parallel to the capacitor 3,
Diodes 6 and 7 are connected in parallel to the respective switching elements in opposite directions. The heating coil 8 is connected to the connection point of the two switching elements 4 and 5, and the resonance capacitors 9 and 10 are connected to the heating coil, thereby forming an inverter circuit. Reference numeral 11 is a control circuit for controlling the two switching elements 4 and 5, and an input setting section 12 for setting an input, an on-time variable section 13 for sending an on-time signal to the two switching elements 4 and 5, and an input current. It is composed of a current transformer 14 for detecting the temperature, and a temperature sensitive element temperature detecting section 16 for detecting the temperature of the temperature sensitive element 15 provided on the bottom surface of the top plate.

With this structure, the circuit operation of the electromagnetic cooker is as follows. By alternately turning on and off the two switching elements 4 and 5 with respect to the DC power source including the full-wave rectifier 2 and the smoothing capacitor 3, a high-frequency current is supplied to the heating coil 8 of the inverter circuit and the pot on the heating coil is opened. To heat. At this time, the on-time varying section 13 feeds back the input current detection signal from the current transformer 14 to determine the on-time of the switching elements 4 and 5 so that the input is set by the input setting section 12.
An on-time signal is sent to the switching elements 4 and 5. The input, that is, the thermal power changes when the on-time is changed, and the thermal power increases as the on-time increases. The temperature control is performed by detecting the temperature of the top plate by the temperature sensitive element 15, and the input setting unit 12 receives the detection signal and changes the setting input. That is, heating is performed with high input until the pot temperature reaches the set temperature, and after reaching the set temperature, the input is reduced and the input is controlled so as to maintain the set temperature.

[0006]

However, the conventional temperature control of the electromagnetic cooker has the following problems. That is, as shown in FIG. 9, the temperature control controls the input so that the temperature of the temperature sensitive element 15 at the bottom of the top plate 17 becomes a predetermined temperature. However, the top plate 17
Therefore, it cannot be said that the temperature of the pan 18 is necessarily controlled to the set temperature. Also, the top plate 17
Since there is a delay in heat transfer, it is not possible to perform input control that immediately follows changes in pot temperature. For example, as shown in FIG. 10, when cooking a deep-fried food, when the deep-fried food is thrown in, the temperature of the pan lowers, but it is delayed to detect this, so that the input cannot be immediately raised to return to the set temperature. In addition, when cooking deep-fried food continuously after cooking pot food, the top plate 17 keeps the temperature at the time of cooking pot food for a while. It may take some time.

The present invention has been made in view of the above,
An object of the invention is to provide an electromagnetic cooker capable of accurately and quickly controlling the temperature of a cooking pot to a set temperature.

[0008]

In order to achieve the above object, the present invention according to claim 1 induction-heats a cooking pot provided in the vicinity of a heating coil by supplying a high-frequency current to the heating coil. An electromagnetic cooker, which is provided in the vicinity of the heating coil, is provided in the cooking pot and a pickup coil that generates a high-frequency voltage by interlinking the magnetic flux generated from the heating coil, and controls the temperature of the cooking pot. Detect
Detecting means for generating an electric signal corresponding to the detected temperature, transmitting means for transmitting a high frequency voltage generated in the pickup coil to the detecting means, and the pickup coil due to a change in the electric signal via the transmitting means. And a control means for controlling a high-frequency current supplied to the heating coil by detecting a change in current flowing through the heating coil.

According to the first aspect of the present invention, the magnetic flux from the heating coil is linked to transmit the high frequency voltage generated from the pickup coil to the detecting means provided in the cooking pot, while the electric signal from the detecting means is transmitted. The temperature of the cooking pot is controlled properly and quickly by detecting the change in the current flowing through the pickup coil due to the change and controlling the high-frequency current supplied to the heating coil.

The present invention described in claim 2 is the same as the claim 1.
In the invention described above, the pick-up coil has a plurality of windings having different numbers of turns, and a switching means for switching the plurality of windings according to the magnitude of a high-frequency current supplied to the heating coil. To do.

According to the second aspect of the present invention, by switching the winding of the pickup coil according to the magnitude of the high frequency current, it is possible to perform accurate temperature control even when the input is lowered.

Further, the present invention according to claim 3 provides the invention according to claim 1.
In the invention described above, the pickup coil includes a plurality of coils having different interlinking areas of magnetic flux generated from the heating coil, and the plurality of coils are switched according to the magnitude of a high-frequency current supplied to the heating coil. The gist is to have a switching means.

According to the third aspect of the present invention, by switching the pickup coil to a coil having a different flux linkage area, it is possible to perform accurate temperature control even when the input is lowered.

Further, the present invention described in claim 4 is based on claim 1.
In the invention described above, the transmission means transmits the high frequency voltage generated in the pickup coil, and the high frequency voltage transmitted from the transmission coil by electromagnetically coupling to the transmission coil is received and transmitted to the detection means. In order to do so, the gist is to have a receiving coil provided in the cooking pot.

According to the fourth aspect of the present invention, the transmitting means is constituted by the transmitting coil and the receiving coil, so that the high-frequency voltage generated in the pickup coil is properly transmitted to the detecting means provided in the cooking pot. You can

Furthermore, the present invention according to claim 5 provides the invention according to claim 4.
In the invention described above, the gist of the invention is to have an alignment means formed to place the cooking pot at a predetermined position on the top plate so as to align the transmitting coil and the receiving coil.

According to the fifth aspect of the present invention, by placing the cooking pot at a predetermined position on the top plate, the transmitter coil and the receiver coil can be properly aligned.

The present invention according to claim 6 provides the invention according to claim 4.
Alternatively, in the invention described in 5, the gist is that the receiving coil is provided on a side portion of the cooking pot so as to be electromagnetically coupled to the transmitting coil.

According to the sixth aspect of the present invention, by providing the receiving coil on the side portion of the cooking pot, the electromagnetic coupling between the receiving coil and the transmitting coil can be appropriately performed.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a circuit diagram showing the structure of an electromagnetic cooker according to the first embodiment of the present invention, and FIG. 2 is a diagram showing a special cooking pot placed on the electromagnetic cooker shown in FIG. It is a figure which shows the structure in a case. In FIGS. 1 and 2, the same components as those in FIGS. 8 and 9 are designated by the same reference numerals, and the description thereof will be omitted.

In FIGS. 1 and 2, reference numeral 21 denotes a pickup coil provided below the top plate 17 and near the heating coil 8. The pickup coil 21
Consists of an autotransformer with one center tap,
The transmission coil 24 is connected to one end, and the intermediate tap and the other end are connected to a changeover switch 22 for switching on / off and the number of turns of the pickup coil 21. Also, 2
Reference numeral 0 is a pickup coil current detection unit that detects the current flowing through the pickup coil 21 by the current transformer 23, and 19 is a pot temperature control unit that changes the setting input and switches the pickup coil switch. Reference numeral 32 is a dedicated cooking pot to which the temperature sensitive element 29 is attached, and a smoothing circuit 28 composed of a rectifier 26 and a capacitor 27 connected to the temperature sensitive element 29, and the receiving coil 2
5 is built into the handle. Reference numerals 31 and 33 are ferrites for improving electromagnetic coupling between the transmitting coil and the receiving coil.

Under such a structure, the temperature control of the special cooking pot is performed as follows. The user, as shown in FIG.
The special cooking pot 32 is placed according to the line 34 drawn on the top plate 17. As a result, the position of the transmitting coil 24 inside the electromagnetic cooker and the position of the receiving coil 25 inside the pan are aligned. After this, enter the set temperature of the pan on the display panel,
Activate the temperature control function. When the temperature control function is activated, the pan temperature control unit 19 switches the changeover switch 22 from the position c to the position a, and the pickup coil 21 and the transmission coil 24.
Connect. After that, heating is performed with a predetermined high input. At this time, the high-frequency voltage generated in the pickup coil 21 by interlinking with a part of the magnetic flux generated from the heating coil 8 is supplied to the smoothing circuit 28 in the pan through electromagnetic coupling between the transmission coil 24 and the reception coil 25. . The smoothing circuit 28 converts this high frequency voltage into a direct current and supplies the direct current voltage to the temperature sensitive element 29. The temperature sensitive element 29 is, for example, a thermistor, and its resistance value decreases as the pot temperature rises, as shown in FIG.
As a result, when the pot temperature rises, the current flowing through the pickup coil 21 increases as shown in FIG. From this relationship, the pan temperature can be directly detected by detecting the pickup coil current.

After the pickup coil 21 current reaches the set pickup coil current value, the input is lowered to control the pot temperature to be constant. At this time, the high frequency voltage generated becomes small, and the current flowing through the pickup coil 21 becomes small as shown in FIG. For this reason, the dynamic range for detection becomes small and the pot temperature control becomes difficult. Therefore, at the time of low input, the switch 22 is switched to the position b to increase the number of turns of the pickup coil 21 so that the same high frequency voltage as that at the time of high input can be obtained.

The pot temperature can be directly detected by using the dedicated cooking pot with the temperature sensing element and the control circuit as described above, so that the pot temperature can be accurately maintained at the set temperature. Further, since there is no delay in detecting the pot temperature, input control can be performed immediately in response to changes in the pot temperature, and the pot temperature can be quickly returned to the set temperature.

FIG. 6 is a circuit diagram showing the structure of an electromagnetic cooker according to a second embodiment of the present invention, and FIG. 7 shows a dedicated cooking pot 32 placed on the electromagnetic cooker of FIG. It is a figure which shows the structure in a case. In FIGS. 6 and 7, the same components as those in FIGS. 1 and 2 are designated by the same reference numerals, and the description thereof will be omitted.

The electromagnetic cooker shown in FIGS. 6 and 7 is different from the electromagnetic cooker shown in FIGS. 1 and 2 only in the configuration of the pickup coil, and the other configurations are the same. That is, in FIGS. 1 and 2, an autotransformer having an intermediate tap is used as the pickup coil, but in FIGS. 6 and 7, a small pickup coil 3 having a different radius is used instead.
7 and a large pickup coil 38 are used so that the interlinkage areas with the magnetic flux generated from the heating coil 8 are different, and the two are switched between low input and high input. .

That is, when the special cooking pot 32 is heated with a predetermined high input, the switch 22 is switched from c to a, the magnetic flux is picked up by the small pickup coil 37, and the pickup coil current is the set pickup coil current. After reaching the value, the switch 22 is switched from a to b in order to lower the input and keep the pot temperature constant, and the large pickup coil 38 detects the magnetic flux due to the low input,
As a result, the same high frequency voltage as that at the time of high input is obtained. In the case of the same heating input, the voltage generated in the large pickup coil 38 is set to be higher than the voltage generated in the small pickup coil 37.

[0029]

As described above, according to the present invention as set forth in claim 1, the magnetic flux from the heating coil is interlinked and the high frequency voltage generated from the pickup coil is transmitted to the detecting means provided in the cooking pot. On the other hand, since the high-frequency current supplied to the heating coil is controlled by detecting the change in the current flowing in the pickup coil due to the change in the electric signal from the detecting means, the cooking pot temperature is directly detected, so the cooking pot is The temperature can be controlled accurately and quickly without transmission delay, and for example, fried food can be cooked well.

According to the second aspect of the present invention, since the winding of the pickup coil is switched according to the magnitude of the high frequency current, accurate temperature control is performed with high resolution even when the input is lowered. be able to.

Further, according to the present invention as set forth in claim 3, since the pickup coil is switched to a coil having a different flux linkage area, accurate temperature control can be performed with high resolution even when the input is lowered. it can.

According to the fourth aspect of the present invention, the transmission coil and the reception coil constitute the transmission means, so that the high frequency voltage generated in the pickup coil is accurately transmitted to the detection means provided in the cooking pot. can do.

Further, according to the present invention as set forth in claim 5, the transmitter coil and the receiver coil can be properly aligned by placing the cooking pot at a predetermined position on the top plate.

According to the sixth aspect of the present invention, by providing the receiving coil on the side of the cooking pot, the electromagnetic coupling between the receiving coil and the transmitting coil can be appropriately performed.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing a configuration of an electromagnetic cooker according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a configuration in which a dedicated cooking pot is placed on the electromagnetic cooker shown in FIG.

FIG. 3 is a diagram showing an alignment line for placing a dedicated cooking pot on the top plate of the electromagnetic cooker shown in FIG.

FIG. 4 is a graph showing temperature characteristics of a temperature sensitive element used in the electromagnetic cooker shown in FIG.

5 is a graph showing current characteristics of a pickup coil used in the electromagnetic cooker shown in FIG.

FIG. 6 is a circuit diagram showing a configuration of an electromagnetic cooker according to a second embodiment of the present invention.

FIG. 7 is a diagram showing a configuration when a dedicated cooking pot is placed on the electromagnetic cooker shown in FIG.

FIG. 8 is a circuit diagram showing a configuration of a conventional electromagnetic cooker.

9 is a diagram showing a configuration in which a cooking pot is placed on the conventional electromagnetic cooker of FIG.

FIG. 10 is a graph showing characteristics of the conventional electromagnetic cooker shown in FIG.

[Explanation of symbols]

 4, 5 Switching element 8 Heating coil 12 Input setting section 13 On-time variable section 19 Pot temperature control section 20 Pickup coil current detection section 21 Pickup coil 22 Switch 23 Current transformer 24 Transmission coil 25 Reception coil 29 Thermosensitive element 32 Cooking pot

Claims (6)

[Claims] 1. An electromagnetic cooker for inductively heating a cooking pot provided in the vicinity of a heating coil by supplying a high frequency current to the heating coil, the induction cooker being provided in the vicinity of the heating coil. A pickup coil for generating a high-frequency voltage by interlinking the generated magnetic flux; a detection unit provided in the cooking pot for detecting the temperature of the cooking pot and generating an electric signal corresponding to the detected temperature; Transmission means for transmitting the high-frequency voltage generated in the pickup coil to the detection means, and high-frequency supplied to the heating coil by detecting the change in the current flowing in the pickup coil due to the change in the electric signal via the transmission means. An electromagnetic cooker comprising: a control unit that controls an electric current. 2. The pickup coil has a plurality of windings with different numbers of turns, and has a switching means for switching the plurality of windings according to the magnitude of a high-frequency current supplied to the heating coil. The electromagnetic cooker according to claim 1. 3. The pickup coil has a plurality of coils having different interlinking areas of magnetic flux generated from the heating coil, and the plurality of coils are arranged according to the magnitude of a high frequency current supplied to the heating coil. The electromagnetic cooker according to claim 1, further comprising switching means for switching. 4. The transmission means transmits a high frequency voltage generated in the pickup coil, and a high frequency voltage electromagnetically coupled to the transmission coil to receive the high frequency voltage transmitted from the transmission coil. The electromagnetic cooker according to claim 1, further comprising a receiving coil provided in the cooking pot for transmission. 5. The positioning means is formed so as to place the cooking pot at a predetermined position on the top plate so as to position the transmitting coil and the receiving coil. Electromagnetic cooker. 6. The electromagnetic cooker according to claim 4, wherein the receiving coil is provided at a side portion of the cooking pot so as to be electromagnetically coupled to the transmitting coil.